Psychometric properties of the Stress and Crisis Inventory (SCI-93) in females with fibromyalgia and chronic widespread pain
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ANNA ERICSSON, CURT NYSTRÖM, KAISA MANNERKORPI
Ericsson A, Nyström C, Mannerkorpi K. Psychometric properties of the Stress and Crisis Inventory (SCI-93) in females with fibromyalgia and chronic widespread pain. Nord J Psychiatry 2015;69:28–34. Background: Fibromyalgia (FM) and chronic widespread pain (CWP) are commonly associated with symptoms such as fatigue, stiffness, tension, exhaustion and psychological distress. Research on biological markers of the degree of stress symptoms has been conducted for decades. However, biological markers do not offer sufficient information for clinical practice, and thus, validated rating scales are still the best assessment option. The Stress and Crisis Inventory-93 (SCI-93) was designed to assess the severity of symptoms that are primarily related to the autonomous nervous system. Objective: The purpose of this study was to evaluate the psychometric properties of the SCI-93 with regard to known-group validity, internal consistency and test–retest reliability. Methods: The study included 166 women with FM or CWP in addition to 157 age-matched healthy women. The test–retest reliability was investigated in 40 women with FM. Results: A one-factor solution was chosen, which explained 53% of the total variance; Cronbach’s alpha was 0.98. The group of patients with FM and CWP showed significantly higher SCI-93 total scores than the healthy reference group (mean ⫽ 76.4 ⫾ 24.9 vs. mean ⫽ 24.9 ⫾ 21.3; P ⬍ 0.001), supporting known-group validity. In the test–retest reliability study, the intra class correlation for the SCI-93 total score was 0.95. Conclusions: The SCI-93 demonstrated satisfactory known-group validity and test–retest reliability. The instrument appears to reflect well the severity of autonomous symptoms. • Assessment, asthenia, burn-out, fatigue, musculoskeletal pain. Anna Ericsson, Institute of Medicine, Department of Rheumatology and Inflammation Research, Sahlgrenska Academy, University of Gothenburg, Sweden. E-mail: [email protected]; Accepted 11 April 2014.
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ibromyalgia (FM) and chronic widespread pain (CWP) are common disorders in primary healthcare. In Western countries, the prevalence is estimated to be 1–3% for FM and 7–13% for CWP (1, 2). The prevalence of FM increases with age and is higher among females (1–3). FM and CWP are characterized by widespread pain and tenderness. The hyperalgesia and allodynia observed in FM and CWP have been found to result from an increased sensitivity of central nervous mechanisms, which is referred to as sensitization (4). Dysfunction of the hypothalamic–pituitary–adrenal (HPA) axis, which coordinates the body’s physiological responses to physical and emotional stress, has also been suggested to play a role in the maintenance of widespread pain (5, 6). In addition, low-grade inflammation in FM is thought to contribute to the symptoms (6). Activation of microglia
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in the central nervous system corresponds to an inflammatory reaction, which might explain these hypotheses in an integrated manner (7). FM and CWP are associated with fatigue, sleep disturbances, stiffness, psychological distress and cognitive difficulties (1, 3, 8, 9). Associated symptoms generally make the patient approach the healthcare system (10). Patients with FM have a limited physical capacity, which leads to exhaustion and increases their levels of stress. Increased stress has been reported by women with FM to be one of the main restrictions to their ability to work (11). Long-standing exposure to stress may activate stress responses, and over time overload the organism, which furthermore may initiate compensatory psychological changes in order to maintain stability. Dysfunctional biological and psychological changes may eventually turn DOI: 10.3109/08039488.2014.915580
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out to represent an allostatic load that negatively impacts the individual’s health and resources for recovery (12). For two decades, the Stress and Crisis Inventory (SCI-93) has been used as a self-administered questionnaire based on crisis models and the impact of trauma on self-reporting (13). The SCI-93 was designed to assess the clinical manifestations of stress symptoms related to the autonomous nervous system. Research has been conducted on biomarkers to estimate the degree of deregulation of stress levels, but to date, studies have not provided sufficient information to be of help in clinical practice (5, 4, 14, 15). Validated rating scales remain the best option. The SCI-93 has been administered to patients with FM and CWP at several primary healthcare centres and rehabilitation clinics in Sweden for two decades. The instrument has been used in studies of patients with chronic pain and has been shown to be sensitive for detecting long-term improvement of symptom severity after exercise (16). However, the psychometric properties of the SCI-93 have not yet been tested in patients with FM and CWP. The absence of a more comprehensive validation motivated this study. We hypothesized that the patient group would show significantly higher scores than the healthy reference group. The two groups were used to explore the knowngroup validity, defined as the degree to which an instrument can demonstrate different scores for groups expected to vary on the variables being measured (17). Internal consistency refers to the extent to which the items in a multi-item scale are interrelated. If a patient is in stable condition, an instrument should yield reproducible scores in repeated assessments. The stability of an instrument is typically assessed by investigating test– retest reliability.
Aims To investigate the psychometric properties of the SCI-93 in females, with regard to known-group validity, internal consistency and test–retest reliability.
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on the left side of the body, pain on the right side of the body, pain above the waist, pain below the waist and axial skeletal pain, for at least 3 months and pain in 11 of 18 tender points upon digital palpation. Patients who had experienced widespread pain for at least 3 months but did not fulfil the tender point criteria were classified as having CWP (3). The exclusion criteria for the patient group and the healthy reference group were as follows: patients of treatment in progress, pregnancy, limited understanding of Swedish and severe psychiatric or somatic disorders.
Participants PATIENT GROUP The patients were recruited from primary healthcare centres in western Sweden to participate in an intervention study (16). A total of 298 potentially eligible individuals with a diagnosis related to pain were identified by searching patient records for diagnoses of FM, CWP and nonspecific pain. These individuals were contacted by mail (n ⫽ 55) or telephone (n ⫽ 243) for further screening. Forty-eight individuals could not be reached, 35 did not meet the inclusion criteria and 61 declined, whereas 154 consented to participate in the clinical examination. Twentytwo of the examined patients did not meet the inclusion criteria, and 12 were excluded due to treatment in progress (n ⫽ 3) or severe disorders (n ⫽ 9). Eighteen individuals declined to participate. Finally, 102 patients were referred to the intervention study, but one patient was excluded for not fulfilling the inclusion criteria, resulting in a total of 101 patients. At the same time, 93 individuals were consecutively recruited to the study; 65 of them fulfilled the criteria and agreed to participate in the study. The study population therefore comprised 166 patients, 134 of whom fulfilled the criteria for FM and 32 of whom fulfilled the criteria for CWP. The mean age (⫾ standard deviation) of the patient group was 46 ⫾ 8.8 years (range: 22–60 years). There were no significant differences between the two recruitment samples in age or SCI-93 total score. Fiftythree of the patients with FM and CWP in the patient group completed the SCI-93 on two occasions, 5 days apart, to investigate the test–retest reliability.
Materials and methods Design The study was cross-sectional and comparative, and also partially prospective when exploring the test–retest reliability.
Procedures The inclusion criteria for the patient group were as follows: female patients, 18–60 years of age, and a FM or CWP diagnoses according to the American College of Rheumatology criteria for FM (3). FM was diagnosed in patients who had a history of widespread pain, i.e. pain NORD J PSYCHIATRY·VOL 69 NO 1·2015
HEALTHY REFERENCE GROUP A total of 183 women between 21 and 60 years of age were recruited from a mammography screening centre (n ⫽ 77) and among employees in the public sector (n ⫽ 106). Fifteen women were excluded due to pregnancy (n ⫽ 2) or severe psychiatric or somatic disorders (n ⫽ 13). Eleven women, aged 21–30 years, were randomly excluded to achieve adequate age matching with the patient group. The remaining 157 individuals constituted the healthy reference group; their mean age was 45 ⫾ 9.0 years (range: 22–60 years).
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Ratings
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CHARACTERISTICS OF PATIENTS AND HEALTHY SUBJECTS Information regarding age, immigrant status, marital status, education, employment, sick leave, drugs and smoking was obtained by standardized interviews in the patient group and the healthy reference group. Duration of widespread pain and number of tender points were examined in the patient group (Table 1). STRESS AND CRISIS INVENTORY-93 (SCI-93) The SCI-93 comprises 35 items, assessing the clinical manifestations of stress on a 5-point Likert scale that ranges from 0 (“not at all”) to 4 (“very much”). The items include physical and mental sensations. The potential range of the total scores is 0 to 140; a higher score indicates more stress (13). Based on a Swedish population study (n ⫽ 1177), a total score of ⱕ 28 ⫾ 10) indicates Table 1. Demographic data for the patient group (n=166; 134 fibromyalgia, 32 chronic widespread pain) and for the healthy reference group (n=157).
Age, years, mean (s) Duration of widespread pain, years Tender points, number
Immigrant Marital status Living with adult Not living with adult Education ⱕ 9 years 10–12 years ⬎ 12 years Employment* 0% 1–49% 50–79% 0–100% Sick leave Part time Full time Disability pension Part time Full time Drugs Analgesic/NSAID Psychotropics† Current smoker
Patient group
Healthy reference group
Mean (s)
Mean (s)
P-value
46 (8.8) 10.5 (7.1) 13.5 (3.5)
45 (9.1) – –
0.596 – –
n (%)
n (%)
27 (16)
18 (11)
123 (74) 43 (26)
105 (67) 52 (33)
38 (23) 89 (54) 38 (23)
15 (10) 59 (38) 78 (50)
0.261 0.269
⬍ 0.001
⬍ 0.001 98 14 37 17
(59) (8) (22) (10)
9 (6) 5 (3) 28 (18) 114 (73) ⬍ 0.001
31 (19) 48 (29)
7 (4) 3 (2) ⬍ 0.001
29 (17) 37 (22)
3 (2) 5 (3)
118 (71) 74 (45) 47 (28)
7 (4) 5 (3) 39 (25)
⬍ 0.001 ⬍ 0.001 0.440
s, standard deviation. *Refers to percentage of full-time work, which is defined as 40 h per week. †Antidepressants, sedatives.
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normal resources for activity and work (18). The questionnaire requires approximately 2–5 min to complete.
Statistical analyses Descriptive statistics are presented as the mean, standard deviation (s) and range for continuous variables, and as a number and per cent for categorical variables. Factor analysis was used to investigate underlying factors reflected by the 35 items in the patient and healthy reference groups analysed together. Principal component analysis was used. Internal consistency was analysed in the patient group and the healthy reference group by calculating Cronbach’s alpha for a one-factor model for the 35 items. The Pearson correlation coefficient was used to calculate the item-to-total correlations of each item. For comparisons between the patient group and the healthy reference group, we used the Mann–Whitney U-test for continuous variables, Fisher’s exact test for dichotomous variables and the Mantel–Haenszel chi-square test for ordinal categorical variables. The test–retest reliability was analysed by the intraclass correlation coefficient (ICC) with a 95% confidence interval (CI) (19, 20). The Wilcoxon signed rank test was used to analyse systematic differences in the variables between test 2 and test 1. All of the tests were two-tailed and conducted at the 5% significance level. SPSS Statistics 18 was used for all statistical analyses. A maximum of 10% missing values (four items) was accepted and replaced by the mean value of the scores. In the patient group, four protocols had more than 10% missing values and were excluded; thus, the number included in the study was 162. In the healthy reference group, two protocols with more than 10% missing values were excluded, making the final number 155. In the test–retest reliability analysis, six patients (11%) did not return the inventory on the second occasion. Five protocols (9%) were excluded because the time between test 1 and test 2 was ⬍ 4 days or ⬎ 6 days. Two inventories completed on the second occasion were excluded as they had more than 10% missing values. The final number of patients participating in the test–retest reliability study was 40 (36 FM and 4 CWP).
Ethics The study was approved by the Regional Ethical Review Board in Gothenburg, Sweden. Informed verbal and written consent was obtained from all participants.
Results Factor structure An inspection of the screeplot revealed a clear break after the first component. One-component solution was chosen, with eigenvalue 18.7 and explained variance NORD J PSYCHIATRY·VOL 69 NO 1·2015
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53.3%. The correlations with the latent extracted factor ranged from 0.49 to 0.84.
A significant difference was found in the SCI-93 total score and all 35 items (P ⬍ 0.001) between the patient group (n ⫽ 162, mean 76.4 ⫾ 24.9, 95% CI 72.5–80.3) and the healthy reference group (n ⫽ 155, mean 24.9 ⫾ 21.3, 95% CI 21.5–28.3) (Table 2).
healthy reference group. The Cronbach’s alpha for the SCI-93 was 0.98. The item-to-total correlations between the 35 individual items and the SCI-93 total score ranged between 0.47 and 0.82 (P ⬍ 0.001). The highest correlation with the total score was obtained for the items “muscle exhaustion” and “reduced concentration”, and the lowest correlation was obtained for the item “cold hands/feet”. The deletion of any item did not increase the total Cronbach’s alpha of the inventory.
Internal consistency
Test–retest reliability
Analyses were conducted for the total number of protocols (n ⫽ 317) by combining the patient group and the
The final number of patients participating in the test–retest reliability study was 40. The mean interval between
Known-group validity
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Table 2. The mean and standard deviation (s) with the 95% confidence interval (CI) for the 35 items and the total score of the Stress and Crisis Inventory (SCI-93) for the patient group (n=157*) and the healthy reference group (n=155*). Patient group Item 1. Tension in jaws 2. Muscle pain 3. Muscle stiffness 4. Muscle exhaustion 5. General weariness 6. Irritability 7. Tingling sensations in the body 8. Numbness in arms/hands/legs/feet 9. Burning sensations in the body 10. Disturbed sleep 11. Irritation in the eyes 12. Dry mouth 13. Hypersensitivity to fragrances/lights/sounds 14. Weather susceptibility 15. Swelling sensations in hands/feet 16. Fumbling hands/fingers 17. Trembling hands 18. Dizziness 19. Varying loose/hard stools 20. Restlessness 21. Itching 22. Cold hands/feet 23. Cold/sweaty alternating sensations 24. Frequent micturition 25. Reduced concentration 26. Reduced memory 27. Pain in the skin when touched 28. Boiling sensations in the body 29. Reduced appetite 30. Fever sensation without fever 31. Palpitation 32. Weight over the chest/heavy breathing 33. Frequent headache 34. Reduced libido 35. Globus/sensation of lump in the throat Total score
Healthy reference group
Mean (s)
95% CI
Mean (s)
95% CI
P-value
1.9 (1.4) 3.4 (0.7) 3.1 (0.9) 3.3 (0.8) 3.2 (0.9) 2.4 (1.1) 2.0 (1.2) 2.2 (1.3) 1.8 (1.3) 2.8 (1.3) 1.8 (1.4) 1.9 (1.4) 2.3 (1.4) 2.7 (1.2) 2.6 (1.3) 2.6 (1.2) 1.4 (1.4) 1.8 (1.3) 2.3 (1.4) 2.1 (1.3) 1.4 (1.3) 2.4 (1.4) 2.3 (1.3) 2.0 (1.5) 2.6 (1.2) 2.5 (1.2) 2.4 (1.3) 1.7 (1.4) 0.7 (1.0) 2.0 (1.3) 1.5 (1.3) 1.5 (1.2) 2.6 (1.4) 2.1 (1.4) 1.4 (1.3) 76.4 (24.9)
1.6–2.1 3.3–3.5 2.9–3.2 3.2–3.4 3.1–3.4 2.2–2.5 1.8–2.2 2.0–2.4 1.6–2.0 2.6–3.0 1.6–2.0 1.6–2.1 2.0–2.5 2.5–2.9 2.4–2.8 2.4–2.8 1.2–1.6 1.6–2.0 2.1–2.6 1.9–2.3 1.2–1.7 2.2–2.7 2.1–2.5 1.8–2.2 2.4–2.7 2.3–2.6 2.2–2.6 1.5–1.9 0.6–0.9 1.8–2.2 1.3–1.7 1.3–1.7 2.3–2.8 1.9–2.4 1.2–1.6 72.5–80.3
0.7 (1.0) 1.3 (1.4) 1.4 (1.2) 1.2 (1.3) 1.4 (1.1) 1.1 (1.0) 0.5 (1.1) 0.6 (1.1) 0.3 (0.8) 1.1 (1.3) 0.7 (1.0) 0.4 (0.8) 0.6 (1.1) 0.8 (1.2) 0.7 (1.0) 0.5 (1.0) 0.3 (0.7) 0.5 (0.8) 0.8 (1.1) 0.8 (1.1) 0.5 (0.9) 1.4 (1.3) 0.8 (1.1) 0.7 (1.0) 0.6 (0.9) 0.9 (1.0) 0.3 (0.7) 0.4 (0.9) 0.1 (0.5) 0.4 (0.9) 0.5 (0.9) 0.4 (0.8) 1.0 (1.2) 0.8 (1.1) 0.4 (0.8) 24.9 (21.3)
0.6–0.9 1.1–1.6 1.2–1.6 1.0–1.4 1.3–1.6 0.9–1.2 0.4–0.7 0.4–0.8 0.2–0.4 0.9–1.3 0.5–0.8 0.3–0.6 0.5–0.8 0.6–1.0 0.6–0.9 0.4–0.7 0.2–0.4 0.4–0.7 0.7–1.0 0.6–1.0 0.3–0.6 1.2–1.6 0.6–1.0 0.5–0.8 0.5–0.8 0.8–1.1 0.2–0.4 0.2–0.5 0.1–0.2 0.2–0.5 0.4–0.7 0.3–0.5 0.8–1.1 0.6–0.9 0.2–0.5 21.5–28.3
⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001
s, standard deviation. *Nine protocols in the patient group and two protocols in the healthy reference group were excluded due to ⬎ 10% missing values. NORD J PSYCHIATRY·VOL 69 NO 1·2015
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the test and retest was 5.2 ⫾ 0.4 days (range 4–6 days). The mean total score was 75.7 ⫾ 26.9 (range 26–177) on the first occasion and 72.0 ⫾ 27.0 (range 21–117) on the second occasion. The mean difference between the test and retest scores for the 35 items ranged from ⫺ 0.43 to 0.08 (Table 3). The ICC for the SCI-93 total score was 0.95 and ranged from 0.60 to 0.95 for the 35 individual items (Table 3). A systematic difference was found for the SCI-93 total score (P ⫽ 0.003) and for three of the 35 items [irritation in the eyes (P ⬍ 0.001), swelling sensations in the hands/feet (P ⫽ 0.039) and palpitations (P ⫽ 0.039)], which indicated a lower level of stress at test 2 compared with test 1.
Discussion The SCI-93 comprises 35 items, and the present study supports a one-factor model for the questionnaire. Calculations of Cronbach’s alpha and item-to-total correlations indicate satisfactory internal consistency. The SCI-93 was also shown to discriminate between females in the patient group and the healthy reference group, supporting the questionnaire’s satisfactory known-group validity. The test–retest reliability was analysed in the present study and showed satisfactory ICC-values and low mean of differences between the two test occasions for the SCI-93 total score and the 35 items. The lowest item-to-total correlation was obtained for the item “cold hands/feet”. Reformulation of the item
Table 3. Calculations of test–retest reliability for the Stress and Crisis Inventory for 40 patients with fibromyalgia (n=36) and chronic widespread pain (n=4).
1. Tension in jaws 2. Muscle pain 3. Muscle stiffness 4. Muscle exhaustion 5. General weariness 6. Irritability 7. Tingling sensations in the body 8. Numbness in arms/hands/legs/feet 9. Burning sensations in the body 10. Disturbed sleep 11. Irritation in the eyes 12. Dry mouth 13. Hypersensitivity to fragrances/lights/sounds 14. Weather susceptibility 15. Swelling sensations in hands/feet 16. Fumbling hands/fingers 17. Trembling hands 18. Dizziness 19. Varying loose/hard stools 20. Restlessness 21. Itching 22. Cold hands/feet 23. Cold/sweaty alternating sensations 24. Frequent micturition 25. Reduced concentration 26. Reduced memory 27. Pain in the skin when touched 28. Boiling sensations in the body 29. Reduced appetite 30. Fever sensation without fever 31. Palpitation 32. Weight over the chest/heavy breathing 33. Frequent headache 34. Reduced libido 35. Globus/sensation of lump in the throat Total score
ICC (95% CI)
Difference mean (s)
0.79 (0.64–0.88) 0.78 (0.63–0.88) 0.60 (0.36–0.77) 0.68 (0.47–0.82) 0.76 (0.59–0.87) 0.75 (0.57–0.86) 0.87 (0.77–0.93) 0.75 (0.57–0.86) 0.74 (0.56–0.85) 0.82 (0.69–0.90) 0.88 (0.78–0.93) 0.83 (0.70–0.91) 0.89 (0.80–0.94) 0.82 (0.69–0.90) 0.85 (0.74–0.92) 0.79 (0.64–0.89) 0.94 (0.89–0.97) 0.85 (0.73–0.92) 0.86 (0.75–0.92) 0.80 (0.65–0.89) 0.82 (0.69–0.90) 0.78 (0.62–0.88) 0.86 (0.76–0.93) 0.87 (0.77–0.93) 0.84 (0.71–0.91) 0.90 (0.81–0.94) 0.84 (0.71–0.91) 0.85 (0.73–0.92) 0.95 (0.90–097) 0.89 (0.80–0.94) 0.86 (0.75–0.92) 0.72 (0.53–0.84) 0.88 (0.79–0.94) 0.87 (0.76–0.93) 0.83 (0.70–0.90) 0.95 (0.91–0.97)
0.08 (0.83) 0.03 (0.48) ⫺ 0.10 (0.84) ⫺ 0.13 (0.69) ⫺ 0.08 (0.92) ⫺ 0.23 (0.83) ⫺ 0.15 (0.58) ⫺ 0.08 (0.92) ⫺ 0.18 (0.90) ⫺ 0.18 (0.78) ⫺ 0.43 (0.64) ⫺ 0.18 (0.81) 0.05 (0.71) 0.00 (0.72) ⫺ 0.23 (0.66) ⫺ 0.23 (0.80) ⫺ 0.15 (0.48) ⫺ 0.23 (0.73) ⫺ 0.15 (0.77) ⫺ 0.23 (0.86) ⫺ 0.08 (0.84) ⫺ 0.10 (0.93) ⫺ 0.18 (0.71) ⫺ 0.13 (0.79) ⫺ 0.18 (0.75) 0.00 (0.64) 0.03 (0.77) 0.08 (0.77) 0.08 (0.27) ⫺ 0.03 (0.62) ⫺ 0.23 (0.66) ⫺ 0.08 (1.00) ⫺ 0.1 (0.67) ⫺ 0.1 (0.78) 0.03 (0.77) ⫺ 3.69 (8.38)
The intraclass correlation coefficient (ICC) with the 95% confidence interval (CI) and mean and standard deviation (s) of the difference (test 2 ⫺ test 1) for the SCI-93 (n ⫽ 40 patients FM and CWP). The mean time between test and retest was 5.2 days.
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into “intermittent cold hands/feet” is recommended to reflect autonomous symptoms. The SCI-93 was found to possess satisfactory test– retest reliability in patients with FM and CWP. The high ICC value for the total score indicates that the SCI-93 total score can be used for the evaluation of groups of patients, as well as individuals. The individual items also showed stability over time, with a satisfactory ICC value for 33 of 35 items (19, 20). The test–retest reliability results in the present study are in agreement with a study conducted in inpatients (n ⫽ 46) at the National Social Insurance Hospital in Sweden (21). Systematic differences were found between the first and second test occasions for the SCI total score and three individual items on the SCI. The differences indicated a slightly lower stress level on the second test occasion in the patient group, which might reflect the study procedure. On the first test occasion, the patient group completed a lengthy battery of questionnaires on different aspects of health, whereas the retests were completed at home 5 days later. The SCI-93 total score has previously been found to reflect an important and personal aspect of the experience of health (18). The small 95% CI of the SCI-93 total score in the present study indicates that the 35 items reflect a core group of autonomous symptoms that exist in patients with FM and CWP as well as in a healthy reference group. The face validity of the SCI-93 has been evaluated previously during the development of the instrument. The sensitivity to change of the SCI-93 has been documented in a study on long-term outcomes after pool exercise in women with FM (16) and in a study on physical exercise and relaxation in patients with coronary syndrome X (22). The scores of the patient group and the healthy reference group in the present study are in agreement with the results of previous studies of a general Swedish population (18). There were significant differences between the patient group and the healthy reference group in the present study in terms of sick leave, disability pension and use of medication, which was expected because work disability and pharmacological treatment are common in FM and CWP. The patient group also had a lower level of education and worked fewer hours per week than the healthy reference group, which is in line with previous studies of patient populations with pain (23, 24). The patients were recruited both consecutively and from patient records to attain a large study sample. No significant differences were found between the two recruitment samples in age or SCI-93 total score. A limitation of the present study is that 61 patients declined to participate, and thus, their levels of stress are unknown. Only females were included in the present study. Studies NORD J PSYCHIATRY·VOL 69 NO 1·2015
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on males with FM and CWP would add important gender aspects. Another limitation was the short time period between the two test occasions in the test–retest reliability analysis. However, the risk of recall bias was considered small because the patients completed a substantial number of questionnaires for the intervention study, including the SCI-93, at the first test occasion, and they were not informed about which instrument they would complete 5 days later. Information gathered by a questionnaire cannot exclude clinical interviews and examinations. In clinical practice, various sources of information should preferably be used in parallel. Symptoms of the autonomous body system often make patients consume considerable amounts of healthcare services (10). A simple, yet valid and reliable paper-and-pencil instrument is needed to assess symptom severity, and to motivate the patients in using active coping strategies to mitigate their stress responses. Further research is needed to study the impact of stress in pain disorders and whether a reduction of the stress level can diminish pain in patients with generalized pain. To conclude, the SCI-93 was found to possess satisfactory known-group validity and internal consistency. The SCI-93 total score, as well as the 35 items, showed a reasonable stability over time. The SCI-93 seems adequately to reflect the severity of the autonomous symptoms of the patients, and therefore appears suitable for use in female patients with FM and CWP. Acknowledgements—Financial support for the study was received from the R&D Council of FyrBoDal in the Västra Götaland Region, the Swedish Rheumatoid Association, the Swedish Research Council, the Health and Medical Care Executive Board of the Västra Götaland Region, the Göteborg Region Foundation for Rheumatology Research (GSFR) and ALF/LUA at Sahlgrenska University Hospital.
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
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editors. Fibromyalgia and other central pain syndromes. Philadelphia, PA: Lippincott Williams & Wilkins; 2005. Kadetoff D, Lampa J, Westman M, Andersson M, Kosek E. Evidence of central inflammation in fibromyalgia—Increased cerebrospinal fluid interleukin-8 levels. J Neuroimmunol 2012;242:33–8. Kavelaars A. 11th World Congress of Biological Psychiatry, Kyoto 2013, 23–27 June; Psychoneuroimmunology; Cytokines and immune activation in psychiatric disorders. Inflammationassociated pain and depression. Beyond activation of IDO. Mease P, Arnold L, Choy E, Clauw D, Crofford L, Glass J, et al. Fibromyalgia syndrome module at OMERACT 9: Domain construct. J Rheumatol 2009;36:2318–29. Rohrbeck J, Jordan K, Croft P. The frequency and characteristics of chronic widespread pain in general practice: A case-control study. Br J Gen Pract 2007;57:109–15. PubMed PMID: 17263927. Pubmed Central PMCID: 2034170. Epub 2007/02/01. eng. Fink P, Sorensen L, Engberg M, Holm M, Munk-Jorgensen P. Somatization in primary care. Prevalence, health care utilization, and general practitioner recognition. Psychosomatics 1999;40:330–8. PubMed PMID: 10402880. Mannerkorpi K, Gard G. Hinders for continued work among persons with fibromyalgia BMC Musculoskelet Disord 2012;13:96. Clauw D, Williams DA. Relationship between stress and pain in work-related upper extremity disorders: The hidden role of chronic multisymptom illnesses. Am J Indust Med 2002;41:370–82. Krafft B, Nyström C. High level of stress and immature defenses make for a vicious circle in chronic pain. Läkartidningen 2002;99:4040–3. PubMed PMID:12451940. Epub. Chida Y, Steptoe S. Cortisol awakening response and psychosocial factors: A systematic review and meta-analysis. Biol Psychol 2009;80:265–78. Pervanidou P, Chrousos G. Neuroendocrinologi of post-traumatic stress disorders. Prog Brain Res 2010;182:149–60. Mannerkorpi K, Nordeman L, Ericsson A, Arndorw M, GAU-Study-Group. Pool-exercise for patients with fibromyalgia or chronic widespread pain. A randomized controlled trial and subgroup analyses. J Rehabil Med 2009;41:751–60.
17. Polit DF, Tatano Beck C. Nursing research. Principles and methods, 7th edition. Philadelphia, PA: Lippincott Williams & Wilkins; 2004. 18. Kraft B, Nyström C, Nyström O, Pedersen C. Stressreaktion och välfärdsdata—en populationsstudie (in Swedish) [Stress reactions and welfare data—A population study]. Socialmedicinsk Tidskrift 2004(3):222–9. 19. Fleiss J. The design and analysis of clinical experiments. New York: John Wiley & Sons; 1986. 20. Shrout P, Fleiss J. Intraclass correlations: Uses in assessing rater reliability. Psychol Bulletin 1979;86:420–8. 21. Nyström C, Nyström O. [Estimated stress verifies autonomic dysfunction]. [Article in Swedish]. Lakartidningen 1996;93: 2583–4. 22. Tyni-Lenne R, Stryjan S, Eriksson B, Berglund M, Sylven C. Beneficial therapeutic effects of physical training and relaxation therapy in women with coronary syndrome X. Physiother Res Int 2002;7:35–43. 23. Bergman S. Psychosocial aspects of chronic widespread pain and fibromyalgia. Disabil Rehabil 2005;27:675–683. 24. White KP, Speechley M, Harth M, Ostbye T. Comparing selfreported function and work disability in 100 community cases of fibromyalgia syndrome versus controls in London, Ontario: The London Fibromyalgia Epidemiology Study. Arthritis Rheum 1999;42:76–83. Anna Ericsson, P.T., Ph.D., Institute of Medicine, Department of Rheumatology and Inflammation Research, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden, and Research Development & Education Centre Fyrbodal, Primary Health Care, Sweden. Curt Nyström, M.D., Sr Psychiatrist, Ph.D., Institute of Clinical Neuroscience, Department of Psychiatry for Affective Disorders I, University of Gothenburg, Sweden. Kaisa Mannerkorpi, P.T., Ph.D., Associate Professor, Institute of Medicine, Department of Rheumatology and Inflammation Research, Sahlgrenska Academy, University of Gothenburg, Göteborg, Sweden.
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ANNA ERICSSON, CURT NYSTRÖM, KAISA MANNERKORPI
Ericsson A, Nyström C, Mannerkorpi K. Psychometric properties of the Stress and Crisis Inventory (SCI-93) in females with fibromyalgia and chronic widespread pain. Nord J Psychiatry 2015;69:28–34. Background: Fibromyalgia (FM) and chronic widespread pain (CWP) are commonly associated with symptoms such as fatigue, stiffness, tension, exhaustion and psychological distress. Research on biological markers of the degree of stress symptoms has been conducted for decades. However, biological markers do not offer sufficient information for clinical practice, and thus, validated rating scales are still the best assessment option. The Stress and Crisis Inventory-93 (SCI-93) was designed to assess the severity of symptoms that are primarily related to the autonomous nervous system. Objective: The purpose of this study was to evaluate the psychometric properties of the SCI-93 with regard to known-group validity, internal consistency and test–retest reliability. Methods: The study included 166 women with FM or CWP in addition to 157 age-matched healthy women. The test–retest reliability was investigated in 40 women with FM. Results: A one-factor solution was chosen, which explained 53% of the total variance; Cronbach’s alpha was 0.98. The group of patients with FM and CWP showed significantly higher SCI-93 total scores than the healthy reference group (mean ⫽ 76.4 ⫾ 24.9 vs. mean ⫽ 24.9 ⫾ 21.3; P ⬍ 0.001), supporting known-group validity. In the test–retest reliability study, the intra class correlation for the SCI-93 total score was 0.95. Conclusions: The SCI-93 demonstrated satisfactory known-group validity and test–retest reliability. The instrument appears to reflect well the severity of autonomous symptoms. • Assessment, asthenia, burn-out, fatigue, musculoskeletal pain. Anna Ericsson, Institute of Medicine, Department of Rheumatology and Inflammation Research, Sahlgrenska Academy, University of Gothenburg, Sweden. E-mail: [email protected]; Accepted 11 April 2014.
F
ibromyalgia (FM) and chronic widespread pain (CWP) are common disorders in primary healthcare. In Western countries, the prevalence is estimated to be 1–3% for FM and 7–13% for CWP (1, 2). The prevalence of FM increases with age and is higher among females (1–3). FM and CWP are characterized by widespread pain and tenderness. The hyperalgesia and allodynia observed in FM and CWP have been found to result from an increased sensitivity of central nervous mechanisms, which is referred to as sensitization (4). Dysfunction of the hypothalamic–pituitary–adrenal (HPA) axis, which coordinates the body’s physiological responses to physical and emotional stress, has also been suggested to play a role in the maintenance of widespread pain (5, 6). In addition, low-grade inflammation in FM is thought to contribute to the symptoms (6). Activation of microglia
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in the central nervous system corresponds to an inflammatory reaction, which might explain these hypotheses in an integrated manner (7). FM and CWP are associated with fatigue, sleep disturbances, stiffness, psychological distress and cognitive difficulties (1, 3, 8, 9). Associated symptoms generally make the patient approach the healthcare system (10). Patients with FM have a limited physical capacity, which leads to exhaustion and increases their levels of stress. Increased stress has been reported by women with FM to be one of the main restrictions to their ability to work (11). Long-standing exposure to stress may activate stress responses, and over time overload the organism, which furthermore may initiate compensatory psychological changes in order to maintain stability. Dysfunctional biological and psychological changes may eventually turn DOI: 10.3109/08039488.2014.915580
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out to represent an allostatic load that negatively impacts the individual’s health and resources for recovery (12). For two decades, the Stress and Crisis Inventory (SCI-93) has been used as a self-administered questionnaire based on crisis models and the impact of trauma on self-reporting (13). The SCI-93 was designed to assess the clinical manifestations of stress symptoms related to the autonomous nervous system. Research has been conducted on biomarkers to estimate the degree of deregulation of stress levels, but to date, studies have not provided sufficient information to be of help in clinical practice (5, 4, 14, 15). Validated rating scales remain the best option. The SCI-93 has been administered to patients with FM and CWP at several primary healthcare centres and rehabilitation clinics in Sweden for two decades. The instrument has been used in studies of patients with chronic pain and has been shown to be sensitive for detecting long-term improvement of symptom severity after exercise (16). However, the psychometric properties of the SCI-93 have not yet been tested in patients with FM and CWP. The absence of a more comprehensive validation motivated this study. We hypothesized that the patient group would show significantly higher scores than the healthy reference group. The two groups were used to explore the knowngroup validity, defined as the degree to which an instrument can demonstrate different scores for groups expected to vary on the variables being measured (17). Internal consistency refers to the extent to which the items in a multi-item scale are interrelated. If a patient is in stable condition, an instrument should yield reproducible scores in repeated assessments. The stability of an instrument is typically assessed by investigating test– retest reliability.
Aims To investigate the psychometric properties of the SCI-93 in females, with regard to known-group validity, internal consistency and test–retest reliability.
CRISIS INVENTORY
on the left side of the body, pain on the right side of the body, pain above the waist, pain below the waist and axial skeletal pain, for at least 3 months and pain in 11 of 18 tender points upon digital palpation. Patients who had experienced widespread pain for at least 3 months but did not fulfil the tender point criteria were classified as having CWP (3). The exclusion criteria for the patient group and the healthy reference group were as follows: patients of treatment in progress, pregnancy, limited understanding of Swedish and severe psychiatric or somatic disorders.
Participants PATIENT GROUP The patients were recruited from primary healthcare centres in western Sweden to participate in an intervention study (16). A total of 298 potentially eligible individuals with a diagnosis related to pain were identified by searching patient records for diagnoses of FM, CWP and nonspecific pain. These individuals were contacted by mail (n ⫽ 55) or telephone (n ⫽ 243) for further screening. Forty-eight individuals could not be reached, 35 did not meet the inclusion criteria and 61 declined, whereas 154 consented to participate in the clinical examination. Twentytwo of the examined patients did not meet the inclusion criteria, and 12 were excluded due to treatment in progress (n ⫽ 3) or severe disorders (n ⫽ 9). Eighteen individuals declined to participate. Finally, 102 patients were referred to the intervention study, but one patient was excluded for not fulfilling the inclusion criteria, resulting in a total of 101 patients. At the same time, 93 individuals were consecutively recruited to the study; 65 of them fulfilled the criteria and agreed to participate in the study. The study population therefore comprised 166 patients, 134 of whom fulfilled the criteria for FM and 32 of whom fulfilled the criteria for CWP. The mean age (⫾ standard deviation) of the patient group was 46 ⫾ 8.8 years (range: 22–60 years). There were no significant differences between the two recruitment samples in age or SCI-93 total score. Fiftythree of the patients with FM and CWP in the patient group completed the SCI-93 on two occasions, 5 days apart, to investigate the test–retest reliability.
Materials and methods Design The study was cross-sectional and comparative, and also partially prospective when exploring the test–retest reliability.
Procedures The inclusion criteria for the patient group were as follows: female patients, 18–60 years of age, and a FM or CWP diagnoses according to the American College of Rheumatology criteria for FM (3). FM was diagnosed in patients who had a history of widespread pain, i.e. pain NORD J PSYCHIATRY·VOL 69 NO 1·2015
HEALTHY REFERENCE GROUP A total of 183 women between 21 and 60 years of age were recruited from a mammography screening centre (n ⫽ 77) and among employees in the public sector (n ⫽ 106). Fifteen women were excluded due to pregnancy (n ⫽ 2) or severe psychiatric or somatic disorders (n ⫽ 13). Eleven women, aged 21–30 years, were randomly excluded to achieve adequate age matching with the patient group. The remaining 157 individuals constituted the healthy reference group; their mean age was 45 ⫾ 9.0 years (range: 22–60 years).
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Ratings
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CHARACTERISTICS OF PATIENTS AND HEALTHY SUBJECTS Information regarding age, immigrant status, marital status, education, employment, sick leave, drugs and smoking was obtained by standardized interviews in the patient group and the healthy reference group. Duration of widespread pain and number of tender points were examined in the patient group (Table 1). STRESS AND CRISIS INVENTORY-93 (SCI-93) The SCI-93 comprises 35 items, assessing the clinical manifestations of stress on a 5-point Likert scale that ranges from 0 (“not at all”) to 4 (“very much”). The items include physical and mental sensations. The potential range of the total scores is 0 to 140; a higher score indicates more stress (13). Based on a Swedish population study (n ⫽ 1177), a total score of ⱕ 28 ⫾ 10) indicates Table 1. Demographic data for the patient group (n=166; 134 fibromyalgia, 32 chronic widespread pain) and for the healthy reference group (n=157).
Age, years, mean (s) Duration of widespread pain, years Tender points, number
Immigrant Marital status Living with adult Not living with adult Education ⱕ 9 years 10–12 years ⬎ 12 years Employment* 0% 1–49% 50–79% 0–100% Sick leave Part time Full time Disability pension Part time Full time Drugs Analgesic/NSAID Psychotropics† Current smoker
Patient group
Healthy reference group
Mean (s)
Mean (s)
P-value
46 (8.8) 10.5 (7.1) 13.5 (3.5)
45 (9.1) – –
0.596 – –
n (%)
n (%)
27 (16)
18 (11)
123 (74) 43 (26)
105 (67) 52 (33)
38 (23) 89 (54) 38 (23)
15 (10) 59 (38) 78 (50)
0.261 0.269
⬍ 0.001
⬍ 0.001 98 14 37 17
(59) (8) (22) (10)
9 (6) 5 (3) 28 (18) 114 (73) ⬍ 0.001
31 (19) 48 (29)
7 (4) 3 (2) ⬍ 0.001
29 (17) 37 (22)
3 (2) 5 (3)
118 (71) 74 (45) 47 (28)
7 (4) 5 (3) 39 (25)
⬍ 0.001 ⬍ 0.001 0.440
s, standard deviation. *Refers to percentage of full-time work, which is defined as 40 h per week. †Antidepressants, sedatives.
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normal resources for activity and work (18). The questionnaire requires approximately 2–5 min to complete.
Statistical analyses Descriptive statistics are presented as the mean, standard deviation (s) and range for continuous variables, and as a number and per cent for categorical variables. Factor analysis was used to investigate underlying factors reflected by the 35 items in the patient and healthy reference groups analysed together. Principal component analysis was used. Internal consistency was analysed in the patient group and the healthy reference group by calculating Cronbach’s alpha for a one-factor model for the 35 items. The Pearson correlation coefficient was used to calculate the item-to-total correlations of each item. For comparisons between the patient group and the healthy reference group, we used the Mann–Whitney U-test for continuous variables, Fisher’s exact test for dichotomous variables and the Mantel–Haenszel chi-square test for ordinal categorical variables. The test–retest reliability was analysed by the intraclass correlation coefficient (ICC) with a 95% confidence interval (CI) (19, 20). The Wilcoxon signed rank test was used to analyse systematic differences in the variables between test 2 and test 1. All of the tests were two-tailed and conducted at the 5% significance level. SPSS Statistics 18 was used for all statistical analyses. A maximum of 10% missing values (four items) was accepted and replaced by the mean value of the scores. In the patient group, four protocols had more than 10% missing values and were excluded; thus, the number included in the study was 162. In the healthy reference group, two protocols with more than 10% missing values were excluded, making the final number 155. In the test–retest reliability analysis, six patients (11%) did not return the inventory on the second occasion. Five protocols (9%) were excluded because the time between test 1 and test 2 was ⬍ 4 days or ⬎ 6 days. Two inventories completed on the second occasion were excluded as they had more than 10% missing values. The final number of patients participating in the test–retest reliability study was 40 (36 FM and 4 CWP).
Ethics The study was approved by the Regional Ethical Review Board in Gothenburg, Sweden. Informed verbal and written consent was obtained from all participants.
Results Factor structure An inspection of the screeplot revealed a clear break after the first component. One-component solution was chosen, with eigenvalue 18.7 and explained variance NORD J PSYCHIATRY·VOL 69 NO 1·2015
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53.3%. The correlations with the latent extracted factor ranged from 0.49 to 0.84.
A significant difference was found in the SCI-93 total score and all 35 items (P ⬍ 0.001) between the patient group (n ⫽ 162, mean 76.4 ⫾ 24.9, 95% CI 72.5–80.3) and the healthy reference group (n ⫽ 155, mean 24.9 ⫾ 21.3, 95% CI 21.5–28.3) (Table 2).
healthy reference group. The Cronbach’s alpha for the SCI-93 was 0.98. The item-to-total correlations between the 35 individual items and the SCI-93 total score ranged between 0.47 and 0.82 (P ⬍ 0.001). The highest correlation with the total score was obtained for the items “muscle exhaustion” and “reduced concentration”, and the lowest correlation was obtained for the item “cold hands/feet”. The deletion of any item did not increase the total Cronbach’s alpha of the inventory.
Internal consistency
Test–retest reliability
Analyses were conducted for the total number of protocols (n ⫽ 317) by combining the patient group and the
The final number of patients participating in the test–retest reliability study was 40. The mean interval between
Known-group validity
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CRISIS INVENTORY
Table 2. The mean and standard deviation (s) with the 95% confidence interval (CI) for the 35 items and the total score of the Stress and Crisis Inventory (SCI-93) for the patient group (n=157*) and the healthy reference group (n=155*). Patient group Item 1. Tension in jaws 2. Muscle pain 3. Muscle stiffness 4. Muscle exhaustion 5. General weariness 6. Irritability 7. Tingling sensations in the body 8. Numbness in arms/hands/legs/feet 9. Burning sensations in the body 10. Disturbed sleep 11. Irritation in the eyes 12. Dry mouth 13. Hypersensitivity to fragrances/lights/sounds 14. Weather susceptibility 15. Swelling sensations in hands/feet 16. Fumbling hands/fingers 17. Trembling hands 18. Dizziness 19. Varying loose/hard stools 20. Restlessness 21. Itching 22. Cold hands/feet 23. Cold/sweaty alternating sensations 24. Frequent micturition 25. Reduced concentration 26. Reduced memory 27. Pain in the skin when touched 28. Boiling sensations in the body 29. Reduced appetite 30. Fever sensation without fever 31. Palpitation 32. Weight over the chest/heavy breathing 33. Frequent headache 34. Reduced libido 35. Globus/sensation of lump in the throat Total score
Healthy reference group
Mean (s)
95% CI
Mean (s)
95% CI
P-value
1.9 (1.4) 3.4 (0.7) 3.1 (0.9) 3.3 (0.8) 3.2 (0.9) 2.4 (1.1) 2.0 (1.2) 2.2 (1.3) 1.8 (1.3) 2.8 (1.3) 1.8 (1.4) 1.9 (1.4) 2.3 (1.4) 2.7 (1.2) 2.6 (1.3) 2.6 (1.2) 1.4 (1.4) 1.8 (1.3) 2.3 (1.4) 2.1 (1.3) 1.4 (1.3) 2.4 (1.4) 2.3 (1.3) 2.0 (1.5) 2.6 (1.2) 2.5 (1.2) 2.4 (1.3) 1.7 (1.4) 0.7 (1.0) 2.0 (1.3) 1.5 (1.3) 1.5 (1.2) 2.6 (1.4) 2.1 (1.4) 1.4 (1.3) 76.4 (24.9)
1.6–2.1 3.3–3.5 2.9–3.2 3.2–3.4 3.1–3.4 2.2–2.5 1.8–2.2 2.0–2.4 1.6–2.0 2.6–3.0 1.6–2.0 1.6–2.1 2.0–2.5 2.5–2.9 2.4–2.8 2.4–2.8 1.2–1.6 1.6–2.0 2.1–2.6 1.9–2.3 1.2–1.7 2.2–2.7 2.1–2.5 1.8–2.2 2.4–2.7 2.3–2.6 2.2–2.6 1.5–1.9 0.6–0.9 1.8–2.2 1.3–1.7 1.3–1.7 2.3–2.8 1.9–2.4 1.2–1.6 72.5–80.3
0.7 (1.0) 1.3 (1.4) 1.4 (1.2) 1.2 (1.3) 1.4 (1.1) 1.1 (1.0) 0.5 (1.1) 0.6 (1.1) 0.3 (0.8) 1.1 (1.3) 0.7 (1.0) 0.4 (0.8) 0.6 (1.1) 0.8 (1.2) 0.7 (1.0) 0.5 (1.0) 0.3 (0.7) 0.5 (0.8) 0.8 (1.1) 0.8 (1.1) 0.5 (0.9) 1.4 (1.3) 0.8 (1.1) 0.7 (1.0) 0.6 (0.9) 0.9 (1.0) 0.3 (0.7) 0.4 (0.9) 0.1 (0.5) 0.4 (0.9) 0.5 (0.9) 0.4 (0.8) 1.0 (1.2) 0.8 (1.1) 0.4 (0.8) 24.9 (21.3)
0.6–0.9 1.1–1.6 1.2–1.6 1.0–1.4 1.3–1.6 0.9–1.2 0.4–0.7 0.4–0.8 0.2–0.4 0.9–1.3 0.5–0.8 0.3–0.6 0.5–0.8 0.6–1.0 0.6–0.9 0.4–0.7 0.2–0.4 0.4–0.7 0.7–1.0 0.6–1.0 0.3–0.6 1.2–1.6 0.6–1.0 0.5–0.8 0.5–0.8 0.8–1.1 0.2–0.4 0.2–0.5 0.1–0.2 0.2–0.5 0.4–0.7 0.3–0.5 0.8–1.1 0.6–0.9 0.2–0.5 21.5–28.3
⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001 ⬍ 0.001
s, standard deviation. *Nine protocols in the patient group and two protocols in the healthy reference group were excluded due to ⬎ 10% missing values. NORD J PSYCHIATRY·VOL 69 NO 1·2015
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the test and retest was 5.2 ⫾ 0.4 days (range 4–6 days). The mean total score was 75.7 ⫾ 26.9 (range 26–177) on the first occasion and 72.0 ⫾ 27.0 (range 21–117) on the second occasion. The mean difference between the test and retest scores for the 35 items ranged from ⫺ 0.43 to 0.08 (Table 3). The ICC for the SCI-93 total score was 0.95 and ranged from 0.60 to 0.95 for the 35 individual items (Table 3). A systematic difference was found for the SCI-93 total score (P ⫽ 0.003) and for three of the 35 items [irritation in the eyes (P ⬍ 0.001), swelling sensations in the hands/feet (P ⫽ 0.039) and palpitations (P ⫽ 0.039)], which indicated a lower level of stress at test 2 compared with test 1.
Discussion The SCI-93 comprises 35 items, and the present study supports a one-factor model for the questionnaire. Calculations of Cronbach’s alpha and item-to-total correlations indicate satisfactory internal consistency. The SCI-93 was also shown to discriminate between females in the patient group and the healthy reference group, supporting the questionnaire’s satisfactory known-group validity. The test–retest reliability was analysed in the present study and showed satisfactory ICC-values and low mean of differences between the two test occasions for the SCI-93 total score and the 35 items. The lowest item-to-total correlation was obtained for the item “cold hands/feet”. Reformulation of the item
Table 3. Calculations of test–retest reliability for the Stress and Crisis Inventory for 40 patients with fibromyalgia (n=36) and chronic widespread pain (n=4).
1. Tension in jaws 2. Muscle pain 3. Muscle stiffness 4. Muscle exhaustion 5. General weariness 6. Irritability 7. Tingling sensations in the body 8. Numbness in arms/hands/legs/feet 9. Burning sensations in the body 10. Disturbed sleep 11. Irritation in the eyes 12. Dry mouth 13. Hypersensitivity to fragrances/lights/sounds 14. Weather susceptibility 15. Swelling sensations in hands/feet 16. Fumbling hands/fingers 17. Trembling hands 18. Dizziness 19. Varying loose/hard stools 20. Restlessness 21. Itching 22. Cold hands/feet 23. Cold/sweaty alternating sensations 24. Frequent micturition 25. Reduced concentration 26. Reduced memory 27. Pain in the skin when touched 28. Boiling sensations in the body 29. Reduced appetite 30. Fever sensation without fever 31. Palpitation 32. Weight over the chest/heavy breathing 33. Frequent headache 34. Reduced libido 35. Globus/sensation of lump in the throat Total score
ICC (95% CI)
Difference mean (s)
0.79 (0.64–0.88) 0.78 (0.63–0.88) 0.60 (0.36–0.77) 0.68 (0.47–0.82) 0.76 (0.59–0.87) 0.75 (0.57–0.86) 0.87 (0.77–0.93) 0.75 (0.57–0.86) 0.74 (0.56–0.85) 0.82 (0.69–0.90) 0.88 (0.78–0.93) 0.83 (0.70–0.91) 0.89 (0.80–0.94) 0.82 (0.69–0.90) 0.85 (0.74–0.92) 0.79 (0.64–0.89) 0.94 (0.89–0.97) 0.85 (0.73–0.92) 0.86 (0.75–0.92) 0.80 (0.65–0.89) 0.82 (0.69–0.90) 0.78 (0.62–0.88) 0.86 (0.76–0.93) 0.87 (0.77–0.93) 0.84 (0.71–0.91) 0.90 (0.81–0.94) 0.84 (0.71–0.91) 0.85 (0.73–0.92) 0.95 (0.90–097) 0.89 (0.80–0.94) 0.86 (0.75–0.92) 0.72 (0.53–0.84) 0.88 (0.79–0.94) 0.87 (0.76–0.93) 0.83 (0.70–0.90) 0.95 (0.91–0.97)
0.08 (0.83) 0.03 (0.48) ⫺ 0.10 (0.84) ⫺ 0.13 (0.69) ⫺ 0.08 (0.92) ⫺ 0.23 (0.83) ⫺ 0.15 (0.58) ⫺ 0.08 (0.92) ⫺ 0.18 (0.90) ⫺ 0.18 (0.78) ⫺ 0.43 (0.64) ⫺ 0.18 (0.81) 0.05 (0.71) 0.00 (0.72) ⫺ 0.23 (0.66) ⫺ 0.23 (0.80) ⫺ 0.15 (0.48) ⫺ 0.23 (0.73) ⫺ 0.15 (0.77) ⫺ 0.23 (0.86) ⫺ 0.08 (0.84) ⫺ 0.10 (0.93) ⫺ 0.18 (0.71) ⫺ 0.13 (0.79) ⫺ 0.18 (0.75) 0.00 (0.64) 0.03 (0.77) 0.08 (0.77) 0.08 (0.27) ⫺ 0.03 (0.62) ⫺ 0.23 (0.66) ⫺ 0.08 (1.00) ⫺ 0.1 (0.67) ⫺ 0.1 (0.78) 0.03 (0.77) ⫺ 3.69 (8.38)
The intraclass correlation coefficient (ICC) with the 95% confidence interval (CI) and mean and standard deviation (s) of the difference (test 2 ⫺ test 1) for the SCI-93 (n ⫽ 40 patients FM and CWP). The mean time between test and retest was 5.2 days.
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into “intermittent cold hands/feet” is recommended to reflect autonomous symptoms. The SCI-93 was found to possess satisfactory test– retest reliability in patients with FM and CWP. The high ICC value for the total score indicates that the SCI-93 total score can be used for the evaluation of groups of patients, as well as individuals. The individual items also showed stability over time, with a satisfactory ICC value for 33 of 35 items (19, 20). The test–retest reliability results in the present study are in agreement with a study conducted in inpatients (n ⫽ 46) at the National Social Insurance Hospital in Sweden (21). Systematic differences were found between the first and second test occasions for the SCI total score and three individual items on the SCI. The differences indicated a slightly lower stress level on the second test occasion in the patient group, which might reflect the study procedure. On the first test occasion, the patient group completed a lengthy battery of questionnaires on different aspects of health, whereas the retests were completed at home 5 days later. The SCI-93 total score has previously been found to reflect an important and personal aspect of the experience of health (18). The small 95% CI of the SCI-93 total score in the present study indicates that the 35 items reflect a core group of autonomous symptoms that exist in patients with FM and CWP as well as in a healthy reference group. The face validity of the SCI-93 has been evaluated previously during the development of the instrument. The sensitivity to change of the SCI-93 has been documented in a study on long-term outcomes after pool exercise in women with FM (16) and in a study on physical exercise and relaxation in patients with coronary syndrome X (22). The scores of the patient group and the healthy reference group in the present study are in agreement with the results of previous studies of a general Swedish population (18). There were significant differences between the patient group and the healthy reference group in the present study in terms of sick leave, disability pension and use of medication, which was expected because work disability and pharmacological treatment are common in FM and CWP. The patient group also had a lower level of education and worked fewer hours per week than the healthy reference group, which is in line with previous studies of patient populations with pain (23, 24). The patients were recruited both consecutively and from patient records to attain a large study sample. No significant differences were found between the two recruitment samples in age or SCI-93 total score. A limitation of the present study is that 61 patients declined to participate, and thus, their levels of stress are unknown. Only females were included in the present study. Studies NORD J PSYCHIATRY·VOL 69 NO 1·2015
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on males with FM and CWP would add important gender aspects. Another limitation was the short time period between the two test occasions in the test–retest reliability analysis. However, the risk of recall bias was considered small because the patients completed a substantial number of questionnaires for the intervention study, including the SCI-93, at the first test occasion, and they were not informed about which instrument they would complete 5 days later. Information gathered by a questionnaire cannot exclude clinical interviews and examinations. In clinical practice, various sources of information should preferably be used in parallel. Symptoms of the autonomous body system often make patients consume considerable amounts of healthcare services (10). A simple, yet valid and reliable paper-and-pencil instrument is needed to assess symptom severity, and to motivate the patients in using active coping strategies to mitigate their stress responses. Further research is needed to study the impact of stress in pain disorders and whether a reduction of the stress level can diminish pain in patients with generalized pain. To conclude, the SCI-93 was found to possess satisfactory known-group validity and internal consistency. The SCI-93 total score, as well as the 35 items, showed a reasonable stability over time. The SCI-93 seems adequately to reflect the severity of the autonomous symptoms of the patients, and therefore appears suitable for use in female patients with FM and CWP. Acknowledgements—Financial support for the study was received from the R&D Council of FyrBoDal in the Västra Götaland Region, the Swedish Rheumatoid Association, the Swedish Research Council, the Health and Medical Care Executive Board of the Västra Götaland Region, the Göteborg Region Foundation for Rheumatology Research (GSFR) and ALF/LUA at Sahlgrenska University Hospital.
Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.
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