ORIGINAL ARTICLE
Chronic Low Back Pain Perception and Coping With Pain in the Presence of Psychiatric Comorbidity Antonella Ciaramella, MD* and Paolo Poli, MD† Abstract: This retrospective study investigated the influence of psychiatric comorbidity on pain perception and coping with pain in tertiary pain clinic patients, 427 treated for chronic low back pain (CLBP) and 629 for other forms of chronic pain (CG). No differences in psychosomatic dimensions were found between the two groups, but Italian Pain Questionnaire dimensions and intensity scores (t = 7.35; p < 0.0001) were higher in CLBP than in CG subjects. According to the Mini-International Neuropsychiatric Interview, CLBP patients also had a higher prevalence of lifetime major depressive episodes (χ2 = 4.96; p < 0.05), dysthymic disorder (χ2 = 4.64; p < 0.05), suicide risk (χ2 = 10.43; p < 0.01), and agoraphobia (χ2 = 6.31; p < 0.05) than CG patients did. The Multidimensional Pain Inventory showed a close association between CLBP and both agoraphobia (χ2 = 3.74; p < 0.05) and dysfunctional coping style (χ2 = 8.25; p < 0.01), which increased disability. Both agoraphobia and lifetime depression were associated with an overall increase in dimensions and pain intensity in CLBP, but not in CG. Key Words: CLBP, psychiatric disorders, sex, coping, pain perception, agoraphobia, DCPR criteria, tertiary care (J Nerv Ment Dis 2015;203: 632–640)
C
hronic low back pain (CLBP) is a condition that is both caused and maintained by the interaction and mutual influence of several biological, psychological and social factors (Dersh et al., 2001; Waddell, 2004). In CLBP, there is a high degree of comorbidity, and reports of additional somatic and psychological symptoms and complaints are common (Carnes et al., 2007; Hagen et al., 2006; Von Korff et al., 2005). The prevalence of comorbid psychiatric disorders is often assessed and considered, but in most cases, questionnaires, rather than diagnostic interviews, are the assessment tool of choice (e.g., Currie and Wang, 2004; Manchikanti et al., 2002; Mok and Lee, 2008). Studies that have been conducted via diagnostic interviews show a consistently high prevalence of psychiatric comorbidities in CLBP, ranging from 41% to 99% (Atkinson et al., 1991; Dersh et al., 2006; Kinney et al., 1993; Polatin et al., 1993; Reich et al., 1983). The most common comorbid conditions are somatoform disorders, affective disorders, and substance abuse disorders, with major depression being the most common single diagnosis (Kinney et al., 1993; Polatin et al., 1993). There is also a significantly greater prevalence of psychiatric disorders in those reporting CLBP compared with those without CLBP in the general population, as seen across 17 countries in global mental health surveys (Demyttenaere et al., 2007). Furthermore, psychosocial risk factors—so-called pain-prone factors—are partially responsible for lengthening the duration of pain syndromes, which can also be exacerbated by associations with life events and lack of coping strategies. A lifetime history of major depression or a major anxiety disorder may represent potential psychosocial *Aplysia onlus, GIFT Institute of Integrative Medicine; and †Pain Therapy Unit, Azienda Ospedaliero-Universitaria Pisana, Pisa, Italy. Send reprint requests to Antonella Ciaramella, MD, Aplysia onlus, GIFT Institute of Integrative Medicine, p.za Cairoli, 12, 56127 Pisa, Italy. E-mail: [email protected]. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0022-3018/15/20308–0632 DOI: 10.1097/NMD.0000000000000340
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risk factors for transition to chronic pain in men with first-onset low back pain (LBP). These patients may benefit from referral for more intensive rehabilitation, and screening for lifetime depressive or anxiety disorders to identify individuals at higher risk is therefore advisable (Shaw et al., 2010). Indeed, somatic assessment has revealed that the fewer the structural and neurological deficits in CLBP, the more psychiatric symptoms are present (Mayr et al., 2003). This may help explain why 85% of CLBP disorders have no identifiable cause, being classed as “nonspecific CLBP” and thereby leaving a large diagnostic and management vacuum (O'Sullivan, 2005). Vice versa, the number of pain complaints has been found to increase the likelihood of psychopathology (Katon and Sullivan, 1990), and more widespread pain has been associated with disability (Kamaleri et al., 2008). Concurrent psychopathology is likely to worsen prognosis (Linton, 2000) and outcome in CLBP (Dersh et al., 2007) and increase the burden on the health care services (Engel et al., 1996). Clinical guidelines therefore stress the importance of screening for concurrent psychopathology in these patients (Airaksinen et al., 2006). Although a strong association between CLBP and anxiety and depression has been found (Sagheer et al., 2013), we are still lacking knowledge regarding their impact on the affective dimension of pain, and few studies have investigated the influence of psychiatric comorbidities on pain management in a tertiary care setting. According to Chris et al. (2007), rather than changing the intensity of pain, the focus of a tertiary care multidisciplinary pain management program should be to reduce the intrusiveness of the emotional component of pain. It is therefore vital to evaluate the affective component of pain in such patients. The primary objective of this study was to reveal any differences in sociodemographic characteristics, perception of pain, and/or psychosomatic dimensions between CLBP and a control group comprising patients with other forms of chronic pain (CG), all treated in a tertiary pain clinic. We also investigated the prevalence of psychiatric comorbidities, according to the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) and International Classification of Diseases (ICD-10), in both groups and evaluated their impact on perception and coping with pain.
METHODS Participants and Study Design This retrospective study looked at 1056 subjects treated for chronic pain (427 CLBP and 629 GP) at a tertiary pain clinic (at the Azienda Ospedaliero-Universitaria di Pisana, Italy). After referral to the unit, subjects were evaluated by both an anesthetist, expert in pain therapy (P.P.), and a psychiatrist (A.C.), for pain threshold and perception assessment. All patients investigated (CLBP and CG) had already been unsuccessfully given surgical, anesthetic, and analgesic drug treatment, and no variations in spinal radiological, ultrasound, nuclear magnetic resonance, or inflammatory blood parameters in their medical records were able to explain the persistence of pain. All patients were evaluated using a multidimensional pain questionnaire (Italian Pain Questionnaire [IPQ]; see Measures section) to assess the affective dimensions of their pain. Some of them agreed to be assessed for
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The Journal of Nervous and Mental Disease • Volume 203, Number 8, August 2015
Psychiatric Disorders in CLBP
psychiatric disorders using a semistructured interview, the MiniInternational Neuropsychiatric Interview (MINI) Plus (Ciaramella et al., 2004), administered by a psychiatrist with at least 1 year's training in use of the tool. After psychiatric assessment, patients were asked to self-assess pain coping through the Multidimensional Pain Inventory (MPI) (see below), but some refused to continue the (rather lengthy) evaluation procedure at this point. Therefore, the data on psychiatric disorders and coping with pain are not available for all patients (see Results). A classification of CLBP includes different clinical forms (O'Sullivan, 2005); we defined CLBP as back pain persisting for longer than 7 to 12 weeks (Andersson, 1999). All subjects had a history of at least one treatment failure, with 55% of CLBP patients reporting persistent pain after laminectomy and 11% after spinal stabilization surgery (failed back surgery syndrome). The CG comprised subjects with various forms of chronic pain (Table 1) as a sample of the general population referred to the multidisciplinary pain center. All principles of the Helsinki declaration were adhered to, and all subjects provided informed written consent before the evaluation.
answers and covers 23 axis 1 disorders. In the multiaxial system of DSM-IV, axis I disorders include all major mental disorders, as well as developmental and learning disorders. The MINI interview usually takes 15 to 20 minutes and has high reliability and validity (Sheehan et al., 1998). We used the Italian version of MINI Plus (Ciaramella et al., 2004), which features questions on rule-outs (e.g., depressive reaction due to grief ), disorder subtyping (e.g., somatoform pain disorder [SPD] related to psychological factors or somatic condition), and chronology (e.g., when was the first time you experienced a panic attack) and includes modules for somatization disorders (e.g., hypochondriasis and SPD). MINI Plus further uses different timeframes for various disorders: current, past, or lifetime, that is, “the preceding 2 weeks (major depression), the past month (panic disorder, social phobia, obsessive compulsive disorder, PTSD), the past 12 months (alcohol dependency/ abuse), or ongoing at the time of interview with no further time reference (mania, agoraphobia, generalized anxiety disorder, psychotic disorders, somatisation disorders, anorexia, bulimia).” In this way, MINI differs from most other diagnostic interviews that usually ask for symptoms within the past 12 months.
Measures
Self-Assessment
Clinical Assessment
The somatosensory amplification scale The Somatosensory Amplification Scale (SSAS) is a 10-item self-report questionnaire that measures hypervigilance to body sensations, the tendency to select weak and infrequent sensations, and a disposition to react to somatic sensations with effects on cognitions that intensify them and make them more alarming and disturbing. Patients were asked to indicate how much each symptom had bothered them in the preceding 24 hours using a 5-point scale, with responses ranging from “not at all” to “extremely.” A higher total score indicates greater symptom amplification (Barsky et al., 1990).
Cold pressure test The nondominant limb was immersed in icy water (−0, 5–2°C) for a maximum of 240 seconds after temperature standardization, via limb immersion, in water at body temperature (37°C ± 0.5°C) for 240 seconds. We identified the pain threshold as the time from the immersion of the limb in the icy water until the first pain sensation. We defined pain tolerance as the time from the immersion of the limb in the icy water until the limb retracted intolerable pain (Wolff, 1984). The MINI was applied as the structured diagnostic interview (Sheehan et al., 1998) for DSM-IV (American Psychiatric Association, 1994) and ICD-10 (World Health Organization, 1993) assessing psychiatric disorders. It is based on “yes” and “no”
Italian pain questionnaire The IPQ (in the form of Questionario Italiano Del Dolore; De Benedittis et al., 1988) derives from the McGill Pain Questionnaire; it uses the factorial structure proposed by Melzack and Torgerson
TABLE 1. Clinical Factors in CLBP Compared With CG Subjects Evaluated in a Tertiary Pain Clinic CLBP (n = 427) n (%) Onset of pain, mos Pain syndromes FBSS LBP PP IP PHN CRPS Arthrosis Headache Facial pain Fibromyalgia Cancer Others Pain comorbidity Current treatment of pain Current treatment of psychiatric disorders
Mean (SD)
CG (n = 629) n (%)
101.76 (106.43)
Mean (SD)
t/χ2
102.42 (132.24)
0.06
283 (66.27) 144 (33.72)
324 (76.22) 328 (77.16) 178 (38.84)
39 (6.20) 24 (3.80) 39 (6.17) 25 (4.03) 7 (1.18) 145 (23.27) 46 (7.36) 65 (8.78) 82 (13.77) 157 (24.94) 465 (74.43) 490 (77.95) 232 (36.70)
0.11 0.88 0.11
t is value of t-test analysis for unpaired data. χ2 is chi value of square analysis. FBSS indicates failed back surgery syndrome; PP, phantom pain; IP, ischemic pain; PHN, postherpetic neuralgia; CRPS, complex regional pain syndrome.
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(1971) made up of three factors or classes (Sensorial, Affective, and Evaluative). The visual analog scale (VAS) consists of a line, usually 10 cm long, whose ends are labeled as the extremes of pain (no pain to pain as bad as it could be). Patients are asked to indicate which point along the line best represents their pain intensity. The distance from the no pain end to the mark made by the patients is the intensity score (Jensen and Karoly, 1992).
The Toronto alexithymia scale The Toronto Alexithymia Scale (TAS) is a 20-item instrument that is one of the most commonly used measures of alexithymia. Alexithymia refers to people who have trouble identifying and describing emotions and who tend to minimize emotional experience and focus attention externally (Bagby et al., 1994).
Statistical Analysis Multidimensional pain inventory The MPI was developed to fill a widely recognized void in the assessment of clinical pain. Three parts of the inventory, composed of 12 scales, examine the impact of pain on the patients' lives, the responses of others to the patients' communications of pain, and the extent to which patients participate in common daily activities. We used the Italian version of MPI (Ferrari et al., 2000). The MPI Program software developed by Rudy (2004) allows the dimensions to be clustered into categories of related maladaptive pain coping according to the distinct profiles identified by Turk and Rudy, 1988. In this study, we used three principal categories: Dysfunctional (DYS), Interpersonally Distressed (ID), and Adaptive Copers (AC). DYS patients score high on pain severity, life interference, and emotional distress but low on perceived control and activity. ID patients additionally report low level of social support. In contrast, AC patients show low level of pain, interference, and distress but high levels of life control and activity (Rusu and Hasenbring, 2008). The irritability depression anxiety scale The Irritability Depression Anxiety Scale (IDAS) is a 14-item self-administered assessment that includes four items to assess irritability, five items to measure anxiety, and five items to evaluate depression. The IDAS is a validated instrument capable of distinguishing between depressive and anxiety disorders. The IDAS investigates depression not only with symptoms of negative mood but also using the absence of positive mood (Snaith et al., 1978).
The data were analyzed using StatView 5.0 software (SAS Institute Inc; Landau and Rabe-Hesketh, 1999). After the application of Kolmogorov-Smirnov test, which gives details about the Gaussian distribution of the data, we investigated the differences between CLBP and CG using t-test analysis. Differences in the frequency of psychiatric disorders among various diagnostic pain groups were assessed with chi-square analysis using Fisher exact test for a small sample. Logistic regression analysis was performed considering only the psychiatric disorder that showed statistical differences between groups as a dependent variable. This last analysis was performed to evaluate differences in pain perception variables, tolerance of painful stimulus, and somatosensory amplification between the two groups, distinguished on the basis of presence of psychiatric disorders according to axis I categories of DSM-IV. Chi-square analysis was performed to measure differences in sociodemographic variables and psychiatric disorders between groups, distinguished on the basis of maladaptive pain related coping. Data are presented as mean ± SD, with a level of significance at p < 0.05.
RESULTS Differences in Sociodemographic and Clinical Factors Between CLBP and CG Subjects A total of 427 CLBP subjects were compared with 629 subjects with other forms of chronic pain as control (CG). Table 1 shows the percentage of pain syndromes included in the CG.
TABLE 2. Sociodemographic Factors in CLBP Compared With CG Subjects Evaluated in a Tertiary Pain Clinic CLBP (n = 427) n (%) Age Education, yrs Sex Males Females Marital status Married Divorced Single Widower Income High Medium Low
Mean (SD)
CG (n = 629) n (%)
60.97 (13.75) 8.60 (4.53)
Mean (SD)
t/χ2
52.66 (17.08) 11.37 (5.13)
8.31**** 6.06****
167 (39.32) 260 (60.67)
201 (31.95) 428 (68.04)
4.82*
278 (65.10) 42 (9.83) 42 (9.83) 65 (15.22)
371 (58.98) 44 (6.99) 151 (24.00) 63 (10.01)
11.56**
16 (3.74) 289 (67.68) 122 (28.57)
13 (20.06) 535 (85.05) 81 (12.87)
13.08***
t is value of t-test analysis for unpaired data. χ is chi value of square analysis. *p < 0.05. **p < 0.01. ***p < 0.001. ****p < 0.0001. 2
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The Journal of Nervous and Mental Disease • Volume 203, Number 8, August 2015
Differences Between CLBP and CG Subjects in the Perception of Pain and Psychosomatic Dimensions
TABLE 3. Perception of Spontaneous Pain, Psychosomatic Factors, Threshold, and Tolerance of Pain Induced by Cold Water Stimulus in CLBP Compared With CG Subjects Evaluated in a Tertiary Pain Clinic
Sensorial dimension Affective dimension Evaluative dimension VAS Cold pain threshold, sec Cold pain tolerance, sec Irritability (IDAS) Depression (IDAS) Anxiety (IDAS) SSAS total scoring Toronto Alexitymia Scale 20 total scoring
CLBP (n = 427)
CG (n = 629)
t
0.40 (0.16) 0.39 (0.22) 0.46 (0.28) 8.04 (2.03) 22.62 (25.50) 63.61 (38.82) 3.53 (2.82) 6.56 (2.95) 6.23 (3.16) 14.48 (6.34) 50.89 (13.03)
0.34 (0.15) 0.36 (0.22) 0.37 (0.25) 7.35 (2.13) 18.93 (20.41) 56.30 (39.50) 3.69 (2.62) 6.92 (3.13) 5.82 (3.32) 15.97 (6.68) 49.22 (14.27)
5.95*** 2.15* 5.95*** 5.21*** 1.73 2.07* 0.42 0.82 0.88 2.91** 1.02
Psychiatric Disorders in CLBP
Pain perception was investigated using two different approaches. In the first, clinical pain was investigated using a multidimensional questionnaire (IPQ) in which spontaneous (or clinical) pain is evaluated in the sensorial, affective, and evaluative dimensions, and its intensity, on a VAS. As part of the psychophysical analysis to assess pain threshold and tolerance, we also evaluated the perception of pain through the application of cold water as a painful stimulus (cold pressure test). Sensorial and evaluative, more so than affective, dimensions were higher in CLBP than in CG subjects. CLBP subjects reported more severe pain than CG subjects did (Table 3). However, across all subjects investigated (n = 1056), the value of some dimensions were strongly dependent on age. In fact, using age as the dependent variable in multiple regression analysis, we found a strong positive correlation with evaluative dimensions (t = 3.66, p = 0.0003) and a smaller positive relationship with sensorial dimensions of pain (t = 2.21, p = 0.02). Pain dimensions and intensity were both lower in male subjects (more markedly so in the CLBP group). Bonferroni's correction showed a statistically significant reduction in scores for sensorial (p = 0.007), affective (p = 0.01), and evaluative (p = 0.04) dimensions and intensity of pain (VAS) (p = 0.01) in men with respect to women. The higher values found for all dimensions and pain intensity in CLBP subjects is not sufficiently explained by demographic data, as these factors have different impacts on the perception of pain. The higher intensity of pain in the CLBP group was confirmed using the MPI (Table 4), but differences in the negative perception of spontaneous pain were not confirmed through induction of a cold painful stimulus. Indeed, CLBP subjects showed a higher tolerance (better endurance) to the cold pressure test than the CG did (Table 3). In accordance with the Diagnostic Criteria for Psychosomatic Research (DCPR; Porcelli and Rafanelli, 2010), we investigated
t is value of t-test analysis for unpaired data. Data are presented as mean (SD). *p < 0.05. **p < 0.01. ***p < 0.0001.
As shown in Table 2, the CLBP group is older, with a lower education level, and features a higher prevalence of men than the CG does. More CLBP patients were married and/or on a low income. No differences were found between groups in terms of time since pain onset, number of other chronic pain comorbidities, current pain treatment, or psychiatric comorbidity (Table 1).
TABLE 4. Pain Coping and Coping Style Disability in CLBP Compared With CG Subjects Evaluated in a Tertiary Pain Clinic CLBP (n = 285) Mean (SD) MPI dimensions Pain Severity Interference Life Control Affective Distress Social Support Punishing Responses Solicitous Responses Distracting Responses Household chores Outdoor work Activity away from home Social activities General activity level MPI coping style DYS ID AC
CG (n = 248)
n
%
4.58 (1.25) 4.28 (1.40) 3.52 (1.41) 3.32 (1.22) 4.16 (1.65) 2.53 (2.10) 3.05 (1.83) 3.02 (2.82) 3.12 (1.79) 2.01 (1.94) 1.73 (1.52) 2.18 (2.40) 2.18 (1.17)
Mean (SD)
n
4.01 (1.40) 3.55 (1.48) 3.39 (1.43) 3.20 (1.27) 4.41 (1.64) 1.41 (1.41) 3.50 (1.48) 2.60 (1.55) 3.61 (1.94) 1.69 (1.75) 2.23 (1.41) 2.41 (1.44) 2.51 (1.18) 82 108 95
28.77 37.89 33.33
t/χ2
%
4.60*** 5.80*** 0.28 1.05 1.77 7.06*** 3.06* 2.87* 2.81* 1.78 3.57** 1.17 3.02* 45 108 95
18.14 43.54 38.30
8.25*
t is value of t-test analysis for unpaired data. χ is chi value of square analysis. *p < 0.01. **p < 0.001. ***p < 0.0001. 2
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depression, anxiety, and irritability using the IDAS; alexithymia using the TAS; and somatosensory amplification the SSAS (Fava and Sonino, 2000). Of these, only the global SSAS showed any intergroup difference, being lower in the CLBP group than in the CG (Table 3).
Differences Between CLBP and CG Subjects in Psychiatric Disorder Comorbidity Only 879 subjects (416 CLBP and 463 CG) were investigated for psychiatric disorders with a semistructured interview, as, globally, there were 176 (n = 11 CLBP and n = 165 CG) dropouts at the psychiatric assessment stage. The CG displayed a higher dropout rate than the CLBP group did (χ2 = 102.47; p < 0.0001), but no differences were found between dropouts and continuers in age, sex, marital status, income, IPQ dimensions, or VAS pain scores. The number and percentages of psychiatric comorbidities are shown in Table 5. Lifetime prevalences of major depressive episodes, manic and hypomanic episodes, panic disorder, suicide risk (SR), generalized anxiety, and somatoform disorders were investigated using the MINI plus. This showed that CLBP patients had a greater prevalence of lifetime major depressive episodes (MDEL) and dysthymic disorder (DD), as well as higher scores for SR and agoraphobia, with and without panic (AWP and AWOP, respectively), than CG did (Table 5).
TABLE 5. Psychiatric Disorders Assessed According to DSM-IV in CLBP Compared With CG Subjects CLBP (n = 416) n Major depressive episode current 136 Major depressive episode lifetime 205 Dysthymic disorder 38 Hypomanic episode 29 Manic episode 4 Suicidal risk 52 Panic disorder 66 Agoraphobia without panic disorder 41 Agoraphobia with panic disorder 27 Post traumatic stress disorder 24 Obsessive compulsive disorder 25 Generalized anxiety disorder 69 Social phobia 16 Alcohol abuse 3 Alcohol dependence 4 Substance abuse 4 Substance dependence 3 Anorexia nervosa 0 Bulimia nervosa 2 Somatization disorder 25 Hypochondriasis 13 Pain disorder 98 Body dysmorphic disorder 9 307 Total of subjects with psychiatric disorders na indicates not applicable. *p < 0.05. **p < 0.01.
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%
CG (n = 463) n
%
χ2
32.69 130 28.07 2.15 49.27 194 41.90 4.96* 9.13 25 5.39 4.64* 6.97 37 7.99 0.29 0.96 9 1.94 1.41 12.5 52 11.23 10.43** 15.86 74 15.98 0.001 9.85 25 5.39 6.31** 6.49 14 3.02 5.89** 5.79 18 3.88 1.74 6.00 32 6.91 0.26 16.58 64 13.82 1.36 3.84 11 2.37 1.60 0.72 5 1.07 0.03 0.96 3 0.64 0.75 0.96 1 0.21 3.15 0.72 1 0.21 2.94 0 1 0.21 na 0.48 4 0.86 0.15 6.00 38 8.20 1.50 3.13 23 4.96 1.85 23.55 93 20.08 1.59 2.16 22 4.75 1.95 73.79 332 71.70 0.55
Analyzing only the psychiatric disorders and sociodemographic characteristics that showed statistically significant differences between groups, logistic regression conducted using the pain group (CLBP versus CG) as the independent variable and the psychiatric diagnosis (e.g., MDEL+ and MDEL-) as the dependent variable showed a greater correlation between prevalence of MDEL and age in CLBP subjects than in CG subjects (Table 6). However, this correlation was not found across the whole sample (χ2 = 0.11, data not shown). In fact, we only found the same positive correlation between agoraphobia (with and without panic) and age in the CLBP group. Correlations were also found with psychiatric disorders and differences between groups in terms of low income, education, and marital status (married). The prevalence of DD, AWP, and AWOP was higher in men with CLBP with respect to their CG counterparts (Table 6). In a subsequent analysis, we investigated the relationship between the presence of psychiatric disorders and the perception of pain in the chronic pain groups, distinguished on the basis of sex. In the CLBP group, women showed higher scores for sensorial (t = 2.22, p = 0.02), affective (t = 1.60; p = not significant), and evaluative (t = 1.12; p = not significant) dimensions and VAS (t = 2.31; p = 0.02) than men did (data not shown). However, the higher pain perception scores found in women in both the CLBP group and the total sample were not reflected when we considered men and women with a psychiatric disorder separately. Indeed, men with MDEL in the CLBP group, but not those in the CG, reported similar pain dimension and intensity scores with women (highlighted in Table 7 by the lack of statistical difference between the sexes). Men with CLBP also reported higher pain intensity in the presence of AWOP. In this case, men had a greater intensity of pain than women did, but only in the CLBP group (Table 7). In contrast, in the presence of DD, men with CG, but not CLBP, showed similar scores for evaluative dimensions of pain to women (Table 7). Intensity of pain (VAS measurement) was positively correlated with the presence of MDEL, DD, AWP, and AWOP, and statistically significant differences between CLBP and CG were noted (Table 6). Compared with the CG, individuals with CLBP showed an increased association between higher intensity, sensorial, and affective dimensions of pain and the presence of DD, AWOP, and AWP (Table 6). MDEL was also associated with an increase in the intensity of pain (VAS) and the sensorial dimension in the CLBP subjects, unlike the CG. The presence of DD was associated with an increase in the intensity and all dimensions of pain, including the evaluative dimension (Table 6).
Differences Between CLBP and CG Subjects in Pain Coping Style Only 533 chronic pain subjects (285 CLBP and 248 CG) were evaluated using the MPI. A greater number of CG subjects than CLBP dropped out (n = 378 versus n = 145, respectively) (χ2 = 71.20; p < 0.0001). Subjects who dropped out at the pain coping assessment stage tended to be older (t = 2.10, p = 0.02), with less education (t = 3.96; p < 0.0001), and were more likely to be widowed (χ2 = 12.53; p = 0.005). No difference between dropouts and continuers was found in terms of IPQ dimensions or intensity of pain. In continuers, as shown in Table 4, the CLBP group reported higher severity and interference of pain than the CG did. CLBP subjects also had higher punishing, lower solicitous, and higher distracting responses with respect to CG patients. The difference between the two groups was even more evident when we compared them using the three categories (clusters) of coping style. There was a higher prevalence of subjects with a dysfunctional coping style in the CLBP group with respect to CG (Table 4), and subjects in the dysfunctional cluster reported high pain severity, high interference and activity distress, low life control, and low activity levels. In other studies, an increase in nonverbal pain communication has also been found in dysfunctional patients (Rusu and Hasenbring, 2008), albeit in ID subjects. We, on the other © 2015 Wolters Kluwer Health, Inc. All rights reserved.
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The Journal of Nervous and Mental Disease • Volume 203, Number 8, August 2015
Psychiatric Disorders in CLBP
TABLE 6. Sociodemographic Variables and Perception of Pain in Relationship With the Difference in Prevalence of Psychiatric Disorders in the CLBP Compared With CG Subjects CLBP/CG MDEL Age Education Males Low income married Sensorial D. Affective D. Evaluative D. VAS pain Tolerance SSAS
DD
SR
AWOP
AWP
Coef
χ
Coef
χ
Coef
χ
Coef
χ
Coef
χ2
0.33 0.17 0.86 0.05 0.04 0.26 0.26 0.26 0.29 0.17 0.23
5.76** 0.77 2.29 0.21 0.30 3.80* 3.77 3.72 4.50* 0.91 1.82
0.53 0.31 0.11 0.21 0.08 0.59 0.52 0.53 0.61 0.29 0.45
3.73 0.75 3.83* 2.93 1.43 4.80* 3.83* 3.84* 5.20* 0.82 2.05
0.29 −0.44 0.04 0.10 0.02 0.24 0.29 0.27 0.28 0.15 0.26
1.81 1.97 0.58 0.65 0.07 1.30 1.94 1.62 1.70 0.31 1.09
0.67 −0.11 0.13 0.09 0.04 0.58 0.61 0.51 0.68 0.26 0.38
6.31** 0.10 5.25* 0.50 1.33 4.74* 5.27* 3.61 6.41** 0.71 1.60
0.88 0.38 0.11 0.16 0.05 0.80 0.76 0.66 0.86 0.59 0.56
6.60** 0.76 4.29* 1.65 0.59 5.57** 5.05* 3.77 6.40** 2.18 2.16
2
2
2
2
D indicates dimension of pain. *Logistic regression analysis: p < 0.05. **Logistic regression analysis: p < 0.01. ***Logistic regression analysis: p < 0.001.
hand, found that ID, along with AC, is more prevalent in the CG, whereas CLBP subjects were more likely to be classed as DYS (Table 4). However, like Rusu and Hasenbring (2008), we found a greater association between anxiety disorder and DYS pain coping style in the CLBP group, as compared with the CG (Table 8). Our results also show a greater prevalence of agoraphobia with panic disorder in the DYS cluster of CLBP patients than in their CG counterparts (Table 8), which could contribute to the lower general activity level (in particular away from home) seen in CLBP than in CG (Table 4). A greater prevalence of men and a lower income characterized the ID CLBP cluster, as compared with CG patients with the same pain coping style (Table 8). Differences were also found for the AC coping style cluster, as those from the CLBP group were predominantly married, unlike those in the CG, who were mostly single (Table 8).
DISCUSSION AND CONCLUSIONS Patients treated at a tertiary pain clinic typically have a long history of therapeutic failures and may experience a greater number of psychiatric comorbidities compared with those who turn to secondary care. This consideration is confirmed by our results, which, in fact, show a far higher prevalence of psychiatric comorbidities than some previous
studies (Mayr et al., 2003; Reme et al., 2011). In our investigation, individuals with CLBP had a prevalence of current and lifetime psychiatric disorders of approximately 74%, as compared with the 38% reported in a study of subjects sick-listed for unspecific LBP in secondary care (Reme et al., 2011). The presence of lesions that justify pain is another factor that affects the prevalence of psychiatric comorbidity (Magni and Merskey, 1987). However, our CLBP patients referred experiencing persistent pain, even after anesthetic and invasive analgesic procedures, that resisted all types of analgesic drug treatment. As their persistent pain could not be explained by lesion worsening or other complications, it may be that the very high prevalence of psychiatric disorders played a role in their suffering. That being said, there was no difference between our CLBP and CG subjects in the global prevalence of psychiatric disorders, but there were differences between the two groups in the prevalence of some specific psychiatric disorders. Indeed, CLBP was associated with a higher prevalence of MDEL, DD, SR, AWOP, and AWP with respect to CG (Table 5). This difference affected the perception of pain and was also linked to the sociodemographic characteristics of each group. A higher prevalence of MDEL in such subjects has been shown before (Licciardone et al., 2012), but we also show that the prevalence of MDEL, AWOP, and AWP in CLBP increases with increasing age,
TABLE 7. Influence of the Presence of Psychiatric Disorders in the Perception of Pain in CLBP and CG Subjects Distinguished on the Basis of Sex MDEL Sensorial CLBP CG
Affective
Evaluative
DD
AWOP
Evaluative
VAS
M
F
t
M
F
t
M
F
t
M
F
t
M
F
t
0.38 0.29
0.42 0.38
1.26 3.36***
0.42 0.31
0.44 0.43
0.66 3.19**
0.50 0.30
0.49 0.42
0.29 2.78**
0.39 0.43
0.54 0.44
2.24* 0.07
8.91 7.00
7.66 7.82
2.13* 0.67
*Logistic regression analysis: p < 0.05. **Logistic regression analysis: p < 0.01. ***Logistic regression analysis: p < 0.001.
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TABLE 8. Sociodemographic Characteristics and Psychiatric Disorders Differences in the CLBP and CG Subjects Distinguished on the Basis of MPI Coping Style AC (n = 162) Total Sex Males Females Marital status Married Divorced Single Widower Social status High Medium Low MDEL DD SR AWOP AWP
CLBP
CG
92 (56.7)
70 (43.2)
43 (46.7) 49 (53.2)
25 (35.7) 45 (64.2)
78 (84.7) 5 (5.4) 3 (3.2) 6 (6.5)
41 (58.5) 4 (5.7) 24 (34.2) 1 (1.4)
2 (1.2) 78 (48.1) 12 (7.4) 37 (22.8) 6 (3.7) 9 (5.5) 4 (2.4) 1 (0.6)
2 (1.2) 62 (38.2) 6 (3.7) 23 (14.1) 3 (1.8) 5 (3.0) 5 (3.0) 3 (1.8)
DYS (n = 124) χ2
ID (n = 191) χ2
CLBP
CG
81 (65.3)
43 (34.6)
1.98
24 (29.6) 57 (70.3)
9 (20.9) 34 (70.0)
14.15**
51 (41.1) 9 (7.2) 9 (7.2) 12 (9.6)
25 (20.1) 6 (4.8) 7 (5.6) 5 (4.0)
0.26 0.77 0.34 0.70 0.60 1.69
6 (4.8) 51 (41.1) 24 (19.3) 51 (41.1) 9 (7.2) 15 (12.0) 19 (15.3) 16 (12.9)
2 (1.6) 32 (25.8) 9 (7.2) 23 (18.5) 2 (1.6) 6 (4.8) 7 (5.6) 3 (2.4)
χ2
CLBP
CG
108 (56.5)
83 (43.4)
1.08
40 (37.0) 68 (62.9)
20 (24.0) 63 (75.9)
3.64*
0.79
52 (27.2) 16 (8.3) 25 (13.0) 15 (7.8)
49 (25.6) 6 (3.1) 23 (12.0) 5 (2.6)
2.96
0.86 1.42 1.54 1.30 1.00 3.74*
6 (3.1) 67 (35.0) 35 (18.3) 49 (25.6) 13 (6.80) 8 (4.1) 4 (2.0) 4 (2.0)
2 (1.0) 72 (37.6) 9 (4.7) 39 (20.4) 5 (2.6) 11 (5.7) 5 (2.6) 2 (1.0)
6.70* 0.04 2.07 1.18 0.52 0.29
Data are presented as n (%). *p < 0.05. **p < 0.01.
much more so than in other forms of chronic pain (Table 6). Our data therefore highlight an increased risk of depressive episodes and agoraphobia with advancing age in CLBP, but not in CG. As illustrated in Table 1, this risk is not related to the persistence of pain, as no evident differences were seen between the two groups in the time since pain onset. Sex, however, does appear to play a role, and there was a greater susceptibility of CLBP men to dysthymia, AWOP, and AWP with respect to CG men (Table 6). Our results show that the presence of MDEL and AWOP changes the perception of pain in men differently between the two groups. Indeed, as shown in the Table 7, men in the CLBP group, but not in the CG, show an increase in dimensions of pain in the presence of MDEL, and a greater pain intensity of pain in the presence of AWOP. Although previous research has found a relationship between psychosocial and sex in the perception of pain (Racine et al., 2012), evidence is still scarce on the whole. We, however, show that MDEL and AWOP do exert an influence on pain perception in male CLBP subjects. We also show an important difference between groups in the prevalence of SR, which was more closely associated with CLBP (Table 5). The association between SR and psychopathology has been studied before in CLBP patients with comorbid current depression (Cheatle, 2014). However, we found no differences in the perception of pain in the presence of SR (Table 6). Using the DCPR criteria to investigate psychosomatic dimensions revealed no differences between the two groups, with the exception of somatic amplification (SSAS), which was higher in CG patients (Table 3). Like Reme et al. (2011), we found a high rate of SPD (the third most frequent in our study) in CLBP patients, but they did not differ in this respect from CG patients (Table 5). This lack of difference in the tendency to somatize between the two groups was confirmed by the similar prevalence of somatoform disorders, as 638
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investigated by the MINI plus (Table 5). This allows us to conclude that the tendency to somatization is a general phenomenon, rather than being associated with a particular form of chronic pain. Nevertheless, considering the difference in the SSAS values seen, it is possible that a subset of the CG could explain the greater presence of somatization by increasing the SSAS scores. Sensorial encoding in the two groups was very similar, as highlighted by the cold-pain perception threshold (Table 3). However, slight differences between CLBP and GC subjects were seen in pain tolerance. Perception of pain was particularly different between groups in terms of clinical pain, and CLBP subjects perceived more severe pain with higher sensorial, affective, and evaluative dimensions than CG subjects did (Table 3). The groups also coped differently with pain, with CLBP patients being more likely to adopt a DYS coping style than the CG patients were (Table 4). A role in DYS and ID has been ascribed to operant conditioning (Rusu and Hasenbring, 2008), and our results suggest a disruptive relationship between CLBP subjects and their spouses characterized by higher punishing, lower solicitous, and higher distracting responses than in CG-affected relationships (Table 4). The DYS cluster was also associated with a greater prevalence of AWP in CLBP patients (Table 8). This association between a DYS coping style and agoraphobia seems to exacerbate the pain perceived and increase disability, restricting the socialization of subjects with CLBP. Indeed, our study shows a close relationship between pain intensity, presence of agoraphobia, lifetime depression, and dysfunctional coping style in CLBP that can also be affected by the age and sex of the subject. We therefore agree with a consensus group set up to promote health programs for CLBP in Mexico, which suggested that patients be offered a multimodal program to counteract inadequate pain management. Indeed, pain has severe physical, psychoaffective, and socioeconomic repercussions, not only for patients but also for their families © 2015 Wolters Kluwer Health, Inc. All rights reserved.
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and the public health services (Guevara-López et al., 2011). Tertiary pain clinics therefore need to focus on multimodal psychological and psychiatric treatment to prevent greater disability, suffering, and SR in patients with CLBP. DISCLOSURE The authors declare no conflicts of interest. REFERENCES Airaksinen O, Brox JI, Cedraschi C, Hildebrandt J, Klaber-Moffett J, Kovacs F, Mannion AF, Reis S, Staal JB, Ursin H, Zanoli G (2006) COST B13 Working Group on Guidelines for Chronic Low Back Pain. Chapter 4. European guidelines for the management of chronic nonspecific low back pain. Eur Spine J. 15(suppl 2):S192–S300.
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and risk of transition to chronicity in men with first onset low back pain. Pain Med. 11:1391–1400. Sheehan DV, Lecrubier Y, Sheehan KH, Amorim P, Janavs J, Weiller E, Hergueta T, Baker R, Dunbar GC (1998) The Mini-International Neuropsychiatric Interview (M.I.N.I.): The development and validation of a structured diagnostic psychiatric interview for DSM-IV and ICD-10. J Clin Psychiatry. 59(suppl 20):22–33.
Von Korff M, Crane P, Lane M, Miglioretti DL, Simon G, Saunders K, Stang P, Brandenburg N, Kessler R (2005) Chronic spinal pain and physical-mental comorbidity in the United States: Results from the national comorbidity survey replication. Pain. 113:331–339. Waddell C (2004) The back pain revolution 2nd ed. Edinburgh: Churchill Livingstone.
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Chronic Low Back Pain Perception and Coping With Pain in the Presence of Psychiatric Comorbidity Antonella Ciaramella, MD* and Paolo Poli, MD† Abstract: This retrospective study investigated the influence of psychiatric comorbidity on pain perception and coping with pain in tertiary pain clinic patients, 427 treated for chronic low back pain (CLBP) and 629 for other forms of chronic pain (CG). No differences in psychosomatic dimensions were found between the two groups, but Italian Pain Questionnaire dimensions and intensity scores (t = 7.35; p < 0.0001) were higher in CLBP than in CG subjects. According to the Mini-International Neuropsychiatric Interview, CLBP patients also had a higher prevalence of lifetime major depressive episodes (χ2 = 4.96; p < 0.05), dysthymic disorder (χ2 = 4.64; p < 0.05), suicide risk (χ2 = 10.43; p < 0.01), and agoraphobia (χ2 = 6.31; p < 0.05) than CG patients did. The Multidimensional Pain Inventory showed a close association between CLBP and both agoraphobia (χ2 = 3.74; p < 0.05) and dysfunctional coping style (χ2 = 8.25; p < 0.01), which increased disability. Both agoraphobia and lifetime depression were associated with an overall increase in dimensions and pain intensity in CLBP, but not in CG. Key Words: CLBP, psychiatric disorders, sex, coping, pain perception, agoraphobia, DCPR criteria, tertiary care (J Nerv Ment Dis 2015;203: 632–640)
C
hronic low back pain (CLBP) is a condition that is both caused and maintained by the interaction and mutual influence of several biological, psychological and social factors (Dersh et al., 2001; Waddell, 2004). In CLBP, there is a high degree of comorbidity, and reports of additional somatic and psychological symptoms and complaints are common (Carnes et al., 2007; Hagen et al., 2006; Von Korff et al., 2005). The prevalence of comorbid psychiatric disorders is often assessed and considered, but in most cases, questionnaires, rather than diagnostic interviews, are the assessment tool of choice (e.g., Currie and Wang, 2004; Manchikanti et al., 2002; Mok and Lee, 2008). Studies that have been conducted via diagnostic interviews show a consistently high prevalence of psychiatric comorbidities in CLBP, ranging from 41% to 99% (Atkinson et al., 1991; Dersh et al., 2006; Kinney et al., 1993; Polatin et al., 1993; Reich et al., 1983). The most common comorbid conditions are somatoform disorders, affective disorders, and substance abuse disorders, with major depression being the most common single diagnosis (Kinney et al., 1993; Polatin et al., 1993). There is also a significantly greater prevalence of psychiatric disorders in those reporting CLBP compared with those without CLBP in the general population, as seen across 17 countries in global mental health surveys (Demyttenaere et al., 2007). Furthermore, psychosocial risk factors—so-called pain-prone factors—are partially responsible for lengthening the duration of pain syndromes, which can also be exacerbated by associations with life events and lack of coping strategies. A lifetime history of major depression or a major anxiety disorder may represent potential psychosocial *Aplysia onlus, GIFT Institute of Integrative Medicine; and †Pain Therapy Unit, Azienda Ospedaliero-Universitaria Pisana, Pisa, Italy. Send reprint requests to Antonella Ciaramella, MD, Aplysia onlus, GIFT Institute of Integrative Medicine, p.za Cairoli, 12, 56127 Pisa, Italy. E-mail: [email protected]. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved. ISSN: 0022-3018/15/20308–0632 DOI: 10.1097/NMD.0000000000000340
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risk factors for transition to chronic pain in men with first-onset low back pain (LBP). These patients may benefit from referral for more intensive rehabilitation, and screening for lifetime depressive or anxiety disorders to identify individuals at higher risk is therefore advisable (Shaw et al., 2010). Indeed, somatic assessment has revealed that the fewer the structural and neurological deficits in CLBP, the more psychiatric symptoms are present (Mayr et al., 2003). This may help explain why 85% of CLBP disorders have no identifiable cause, being classed as “nonspecific CLBP” and thereby leaving a large diagnostic and management vacuum (O'Sullivan, 2005). Vice versa, the number of pain complaints has been found to increase the likelihood of psychopathology (Katon and Sullivan, 1990), and more widespread pain has been associated with disability (Kamaleri et al., 2008). Concurrent psychopathology is likely to worsen prognosis (Linton, 2000) and outcome in CLBP (Dersh et al., 2007) and increase the burden on the health care services (Engel et al., 1996). Clinical guidelines therefore stress the importance of screening for concurrent psychopathology in these patients (Airaksinen et al., 2006). Although a strong association between CLBP and anxiety and depression has been found (Sagheer et al., 2013), we are still lacking knowledge regarding their impact on the affective dimension of pain, and few studies have investigated the influence of psychiatric comorbidities on pain management in a tertiary care setting. According to Chris et al. (2007), rather than changing the intensity of pain, the focus of a tertiary care multidisciplinary pain management program should be to reduce the intrusiveness of the emotional component of pain. It is therefore vital to evaluate the affective component of pain in such patients. The primary objective of this study was to reveal any differences in sociodemographic characteristics, perception of pain, and/or psychosomatic dimensions between CLBP and a control group comprising patients with other forms of chronic pain (CG), all treated in a tertiary pain clinic. We also investigated the prevalence of psychiatric comorbidities, according to the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) and International Classification of Diseases (ICD-10), in both groups and evaluated their impact on perception and coping with pain.
METHODS Participants and Study Design This retrospective study looked at 1056 subjects treated for chronic pain (427 CLBP and 629 GP) at a tertiary pain clinic (at the Azienda Ospedaliero-Universitaria di Pisana, Italy). After referral to the unit, subjects were evaluated by both an anesthetist, expert in pain therapy (P.P.), and a psychiatrist (A.C.), for pain threshold and perception assessment. All patients investigated (CLBP and CG) had already been unsuccessfully given surgical, anesthetic, and analgesic drug treatment, and no variations in spinal radiological, ultrasound, nuclear magnetic resonance, or inflammatory blood parameters in their medical records were able to explain the persistence of pain. All patients were evaluated using a multidimensional pain questionnaire (Italian Pain Questionnaire [IPQ]; see Measures section) to assess the affective dimensions of their pain. Some of them agreed to be assessed for
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The Journal of Nervous and Mental Disease • Volume 203, Number 8, August 2015
Psychiatric Disorders in CLBP
psychiatric disorders using a semistructured interview, the MiniInternational Neuropsychiatric Interview (MINI) Plus (Ciaramella et al., 2004), administered by a psychiatrist with at least 1 year's training in use of the tool. After psychiatric assessment, patients were asked to self-assess pain coping through the Multidimensional Pain Inventory (MPI) (see below), but some refused to continue the (rather lengthy) evaluation procedure at this point. Therefore, the data on psychiatric disorders and coping with pain are not available for all patients (see Results). A classification of CLBP includes different clinical forms (O'Sullivan, 2005); we defined CLBP as back pain persisting for longer than 7 to 12 weeks (Andersson, 1999). All subjects had a history of at least one treatment failure, with 55% of CLBP patients reporting persistent pain after laminectomy and 11% after spinal stabilization surgery (failed back surgery syndrome). The CG comprised subjects with various forms of chronic pain (Table 1) as a sample of the general population referred to the multidisciplinary pain center. All principles of the Helsinki declaration were adhered to, and all subjects provided informed written consent before the evaluation.
answers and covers 23 axis 1 disorders. In the multiaxial system of DSM-IV, axis I disorders include all major mental disorders, as well as developmental and learning disorders. The MINI interview usually takes 15 to 20 minutes and has high reliability and validity (Sheehan et al., 1998). We used the Italian version of MINI Plus (Ciaramella et al., 2004), which features questions on rule-outs (e.g., depressive reaction due to grief ), disorder subtyping (e.g., somatoform pain disorder [SPD] related to psychological factors or somatic condition), and chronology (e.g., when was the first time you experienced a panic attack) and includes modules for somatization disorders (e.g., hypochondriasis and SPD). MINI Plus further uses different timeframes for various disorders: current, past, or lifetime, that is, “the preceding 2 weeks (major depression), the past month (panic disorder, social phobia, obsessive compulsive disorder, PTSD), the past 12 months (alcohol dependency/ abuse), or ongoing at the time of interview with no further time reference (mania, agoraphobia, generalized anxiety disorder, psychotic disorders, somatisation disorders, anorexia, bulimia).” In this way, MINI differs from most other diagnostic interviews that usually ask for symptoms within the past 12 months.
Measures
Self-Assessment
Clinical Assessment
The somatosensory amplification scale The Somatosensory Amplification Scale (SSAS) is a 10-item self-report questionnaire that measures hypervigilance to body sensations, the tendency to select weak and infrequent sensations, and a disposition to react to somatic sensations with effects on cognitions that intensify them and make them more alarming and disturbing. Patients were asked to indicate how much each symptom had bothered them in the preceding 24 hours using a 5-point scale, with responses ranging from “not at all” to “extremely.” A higher total score indicates greater symptom amplification (Barsky et al., 1990).
Cold pressure test The nondominant limb was immersed in icy water (−0, 5–2°C) for a maximum of 240 seconds after temperature standardization, via limb immersion, in water at body temperature (37°C ± 0.5°C) for 240 seconds. We identified the pain threshold as the time from the immersion of the limb in the icy water until the first pain sensation. We defined pain tolerance as the time from the immersion of the limb in the icy water until the limb retracted intolerable pain (Wolff, 1984). The MINI was applied as the structured diagnostic interview (Sheehan et al., 1998) for DSM-IV (American Psychiatric Association, 1994) and ICD-10 (World Health Organization, 1993) assessing psychiatric disorders. It is based on “yes” and “no”
Italian pain questionnaire The IPQ (in the form of Questionario Italiano Del Dolore; De Benedittis et al., 1988) derives from the McGill Pain Questionnaire; it uses the factorial structure proposed by Melzack and Torgerson
TABLE 1. Clinical Factors in CLBP Compared With CG Subjects Evaluated in a Tertiary Pain Clinic CLBP (n = 427) n (%) Onset of pain, mos Pain syndromes FBSS LBP PP IP PHN CRPS Arthrosis Headache Facial pain Fibromyalgia Cancer Others Pain comorbidity Current treatment of pain Current treatment of psychiatric disorders
Mean (SD)
CG (n = 629) n (%)
101.76 (106.43)
Mean (SD)
t/χ2
102.42 (132.24)
0.06
283 (66.27) 144 (33.72)
324 (76.22) 328 (77.16) 178 (38.84)
39 (6.20) 24 (3.80) 39 (6.17) 25 (4.03) 7 (1.18) 145 (23.27) 46 (7.36) 65 (8.78) 82 (13.77) 157 (24.94) 465 (74.43) 490 (77.95) 232 (36.70)
0.11 0.88 0.11
t is value of t-test analysis for unpaired data. χ2 is chi value of square analysis. FBSS indicates failed back surgery syndrome; PP, phantom pain; IP, ischemic pain; PHN, postherpetic neuralgia; CRPS, complex regional pain syndrome.
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(1971) made up of three factors or classes (Sensorial, Affective, and Evaluative). The visual analog scale (VAS) consists of a line, usually 10 cm long, whose ends are labeled as the extremes of pain (no pain to pain as bad as it could be). Patients are asked to indicate which point along the line best represents their pain intensity. The distance from the no pain end to the mark made by the patients is the intensity score (Jensen and Karoly, 1992).
The Toronto alexithymia scale The Toronto Alexithymia Scale (TAS) is a 20-item instrument that is one of the most commonly used measures of alexithymia. Alexithymia refers to people who have trouble identifying and describing emotions and who tend to minimize emotional experience and focus attention externally (Bagby et al., 1994).
Statistical Analysis Multidimensional pain inventory The MPI was developed to fill a widely recognized void in the assessment of clinical pain. Three parts of the inventory, composed of 12 scales, examine the impact of pain on the patients' lives, the responses of others to the patients' communications of pain, and the extent to which patients participate in common daily activities. We used the Italian version of MPI (Ferrari et al., 2000). The MPI Program software developed by Rudy (2004) allows the dimensions to be clustered into categories of related maladaptive pain coping according to the distinct profiles identified by Turk and Rudy, 1988. In this study, we used three principal categories: Dysfunctional (DYS), Interpersonally Distressed (ID), and Adaptive Copers (AC). DYS patients score high on pain severity, life interference, and emotional distress but low on perceived control and activity. ID patients additionally report low level of social support. In contrast, AC patients show low level of pain, interference, and distress but high levels of life control and activity (Rusu and Hasenbring, 2008). The irritability depression anxiety scale The Irritability Depression Anxiety Scale (IDAS) is a 14-item self-administered assessment that includes four items to assess irritability, five items to measure anxiety, and five items to evaluate depression. The IDAS is a validated instrument capable of distinguishing between depressive and anxiety disorders. The IDAS investigates depression not only with symptoms of negative mood but also using the absence of positive mood (Snaith et al., 1978).
The data were analyzed using StatView 5.0 software (SAS Institute Inc; Landau and Rabe-Hesketh, 1999). After the application of Kolmogorov-Smirnov test, which gives details about the Gaussian distribution of the data, we investigated the differences between CLBP and CG using t-test analysis. Differences in the frequency of psychiatric disorders among various diagnostic pain groups were assessed with chi-square analysis using Fisher exact test for a small sample. Logistic regression analysis was performed considering only the psychiatric disorder that showed statistical differences between groups as a dependent variable. This last analysis was performed to evaluate differences in pain perception variables, tolerance of painful stimulus, and somatosensory amplification between the two groups, distinguished on the basis of presence of psychiatric disorders according to axis I categories of DSM-IV. Chi-square analysis was performed to measure differences in sociodemographic variables and psychiatric disorders between groups, distinguished on the basis of maladaptive pain related coping. Data are presented as mean ± SD, with a level of significance at p < 0.05.
RESULTS Differences in Sociodemographic and Clinical Factors Between CLBP and CG Subjects A total of 427 CLBP subjects were compared with 629 subjects with other forms of chronic pain as control (CG). Table 1 shows the percentage of pain syndromes included in the CG.
TABLE 2. Sociodemographic Factors in CLBP Compared With CG Subjects Evaluated in a Tertiary Pain Clinic CLBP (n = 427) n (%) Age Education, yrs Sex Males Females Marital status Married Divorced Single Widower Income High Medium Low
Mean (SD)
CG (n = 629) n (%)
60.97 (13.75) 8.60 (4.53)
Mean (SD)
t/χ2
52.66 (17.08) 11.37 (5.13)
8.31**** 6.06****
167 (39.32) 260 (60.67)
201 (31.95) 428 (68.04)
4.82*
278 (65.10) 42 (9.83) 42 (9.83) 65 (15.22)
371 (58.98) 44 (6.99) 151 (24.00) 63 (10.01)
11.56**
16 (3.74) 289 (67.68) 122 (28.57)
13 (20.06) 535 (85.05) 81 (12.87)
13.08***
t is value of t-test analysis for unpaired data. χ is chi value of square analysis. *p < 0.05. **p < 0.01. ***p < 0.001. ****p < 0.0001. 2
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The Journal of Nervous and Mental Disease • Volume 203, Number 8, August 2015
Differences Between CLBP and CG Subjects in the Perception of Pain and Psychosomatic Dimensions
TABLE 3. Perception of Spontaneous Pain, Psychosomatic Factors, Threshold, and Tolerance of Pain Induced by Cold Water Stimulus in CLBP Compared With CG Subjects Evaluated in a Tertiary Pain Clinic
Sensorial dimension Affective dimension Evaluative dimension VAS Cold pain threshold, sec Cold pain tolerance, sec Irritability (IDAS) Depression (IDAS) Anxiety (IDAS) SSAS total scoring Toronto Alexitymia Scale 20 total scoring
CLBP (n = 427)
CG (n = 629)
t
0.40 (0.16) 0.39 (0.22) 0.46 (0.28) 8.04 (2.03) 22.62 (25.50) 63.61 (38.82) 3.53 (2.82) 6.56 (2.95) 6.23 (3.16) 14.48 (6.34) 50.89 (13.03)
0.34 (0.15) 0.36 (0.22) 0.37 (0.25) 7.35 (2.13) 18.93 (20.41) 56.30 (39.50) 3.69 (2.62) 6.92 (3.13) 5.82 (3.32) 15.97 (6.68) 49.22 (14.27)
5.95*** 2.15* 5.95*** 5.21*** 1.73 2.07* 0.42 0.82 0.88 2.91** 1.02
Psychiatric Disorders in CLBP
Pain perception was investigated using two different approaches. In the first, clinical pain was investigated using a multidimensional questionnaire (IPQ) in which spontaneous (or clinical) pain is evaluated in the sensorial, affective, and evaluative dimensions, and its intensity, on a VAS. As part of the psychophysical analysis to assess pain threshold and tolerance, we also evaluated the perception of pain through the application of cold water as a painful stimulus (cold pressure test). Sensorial and evaluative, more so than affective, dimensions were higher in CLBP than in CG subjects. CLBP subjects reported more severe pain than CG subjects did (Table 3). However, across all subjects investigated (n = 1056), the value of some dimensions were strongly dependent on age. In fact, using age as the dependent variable in multiple regression analysis, we found a strong positive correlation with evaluative dimensions (t = 3.66, p = 0.0003) and a smaller positive relationship with sensorial dimensions of pain (t = 2.21, p = 0.02). Pain dimensions and intensity were both lower in male subjects (more markedly so in the CLBP group). Bonferroni's correction showed a statistically significant reduction in scores for sensorial (p = 0.007), affective (p = 0.01), and evaluative (p = 0.04) dimensions and intensity of pain (VAS) (p = 0.01) in men with respect to women. The higher values found for all dimensions and pain intensity in CLBP subjects is not sufficiently explained by demographic data, as these factors have different impacts on the perception of pain. The higher intensity of pain in the CLBP group was confirmed using the MPI (Table 4), but differences in the negative perception of spontaneous pain were not confirmed through induction of a cold painful stimulus. Indeed, CLBP subjects showed a higher tolerance (better endurance) to the cold pressure test than the CG did (Table 3). In accordance with the Diagnostic Criteria for Psychosomatic Research (DCPR; Porcelli and Rafanelli, 2010), we investigated
t is value of t-test analysis for unpaired data. Data are presented as mean (SD). *p < 0.05. **p < 0.01. ***p < 0.0001.
As shown in Table 2, the CLBP group is older, with a lower education level, and features a higher prevalence of men than the CG does. More CLBP patients were married and/or on a low income. No differences were found between groups in terms of time since pain onset, number of other chronic pain comorbidities, current pain treatment, or psychiatric comorbidity (Table 1).
TABLE 4. Pain Coping and Coping Style Disability in CLBP Compared With CG Subjects Evaluated in a Tertiary Pain Clinic CLBP (n = 285) Mean (SD) MPI dimensions Pain Severity Interference Life Control Affective Distress Social Support Punishing Responses Solicitous Responses Distracting Responses Household chores Outdoor work Activity away from home Social activities General activity level MPI coping style DYS ID AC
CG (n = 248)
n
%
4.58 (1.25) 4.28 (1.40) 3.52 (1.41) 3.32 (1.22) 4.16 (1.65) 2.53 (2.10) 3.05 (1.83) 3.02 (2.82) 3.12 (1.79) 2.01 (1.94) 1.73 (1.52) 2.18 (2.40) 2.18 (1.17)
Mean (SD)
n
4.01 (1.40) 3.55 (1.48) 3.39 (1.43) 3.20 (1.27) 4.41 (1.64) 1.41 (1.41) 3.50 (1.48) 2.60 (1.55) 3.61 (1.94) 1.69 (1.75) 2.23 (1.41) 2.41 (1.44) 2.51 (1.18) 82 108 95
28.77 37.89 33.33
t/χ2
%
4.60*** 5.80*** 0.28 1.05 1.77 7.06*** 3.06* 2.87* 2.81* 1.78 3.57** 1.17 3.02* 45 108 95
18.14 43.54 38.30
8.25*
t is value of t-test analysis for unpaired data. χ is chi value of square analysis. *p < 0.01. **p < 0.001. ***p < 0.0001. 2
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depression, anxiety, and irritability using the IDAS; alexithymia using the TAS; and somatosensory amplification the SSAS (Fava and Sonino, 2000). Of these, only the global SSAS showed any intergroup difference, being lower in the CLBP group than in the CG (Table 3).
Differences Between CLBP and CG Subjects in Psychiatric Disorder Comorbidity Only 879 subjects (416 CLBP and 463 CG) were investigated for psychiatric disorders with a semistructured interview, as, globally, there were 176 (n = 11 CLBP and n = 165 CG) dropouts at the psychiatric assessment stage. The CG displayed a higher dropout rate than the CLBP group did (χ2 = 102.47; p < 0.0001), but no differences were found between dropouts and continuers in age, sex, marital status, income, IPQ dimensions, or VAS pain scores. The number and percentages of psychiatric comorbidities are shown in Table 5. Lifetime prevalences of major depressive episodes, manic and hypomanic episodes, panic disorder, suicide risk (SR), generalized anxiety, and somatoform disorders were investigated using the MINI plus. This showed that CLBP patients had a greater prevalence of lifetime major depressive episodes (MDEL) and dysthymic disorder (DD), as well as higher scores for SR and agoraphobia, with and without panic (AWP and AWOP, respectively), than CG did (Table 5).
TABLE 5. Psychiatric Disorders Assessed According to DSM-IV in CLBP Compared With CG Subjects CLBP (n = 416) n Major depressive episode current 136 Major depressive episode lifetime 205 Dysthymic disorder 38 Hypomanic episode 29 Manic episode 4 Suicidal risk 52 Panic disorder 66 Agoraphobia without panic disorder 41 Agoraphobia with panic disorder 27 Post traumatic stress disorder 24 Obsessive compulsive disorder 25 Generalized anxiety disorder 69 Social phobia 16 Alcohol abuse 3 Alcohol dependence 4 Substance abuse 4 Substance dependence 3 Anorexia nervosa 0 Bulimia nervosa 2 Somatization disorder 25 Hypochondriasis 13 Pain disorder 98 Body dysmorphic disorder 9 307 Total of subjects with psychiatric disorders na indicates not applicable. *p < 0.05. **p < 0.01.
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%
CG (n = 463) n
%
χ2
32.69 130 28.07 2.15 49.27 194 41.90 4.96* 9.13 25 5.39 4.64* 6.97 37 7.99 0.29 0.96 9 1.94 1.41 12.5 52 11.23 10.43** 15.86 74 15.98 0.001 9.85 25 5.39 6.31** 6.49 14 3.02 5.89** 5.79 18 3.88 1.74 6.00 32 6.91 0.26 16.58 64 13.82 1.36 3.84 11 2.37 1.60 0.72 5 1.07 0.03 0.96 3 0.64 0.75 0.96 1 0.21 3.15 0.72 1 0.21 2.94 0 1 0.21 na 0.48 4 0.86 0.15 6.00 38 8.20 1.50 3.13 23 4.96 1.85 23.55 93 20.08 1.59 2.16 22 4.75 1.95 73.79 332 71.70 0.55
Analyzing only the psychiatric disorders and sociodemographic characteristics that showed statistically significant differences between groups, logistic regression conducted using the pain group (CLBP versus CG) as the independent variable and the psychiatric diagnosis (e.g., MDEL+ and MDEL-) as the dependent variable showed a greater correlation between prevalence of MDEL and age in CLBP subjects than in CG subjects (Table 6). However, this correlation was not found across the whole sample (χ2 = 0.11, data not shown). In fact, we only found the same positive correlation between agoraphobia (with and without panic) and age in the CLBP group. Correlations were also found with psychiatric disorders and differences between groups in terms of low income, education, and marital status (married). The prevalence of DD, AWP, and AWOP was higher in men with CLBP with respect to their CG counterparts (Table 6). In a subsequent analysis, we investigated the relationship between the presence of psychiatric disorders and the perception of pain in the chronic pain groups, distinguished on the basis of sex. In the CLBP group, women showed higher scores for sensorial (t = 2.22, p = 0.02), affective (t = 1.60; p = not significant), and evaluative (t = 1.12; p = not significant) dimensions and VAS (t = 2.31; p = 0.02) than men did (data not shown). However, the higher pain perception scores found in women in both the CLBP group and the total sample were not reflected when we considered men and women with a psychiatric disorder separately. Indeed, men with MDEL in the CLBP group, but not those in the CG, reported similar pain dimension and intensity scores with women (highlighted in Table 7 by the lack of statistical difference between the sexes). Men with CLBP also reported higher pain intensity in the presence of AWOP. In this case, men had a greater intensity of pain than women did, but only in the CLBP group (Table 7). In contrast, in the presence of DD, men with CG, but not CLBP, showed similar scores for evaluative dimensions of pain to women (Table 7). Intensity of pain (VAS measurement) was positively correlated with the presence of MDEL, DD, AWP, and AWOP, and statistically significant differences between CLBP and CG were noted (Table 6). Compared with the CG, individuals with CLBP showed an increased association between higher intensity, sensorial, and affective dimensions of pain and the presence of DD, AWOP, and AWP (Table 6). MDEL was also associated with an increase in the intensity of pain (VAS) and the sensorial dimension in the CLBP subjects, unlike the CG. The presence of DD was associated with an increase in the intensity and all dimensions of pain, including the evaluative dimension (Table 6).
Differences Between CLBP and CG Subjects in Pain Coping Style Only 533 chronic pain subjects (285 CLBP and 248 CG) were evaluated using the MPI. A greater number of CG subjects than CLBP dropped out (n = 378 versus n = 145, respectively) (χ2 = 71.20; p < 0.0001). Subjects who dropped out at the pain coping assessment stage tended to be older (t = 2.10, p = 0.02), with less education (t = 3.96; p < 0.0001), and were more likely to be widowed (χ2 = 12.53; p = 0.005). No difference between dropouts and continuers was found in terms of IPQ dimensions or intensity of pain. In continuers, as shown in Table 4, the CLBP group reported higher severity and interference of pain than the CG did. CLBP subjects also had higher punishing, lower solicitous, and higher distracting responses with respect to CG patients. The difference between the two groups was even more evident when we compared them using the three categories (clusters) of coping style. There was a higher prevalence of subjects with a dysfunctional coping style in the CLBP group with respect to CG (Table 4), and subjects in the dysfunctional cluster reported high pain severity, high interference and activity distress, low life control, and low activity levels. In other studies, an increase in nonverbal pain communication has also been found in dysfunctional patients (Rusu and Hasenbring, 2008), albeit in ID subjects. We, on the other © 2015 Wolters Kluwer Health, Inc. All rights reserved.
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The Journal of Nervous and Mental Disease • Volume 203, Number 8, August 2015
Psychiatric Disorders in CLBP
TABLE 6. Sociodemographic Variables and Perception of Pain in Relationship With the Difference in Prevalence of Psychiatric Disorders in the CLBP Compared With CG Subjects CLBP/CG MDEL Age Education Males Low income married Sensorial D. Affective D. Evaluative D. VAS pain Tolerance SSAS
DD
SR
AWOP
AWP
Coef
χ
Coef
χ
Coef
χ
Coef
χ
Coef
χ2
0.33 0.17 0.86 0.05 0.04 0.26 0.26 0.26 0.29 0.17 0.23
5.76** 0.77 2.29 0.21 0.30 3.80* 3.77 3.72 4.50* 0.91 1.82
0.53 0.31 0.11 0.21 0.08 0.59 0.52 0.53 0.61 0.29 0.45
3.73 0.75 3.83* 2.93 1.43 4.80* 3.83* 3.84* 5.20* 0.82 2.05
0.29 −0.44 0.04 0.10 0.02 0.24 0.29 0.27 0.28 0.15 0.26
1.81 1.97 0.58 0.65 0.07 1.30 1.94 1.62 1.70 0.31 1.09
0.67 −0.11 0.13 0.09 0.04 0.58 0.61 0.51 0.68 0.26 0.38
6.31** 0.10 5.25* 0.50 1.33 4.74* 5.27* 3.61 6.41** 0.71 1.60
0.88 0.38 0.11 0.16 0.05 0.80 0.76 0.66 0.86 0.59 0.56
6.60** 0.76 4.29* 1.65 0.59 5.57** 5.05* 3.77 6.40** 2.18 2.16
2
2
2
2
D indicates dimension of pain. *Logistic regression analysis: p < 0.05. **Logistic regression analysis: p < 0.01. ***Logistic regression analysis: p < 0.001.
hand, found that ID, along with AC, is more prevalent in the CG, whereas CLBP subjects were more likely to be classed as DYS (Table 4). However, like Rusu and Hasenbring (2008), we found a greater association between anxiety disorder and DYS pain coping style in the CLBP group, as compared with the CG (Table 8). Our results also show a greater prevalence of agoraphobia with panic disorder in the DYS cluster of CLBP patients than in their CG counterparts (Table 8), which could contribute to the lower general activity level (in particular away from home) seen in CLBP than in CG (Table 4). A greater prevalence of men and a lower income characterized the ID CLBP cluster, as compared with CG patients with the same pain coping style (Table 8). Differences were also found for the AC coping style cluster, as those from the CLBP group were predominantly married, unlike those in the CG, who were mostly single (Table 8).
DISCUSSION AND CONCLUSIONS Patients treated at a tertiary pain clinic typically have a long history of therapeutic failures and may experience a greater number of psychiatric comorbidities compared with those who turn to secondary care. This consideration is confirmed by our results, which, in fact, show a far higher prevalence of psychiatric comorbidities than some previous
studies (Mayr et al., 2003; Reme et al., 2011). In our investigation, individuals with CLBP had a prevalence of current and lifetime psychiatric disorders of approximately 74%, as compared with the 38% reported in a study of subjects sick-listed for unspecific LBP in secondary care (Reme et al., 2011). The presence of lesions that justify pain is another factor that affects the prevalence of psychiatric comorbidity (Magni and Merskey, 1987). However, our CLBP patients referred experiencing persistent pain, even after anesthetic and invasive analgesic procedures, that resisted all types of analgesic drug treatment. As their persistent pain could not be explained by lesion worsening or other complications, it may be that the very high prevalence of psychiatric disorders played a role in their suffering. That being said, there was no difference between our CLBP and CG subjects in the global prevalence of psychiatric disorders, but there were differences between the two groups in the prevalence of some specific psychiatric disorders. Indeed, CLBP was associated with a higher prevalence of MDEL, DD, SR, AWOP, and AWP with respect to CG (Table 5). This difference affected the perception of pain and was also linked to the sociodemographic characteristics of each group. A higher prevalence of MDEL in such subjects has been shown before (Licciardone et al., 2012), but we also show that the prevalence of MDEL, AWOP, and AWP in CLBP increases with increasing age,
TABLE 7. Influence of the Presence of Psychiatric Disorders in the Perception of Pain in CLBP and CG Subjects Distinguished on the Basis of Sex MDEL Sensorial CLBP CG
Affective
Evaluative
DD
AWOP
Evaluative
VAS
M
F
t
M
F
t
M
F
t
M
F
t
M
F
t
0.38 0.29
0.42 0.38
1.26 3.36***
0.42 0.31
0.44 0.43
0.66 3.19**
0.50 0.30
0.49 0.42
0.29 2.78**
0.39 0.43
0.54 0.44
2.24* 0.07
8.91 7.00
7.66 7.82
2.13* 0.67
*Logistic regression analysis: p < 0.05. **Logistic regression analysis: p < 0.01. ***Logistic regression analysis: p < 0.001.
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TABLE 8. Sociodemographic Characteristics and Psychiatric Disorders Differences in the CLBP and CG Subjects Distinguished on the Basis of MPI Coping Style AC (n = 162) Total Sex Males Females Marital status Married Divorced Single Widower Social status High Medium Low MDEL DD SR AWOP AWP
CLBP
CG
92 (56.7)
70 (43.2)
43 (46.7) 49 (53.2)
25 (35.7) 45 (64.2)
78 (84.7) 5 (5.4) 3 (3.2) 6 (6.5)
41 (58.5) 4 (5.7) 24 (34.2) 1 (1.4)
2 (1.2) 78 (48.1) 12 (7.4) 37 (22.8) 6 (3.7) 9 (5.5) 4 (2.4) 1 (0.6)
2 (1.2) 62 (38.2) 6 (3.7) 23 (14.1) 3 (1.8) 5 (3.0) 5 (3.0) 3 (1.8)
DYS (n = 124) χ2
ID (n = 191) χ2
CLBP
CG
81 (65.3)
43 (34.6)
1.98
24 (29.6) 57 (70.3)
9 (20.9) 34 (70.0)
14.15**
51 (41.1) 9 (7.2) 9 (7.2) 12 (9.6)
25 (20.1) 6 (4.8) 7 (5.6) 5 (4.0)
0.26 0.77 0.34 0.70 0.60 1.69
6 (4.8) 51 (41.1) 24 (19.3) 51 (41.1) 9 (7.2) 15 (12.0) 19 (15.3) 16 (12.9)
2 (1.6) 32 (25.8) 9 (7.2) 23 (18.5) 2 (1.6) 6 (4.8) 7 (5.6) 3 (2.4)
χ2
CLBP
CG
108 (56.5)
83 (43.4)
1.08
40 (37.0) 68 (62.9)
20 (24.0) 63 (75.9)
3.64*
0.79
52 (27.2) 16 (8.3) 25 (13.0) 15 (7.8)
49 (25.6) 6 (3.1) 23 (12.0) 5 (2.6)
2.96
0.86 1.42 1.54 1.30 1.00 3.74*
6 (3.1) 67 (35.0) 35 (18.3) 49 (25.6) 13 (6.80) 8 (4.1) 4 (2.0) 4 (2.0)
2 (1.0) 72 (37.6) 9 (4.7) 39 (20.4) 5 (2.6) 11 (5.7) 5 (2.6) 2 (1.0)
6.70* 0.04 2.07 1.18 0.52 0.29
Data are presented as n (%). *p < 0.05. **p < 0.01.
much more so than in other forms of chronic pain (Table 6). Our data therefore highlight an increased risk of depressive episodes and agoraphobia with advancing age in CLBP, but not in CG. As illustrated in Table 1, this risk is not related to the persistence of pain, as no evident differences were seen between the two groups in the time since pain onset. Sex, however, does appear to play a role, and there was a greater susceptibility of CLBP men to dysthymia, AWOP, and AWP with respect to CG men (Table 6). Our results show that the presence of MDEL and AWOP changes the perception of pain in men differently between the two groups. Indeed, as shown in the Table 7, men in the CLBP group, but not in the CG, show an increase in dimensions of pain in the presence of MDEL, and a greater pain intensity of pain in the presence of AWOP. Although previous research has found a relationship between psychosocial and sex in the perception of pain (Racine et al., 2012), evidence is still scarce on the whole. We, however, show that MDEL and AWOP do exert an influence on pain perception in male CLBP subjects. We also show an important difference between groups in the prevalence of SR, which was more closely associated with CLBP (Table 5). The association between SR and psychopathology has been studied before in CLBP patients with comorbid current depression (Cheatle, 2014). However, we found no differences in the perception of pain in the presence of SR (Table 6). Using the DCPR criteria to investigate psychosomatic dimensions revealed no differences between the two groups, with the exception of somatic amplification (SSAS), which was higher in CG patients (Table 3). Like Reme et al. (2011), we found a high rate of SPD (the third most frequent in our study) in CLBP patients, but they did not differ in this respect from CG patients (Table 5). This lack of difference in the tendency to somatize between the two groups was confirmed by the similar prevalence of somatoform disorders, as 638
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investigated by the MINI plus (Table 5). This allows us to conclude that the tendency to somatization is a general phenomenon, rather than being associated with a particular form of chronic pain. Nevertheless, considering the difference in the SSAS values seen, it is possible that a subset of the CG could explain the greater presence of somatization by increasing the SSAS scores. Sensorial encoding in the two groups was very similar, as highlighted by the cold-pain perception threshold (Table 3). However, slight differences between CLBP and GC subjects were seen in pain tolerance. Perception of pain was particularly different between groups in terms of clinical pain, and CLBP subjects perceived more severe pain with higher sensorial, affective, and evaluative dimensions than CG subjects did (Table 3). The groups also coped differently with pain, with CLBP patients being more likely to adopt a DYS coping style than the CG patients were (Table 4). A role in DYS and ID has been ascribed to operant conditioning (Rusu and Hasenbring, 2008), and our results suggest a disruptive relationship between CLBP subjects and their spouses characterized by higher punishing, lower solicitous, and higher distracting responses than in CG-affected relationships (Table 4). The DYS cluster was also associated with a greater prevalence of AWP in CLBP patients (Table 8). This association between a DYS coping style and agoraphobia seems to exacerbate the pain perceived and increase disability, restricting the socialization of subjects with CLBP. Indeed, our study shows a close relationship between pain intensity, presence of agoraphobia, lifetime depression, and dysfunctional coping style in CLBP that can also be affected by the age and sex of the subject. We therefore agree with a consensus group set up to promote health programs for CLBP in Mexico, which suggested that patients be offered a multimodal program to counteract inadequate pain management. Indeed, pain has severe physical, psychoaffective, and socioeconomic repercussions, not only for patients but also for their families © 2015 Wolters Kluwer Health, Inc. All rights reserved.
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The Journal of Nervous and Mental Disease • Volume 203, Number 8, August 2015
and the public health services (Guevara-López et al., 2011). Tertiary pain clinics therefore need to focus on multimodal psychological and psychiatric treatment to prevent greater disability, suffering, and SR in patients with CLBP. DISCLOSURE The authors declare no conflicts of interest. REFERENCES Airaksinen O, Brox JI, Cedraschi C, Hildebrandt J, Klaber-Moffett J, Kovacs F, Mannion AF, Reis S, Staal JB, Ursin H, Zanoli G (2006) COST B13 Working Group on Guidelines for Chronic Low Back Pain. Chapter 4. European guidelines for the management of chronic nonspecific low back pain. Eur Spine J. 15(suppl 2):S192–S300.
Psychiatric Disorders in CLBP
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