ORIGINAL ARTICLE
Validity and Reliability of Turkish Translation of Neuropathic Pain Impact on Quality-of-Life (NePIQoL) Questionnaire Betul Acar, MD*; Yakup Turkel, MD*; Orhan M. Kocak, MD†; A. Kemal Erdemoglu, MD‡ *Department of Neurology, Faculty of Medicine, Kirikkale University, Kirikkale; †Department of Psychiatry, Faculty of Medicine, Kirikkale University, Kirikkale; ‡Department of Neurology, Acibadem Hospital, Ankara, Turkey
& Abstract Objectives: The aim of this study was to adapt the “Neuropathic Pain Impact on Quality-of-Life Questionnaire” (NePIQoL) into Turkish and to test its validity and reliability in neuropathic pain patients. Methods: We enrolled 200 chronic pain patients who admitted to the Neurology Department of Kirikkale University, Faculty of Medicine, in our study. Patients were diagnosed with neuropathic or nociceptive pain based on medical history, physical examination, electromyography and nerve conduction studies, laboratory examinations, and imaging techniques. Discriminant analysis was used to diagnose the neuropathic pain regarding sensitivity and specificity. The original version of the NePIQoL was translated into Turkish by standard procedures. Results: Total NePIQoL scores were statistically different between neuropathic and nociceptive pain patients in both the first and second NePIQoL applications (P < 0.001). Cronbach’s alpha coefficient of total 12 items of the first and second applications was 0.95. These results suggest a high validity level for the Turkish version of the NePIQoL.
Address correspondence and reprint requests to: Yakup Turkel, MD, Kirikkale University, Faculty of Medicine, Department of Neurology, Kirikkale, Turkey. E-mail: [email protected]. Submitted: November 21, 2014; Revision accepted: May 11, 2015 DOI. 10.1111/papr.12330
© 2015 World Institute of Pain, 1530-7085/15/$15.00 Pain Practice, Volume , Issue , 2015 –
Conclusions: The Turkish version of NePIQoL appears to be reliable and valid for neuropathic pain impact on quality of life in patients with neuropathic pain. & Key Words: Neuropathic Pain Impact on Quality-of-Life Questionnaire, NePIQoL, neuropathic pain, nociceptive pain, reliability, quality of life, validity, Turkish
INTRODUCTION Treede and colleagues defined neuropathic pain as directly environmental without the stimulation of nociceptors or pain occurring due to dysfunction of central nervous system, in other words pain that occurs following a disease affecting the somatosensory system.1 Pain has several unfavorable effects on an individual’s life, and it is important to measure it by means of a common language in order to evaluate the pain itself as well as the effectiveness of pain-resolving methods that are in use. Therefore, the initial and most important step in pain management is to assess the pain. The fact that pain is a subjective aspect that varies from individual to individual makes it difficult to obtain an objective measurement. The basis of this measurement relies on believing the pain severity reported by the patient. Measurement of pain severity is usually based on the individual’s past experiences. The assessment should be made considering the intellectual level of the patient.2,3
2
ACAR ET AL.
Quality of life is defined as an individual’s perception of his/her position in life regarding his/her goals, expectations, standards, and interests within the context of the culture and value systems in which he/she lives. It is a broad concept which may be used as overall wellbeing including happiness and life satisfaction, influenced by one’s physical health, psychological status, beliefs, social interactions, and interactions with the environment. Quality-of-life scales are used to identify a patient’s specific needs, specify his/her psychosocial status, monitor the improvements in his/her condition, and determine the treatment approach. The methods of measuring quality of life should meet the criteria of reliability, validity, and sensitivity.4–6 The “Neuropathic Pain Impact on Quality-of-Life Questionnaire” (NePIQoL) was developed by Poole and colleagues7 to assess the impact of neuropathic pain on quality of life. To the best of our knowledge, a validity and reliability study has not been conducted for the Turkish version of this questionnaire. We therefore aimed to establish the validity and reliability of the Turkish version of NePIQoL for the assessment of neuropathic pain impact on quality of life.
METHODS Ethical approval for this study was provided by the Ethical Committee of Kirikkale University. Preparation of the Form in Turkish This study was performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. The trial followed the Good Clinical Practice guidelines. Permission to use the NePIQoL questionnaire was obtained from the author who developed the original scale. The study team translated the scale from the original English version to Turkish (forward translation). The form in Turkish was applied to the patients included in this study. Study Group A total of 200 patients (133 women and 67 men, age range: 20 to 80) with persistent pain for at least 3 months who admitted to the Neurology Clinic of Kirikkale University, Faculty of Medicine, from May 2013 to December 2013 were included in the study. The patients were grouped as nociceptive and neuropathic pain based
on medical history, neurological examination, detailed pain questionnaire (DN4), electrophysiological investigation, and neuroimaging findings. NePIQoL Questionnaire The questionnaire consists of 42 items, which are stratified in 6 subscales under the following titles: symptoms (8 items), relationship (5 items), psychological (8 items), social activity (8 items), physical (7 items), and personal care (6 items). The result of the Neuropathic Pain Impact on Quality-of-Life Questionnaire is calculated by the sum of the scores of these 42 items. The total score ranges from 42 to 210. Scores range from 1 to 5 for each item. Application of the Questionnaire To determine the characteristics of the patient’s pain, the Turkish version of the NePIQoL questionnaire was applied to the patients by a physician unaware of the patient’s previous diagnosis. The patients completed the form themselves in hospital setting without assistance. The patients were scheduled for a visit 2 to 7 days later, and completed the NePIQoL questionnaire once again. During the duration of this test–retest application, subjects received no treatment for their pain. Total scores with a range from 42 to 210 were calculated for the subjects who completed the questionnaire without assistance. Additional Measurements DN4. This is a questionnaire developed by the French Neuropathic Pain Group and combines the signs and symptoms associated with neuropathic pain. It evaluates neuropathic pain by 4 questions. The first 2 questions are based on interviewing the patient, while the other 2 are based on clinical examination. The first question defines the pain characteristics (burning, painful cold, electric shocks). The second question interrogates the paresthesia and dysesthesia in the affected area (tingling, pins and needles, numbness, itching). The third question interrogates the sensory deficit by means of examination of the affected area (hypoesthesia to touch, hypoesthesia to prick). The fourth question interrogates whether brushing causes pain or increased pain (“Does the pain increase with brushing?”). The subject replied to these questions as “yes” or “no.” Each “yes” is counted as 1 point, and each “no” is counted as 0 to calculate the
Turkish NePIQoL Validity and Reliability 3
total score. The threshold value has been established as 4/10 for neuropathic pain. With the simple symptom combinations, the DN4 questionnaire is useful to distinguish somatic pain from the pain resulting from nervous system injuries, and it reflects different mechanisms in pain pathophysiology.8 SF-36. SF-36 scale is used to evaluate the quality of life. The SF-36 is a multipurpose, short-form health survey containing 36 questions. It yields an 8-scale profile of functional health and well-being, as well as psychometrically based physical and mental health summary measures and a preference-based health utility index. The scales are as follows: physical functioning (PF), role-physical (RP), bodily pain (BP), general health (GH), vitality (V), social functioning (SF), role-emotional (RE), and mental health (MH). The questionnaire items selected also represent multiple operational indicators of health, including behavioral function and dysfunction, distress and well-being, objective reports and subjective ratings, and both favorable and unfavorable self-evaluations of general health status.9 It is a convenient instrument to investigate the quality of life and well-being in disorders of physical health. Tests of the validity and the reliability of the Turkish version have been carried out by Kocyigit et al.10 Statistical Analysis For the assessment of the data obtained in this study, Student’s t-test was used for the comparison of quantitative data between the 2 groups as well as descriptive statistical methods (mean, standard deviation). Pearson’s correlation analysis was used for the correlation of variables. Correlation coefficients were calculated for interitem correlation of the same items to assess the reliability of the test–retest approach. Cronbach’s alpha values were calculated for the total questionnaire and its subscales to test the internal validity (internal consistency) of the questionnaire. Factor analysis was also applied. The rational of the factor analysis is to support the reliability of questionnaire. Because of two administrations of questionnaire, it has been expected that the observed subscale scores are highly correlated. Moreover, the subscales should be entered in the same factor for every administration. The statistical analyses of this study were conducted using Statistical Package for Social Sciences version 16.0 (SPSS Inc., Chicago, IL, USA) package program.
RESULTS The etiology of the patients’ pain is presented in Table 1. The characteristics of the patients included in this study are presented in Table 2. A total of 133 (66.5%) women and 67 men (33.5%) of 31 to 79 years of age (mean 59.4 9.79) were enrolled in the study. The patients were stratified into 2 groups, namely neuropathic pain and nociceptive pain, based on detailed medical history, neurological examination, pain interrogation, electrophysiological investigation, and neuroimaging studies. The neuropathic and nociceptive pain groups included 100 patients each. There was no difference between the groups regarding mean age or gender. Descriptive data for the NePIQoL subscales in patients with neuropathic pain are shown in Table 3. Compliance was considerably high in the first application of NePIQoL in patients with neuropathic pain (Cronbach’s alpha coefficient: 0.90). Similarly, compliance was again considerably high in the second Table 1. Etiology of Pain Neuropathic Pain n = 100
Etiology Diabetic polyneuropathy Diabetic polyneuropathy + radiculopathy Postherpetic neuralgia Stroke Multiple sclerosis Trigeminal neuralgia Idiopathic polyneuropathy Gonarthrosis Inflammatory arthritis Osteoarthritis Pain after fracture Tendinitis Coxarthrosis Other
Nociceptive Pain n = 100
67 17 4 3 2 1 4 53 13 6 17 4 6 1
2
Table 2. Characteristics of Patients with Neuropathic Pain and Nociceptive Pain
Mean age (yrs) Range Gender (Female) Gender (Male)
Total n = 200
Neuropathic Pain n = 100
Nociceptive Pain n = 100
P value
59.4 9.79
60.4 10.40
58.5 9.07
0.19
31 to 79 66.5%
31 to 79 63%
35 to 79 64%
0.54
33.5%
37%
36%
4
ACAR ET AL.
Table 3. Descriptive Data for NePIQoL Subscales in Neuropathic Pain Patients Time 1
Time 2
Subscales
Mean
SD
Range
Mean
SD
Range
Symptoms Relationship Psychological Social activity Physical Personal care
36.56 19.89 35.71 34.58 31.03 25.70
3.55 3.41 4.39 4.47 4.31 4.25
27 8 22 17 11 13
37.05 20.49 36.04 34.83 31.40 26.12
3.36 3.31 4.18 4.30 3.98 4.01
27 10 23 18 13 13
to to to to to to
40 25 40 40 35 30
to to to to to to
40 25 40 40 35 30
Table 4. Cronbach’s Alpha, and Test–retest Correlations for Each Subscale in Neuropathic Pain Patients
Subscales
Number of Items
Cronbach’s Alpha
Correlation between Time 1 and Time 2 NePIQoL (Pearson’s r*)
Symptoms Relationship Psychological Social activity Physical Personal care
8 5 8 8 7 6
0.89 0.88 0.88 0.88 0.88 0.90
0.99 0.99 0.99 0.99 0.99 0.99
*P = 0.001.
application of the questionnaire (Cronbach’s alpha coefficient: 0.89). Cronbach’s alpha coefficient of total 12 items of the first and second applications was 0.95. Cronbach’s alpha coefficients for each subscale of NePIQoL in patients with neuropathic pain are shown in Table 4. High correlations were observed between the first and second applications of each subscale of NePIQoL in patients with neuropathic pain (Table 4). The correlation between NePIQoL subscales and SF36 subscales was assessed in patients with neuropathic pain (Tables 5 and 6). All of the NePIQoL subscales showed markedly negative correlation with the physical function, pain, social function, and mental health subscales of SF-36. The NePIQoL subscales of relationship, social activity, and physical showed markedly negative correlation with physical role limitation subscale of SF-36. During the factor analysis, relationship values above 0.5 were considered as inclusion criteria for the factor. According to the factor analysis between the subscales of NePIQoL and SF-36 questionnaires, the subscales were distributed to a total of 3 factors. All of the NePIQoL subscales and physical function, pain, social function, and mental health subscales of SF-36 were in
factor one, while physical role limitation and emotional role limitation were in factor 2 and overall health and vitality were in factor 3. These 3 factors were loaded with 69.33% of the entire data (Table 7). In both groups, total scores were obtained for the subscales of NePIQoL and SF-36 questionnaires. Mean total score of NePIQoL subscales in patients with neuropathic pain was 183.47 20.06 in the first measurement and 185.93 18.88 in the second, while it was 62.48 19.18 in patients with nociceptive pain in the first measurement and 62.25 13.03 in the second, and statistically, there was a highly significant difference between the 2 groups (P = 0.001). Mean total score of SF-36 subscales in patients with neuropathic pain was 177.12 98.74 in the first measurement and 173.36 96.09 in the second, while it was 619.94 101.65 in patients with nociceptive pain in the first measurement and 630.36 98.15 in the second, and the difference between the 2 groups was statistically significant (P = 0.001).
DISCUSSION The NePIQoL questionnaire has been designed for use in clinical practice and studies to assess the strength and effects of treatment and to determine the impact of neuropathic pain on quality of life among the patients.7 In our study, we aimed to test the validity and reliability of the Turkish version of the NePIQoL questionnaire for the assessment of quality of life. The findings obtained in the present study show that the Turkish version of the NePIQoL questionnaire bears sufficient characteristics to evaluate quality of life for pain in neuropathic pain patients in Turkish population. Using the test–retest method increases the reliability to assess the quality of life. Furthermore, Cronbach’s alpha coefficient was 0.99 for each subscale of NePIQoL in patients with neuropathic pain. These findings demonstrate the high level of reliability of the Turkish version of NePIQoL. When the subscales of NePIQoL and SF-36 were included in a factor analysis altogether, all of the NePIQoL subscales and physical function, pain, social function, and mental health subscales of SF-36 were observed to be in factor one, while physical role limitation and emotional role limitation were in factor 2 and overall health and energy/vitality were in factor 3. The assessment of the subscales found in the same factor during the factor analysis and the important correlations
Turkish NePIQoL Validity and Reliability 5
Table 5. Significant Correlations (P < 0.05) between NePIQoL and SF-36 at Time 1 Scales SF-36 Physical functioning Role-physical Pain General health Vitality Social functioning Mental health Role-emotional
Symptoms
Relationship
Psychological
Social Activity
Physical
Personal Care
NePIQoL Total
0.30
0.69 0.31 0.57 0.39 0.28 0.54 0.32
0.49
0.56 0.34 0.53 0.37 0.31 0.49 0.44
0.65 0.28 0.67 0.33
0.52
0.55 0.43
0.50 0.37
0.65 0.32 0.69 0.38 0.31 0.64 0.46
0.50
0.42 0.21
0.59 0.33 0.30 0.61 0.44
0.53
Table 6. Significant Correlations (P < 0.05) between NePIQoL and SF-36 at Time 2 Scales SF-36 Physical functioning Role-physical Pain General health Vitality Social functioning Mental health Role-emotional
Symptoms
Relationship
Psychological
Social Activity
Physical
Personal Care
0.29
0.70 0.30 0.58 0.41 0.27 0.54 0.35
0.49
0.55 0.33 0.53 0.39 0.29 0.48 0.49
0.65 0.31 0.67 0.34
0.51
0.55 0.47
0.50 0.38
0.49
0.42 0.21
0.57 0.33 0.32 0.60 0.45
Table 7. The Factor Analysis of NePIQoL and SF-36 Factor Scale NePIQoL Symptoms Time 1 Relationship Time 1 Psychological Time 1 Social activity Time 1 Physical Time 1 Personal care Time 1 SF-36 Physical functioning Time 1 Role-physical Time 1 Pain Time 1 General health Time 1 Vitality Time 1 Social functioning Time 1 Mental health Time 1 Role-emotional Time 1
1
2
3
0.62 0.81 0.79 0.79 0.82 0.71 0.75 0.50 0.80 0.57
0.71 0.59 0.62
0.77 0.60 0.75
observed in the correlation analysis revealed that NePIQoL subscales rate similar conditions compared to SF-36 subscales. Because high scores on the SF-36 mean better health and high scores on the NePIQoL are indicative of greater negative impact, as shown in Table 7, the direction of the correlation coefficients of the subscales of the NePIQoL questionnaire is opposite the direction of the SF-36 subscales’ correlation coefficients which were in the same factor. These findings
0.54
NePIQoL Total 0.65 0.31 0.69 0.39 0.30 0.64 0.49
demonstrate the reliability of the Turkish version of the questionnaire. The presence of nondemonstrated correlations between the NePIQoL and SF-36 subscales may be explained by the fact that SF-36 is specific to overall quality of life while NePIQoL is specific to neuropathic pain. In contrast to the original study, patients with nociceptive pain were also assessed in the present study. In both groups, total scores were obtained and compared for the subscales of the NePIQoL and SF-36 questionnaires. This resulted in showing a more unfavorably affected quality of life in patients with neuropathic pain. Smith and colleagues also compared neuropathic pain with other types of chronic pain and demonstrated a more unfavorable impact on quality of life.11 Liberman et al.12 indicated that the impact of neuropathic pain in patients with DM is much more significant than that of nociceptive pain and affects their quality of life and daily function to a greater degree. This may explain why the quality of life of neuropathic pain is worse than that of nociceptive pain. There are some limitations of the present study. First, the Turkish translation of the original questionnaire was not translated backward into English. Opinions of the field professionals about translation were collected.
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ACAR ET AL.
Accordingly, the Turkish of the questionnaire is accepted as comprehensible. Second, the scales used in the original study for pain severity and psychiatric assessments were not used in the present study. It is recommended to perform these comparisons with larger groups in future studies. In pain management, the impact of pain on quality of life is as important as identifying the pain for the patient and the clinician. In conclusion, the present study supports the validity and reliability of the Turkish version of the NePIQoL questionnaire in patients with neuropathic pain.
CONFLICT OF INTEREST The authors report no conflict of interests.
REFERENCES 1. Treede RD, Jensen TS, Campbell JN, et al. Neuropathic pain redefinition and a grading system for clinical and research purposes. Neurology. 2008;70:1630–1635. 2. International Association for the Study of Pain. Classification of chronic pain. Pain. 1986;3(suppl.):S1–S225. 3. Merskey H, Bogduk N, eds. Classification of Chronic Pain: Descriptions of Chronic Pain Syndromes and Definitions of Pain Terms, 2nd ed.. Seattle, WA: IASP Press; 1994.
€ € ßu €lmesi, WHOQOL– 4. Ozkan S. Yasßam Kalitesinin Olc 100 ve WHOQOL-BFEF. Psikiyatri, Psikoloji, Psikoformokoloji dergisi. 1999;7:5–13. 5. What quality of life? The WHOQOL Group. World Health Organization Quality of Life Assessment World Health Forum. 1996;17:354–356. 6. Pınar R. Sa glıkla ilgili yasßam kalitesi. Aylık Akt€ uel Tıp Dergisi. 1997;9:117–123. 7. Poole HM, Murphy P, Nurmikko TJ. Development and preliminary validation of the NePIQoL: a quality-of life measure for neuropathic pain. J Pain Symptom Manage. 2009;37:233–245. 8. Bouhassira D, Attal N, Alchaar H, et al. Comparison of pain syndromes associated with nervous or somatic lesions and development of a new neuropathic pain diagnostic questionnaire (DN4). Pain. 2005;114:29–36. 9. Ware JE Jr. SF-36 health survey update. Spine. 2000;25:3130–3139. € Fisek G, et al. Kısa Form10. Kocßyi git H, Aydemir O, 0 _ ß 36 nın T€ urkcße Versiyonunun G€ uvenilirli gi ve Gecßerlili gi. Ilac ve Tedavi Dergisi. 1999;12:102–106. 11. Smith BH, Torrance N, Bennett MI, Lee AJ. Health and quality of life associated with chronic pain of predominantly neuropathic origin in the community. J Pain. 2007;23:143–149. 12. Liberman O, Peleg R, Shvartzman P. Chronic pain in type 2 diabetic patients: a cross-sectional study in primary care setting. Eur J Gen Pract. 2014;20:260–267.
Validity and Reliability of Turkish Translation of Neuropathic Pain Impact on Quality-of-Life (NePIQoL) Questionnaire Betul Acar, MD*; Yakup Turkel, MD*; Orhan M. Kocak, MD†; A. Kemal Erdemoglu, MD‡ *Department of Neurology, Faculty of Medicine, Kirikkale University, Kirikkale; †Department of Psychiatry, Faculty of Medicine, Kirikkale University, Kirikkale; ‡Department of Neurology, Acibadem Hospital, Ankara, Turkey
& Abstract Objectives: The aim of this study was to adapt the “Neuropathic Pain Impact on Quality-of-Life Questionnaire” (NePIQoL) into Turkish and to test its validity and reliability in neuropathic pain patients. Methods: We enrolled 200 chronic pain patients who admitted to the Neurology Department of Kirikkale University, Faculty of Medicine, in our study. Patients were diagnosed with neuropathic or nociceptive pain based on medical history, physical examination, electromyography and nerve conduction studies, laboratory examinations, and imaging techniques. Discriminant analysis was used to diagnose the neuropathic pain regarding sensitivity and specificity. The original version of the NePIQoL was translated into Turkish by standard procedures. Results: Total NePIQoL scores were statistically different between neuropathic and nociceptive pain patients in both the first and second NePIQoL applications (P < 0.001). Cronbach’s alpha coefficient of total 12 items of the first and second applications was 0.95. These results suggest a high validity level for the Turkish version of the NePIQoL.
Address correspondence and reprint requests to: Yakup Turkel, MD, Kirikkale University, Faculty of Medicine, Department of Neurology, Kirikkale, Turkey. E-mail: [email protected]. Submitted: November 21, 2014; Revision accepted: May 11, 2015 DOI. 10.1111/papr.12330
© 2015 World Institute of Pain, 1530-7085/15/$15.00 Pain Practice, Volume , Issue , 2015 –
Conclusions: The Turkish version of NePIQoL appears to be reliable and valid for neuropathic pain impact on quality of life in patients with neuropathic pain. & Key Words: Neuropathic Pain Impact on Quality-of-Life Questionnaire, NePIQoL, neuropathic pain, nociceptive pain, reliability, quality of life, validity, Turkish
INTRODUCTION Treede and colleagues defined neuropathic pain as directly environmental without the stimulation of nociceptors or pain occurring due to dysfunction of central nervous system, in other words pain that occurs following a disease affecting the somatosensory system.1 Pain has several unfavorable effects on an individual’s life, and it is important to measure it by means of a common language in order to evaluate the pain itself as well as the effectiveness of pain-resolving methods that are in use. Therefore, the initial and most important step in pain management is to assess the pain. The fact that pain is a subjective aspect that varies from individual to individual makes it difficult to obtain an objective measurement. The basis of this measurement relies on believing the pain severity reported by the patient. Measurement of pain severity is usually based on the individual’s past experiences. The assessment should be made considering the intellectual level of the patient.2,3
2
ACAR ET AL.
Quality of life is defined as an individual’s perception of his/her position in life regarding his/her goals, expectations, standards, and interests within the context of the culture and value systems in which he/she lives. It is a broad concept which may be used as overall wellbeing including happiness and life satisfaction, influenced by one’s physical health, psychological status, beliefs, social interactions, and interactions with the environment. Quality-of-life scales are used to identify a patient’s specific needs, specify his/her psychosocial status, monitor the improvements in his/her condition, and determine the treatment approach. The methods of measuring quality of life should meet the criteria of reliability, validity, and sensitivity.4–6 The “Neuropathic Pain Impact on Quality-of-Life Questionnaire” (NePIQoL) was developed by Poole and colleagues7 to assess the impact of neuropathic pain on quality of life. To the best of our knowledge, a validity and reliability study has not been conducted for the Turkish version of this questionnaire. We therefore aimed to establish the validity and reliability of the Turkish version of NePIQoL for the assessment of neuropathic pain impact on quality of life.
METHODS Ethical approval for this study was provided by the Ethical Committee of Kirikkale University. Preparation of the Form in Turkish This study was performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. The trial followed the Good Clinical Practice guidelines. Permission to use the NePIQoL questionnaire was obtained from the author who developed the original scale. The study team translated the scale from the original English version to Turkish (forward translation). The form in Turkish was applied to the patients included in this study. Study Group A total of 200 patients (133 women and 67 men, age range: 20 to 80) with persistent pain for at least 3 months who admitted to the Neurology Clinic of Kirikkale University, Faculty of Medicine, from May 2013 to December 2013 were included in the study. The patients were grouped as nociceptive and neuropathic pain based
on medical history, neurological examination, detailed pain questionnaire (DN4), electrophysiological investigation, and neuroimaging findings. NePIQoL Questionnaire The questionnaire consists of 42 items, which are stratified in 6 subscales under the following titles: symptoms (8 items), relationship (5 items), psychological (8 items), social activity (8 items), physical (7 items), and personal care (6 items). The result of the Neuropathic Pain Impact on Quality-of-Life Questionnaire is calculated by the sum of the scores of these 42 items. The total score ranges from 42 to 210. Scores range from 1 to 5 for each item. Application of the Questionnaire To determine the characteristics of the patient’s pain, the Turkish version of the NePIQoL questionnaire was applied to the patients by a physician unaware of the patient’s previous diagnosis. The patients completed the form themselves in hospital setting without assistance. The patients were scheduled for a visit 2 to 7 days later, and completed the NePIQoL questionnaire once again. During the duration of this test–retest application, subjects received no treatment for their pain. Total scores with a range from 42 to 210 were calculated for the subjects who completed the questionnaire without assistance. Additional Measurements DN4. This is a questionnaire developed by the French Neuropathic Pain Group and combines the signs and symptoms associated with neuropathic pain. It evaluates neuropathic pain by 4 questions. The first 2 questions are based on interviewing the patient, while the other 2 are based on clinical examination. The first question defines the pain characteristics (burning, painful cold, electric shocks). The second question interrogates the paresthesia and dysesthesia in the affected area (tingling, pins and needles, numbness, itching). The third question interrogates the sensory deficit by means of examination of the affected area (hypoesthesia to touch, hypoesthesia to prick). The fourth question interrogates whether brushing causes pain or increased pain (“Does the pain increase with brushing?”). The subject replied to these questions as “yes” or “no.” Each “yes” is counted as 1 point, and each “no” is counted as 0 to calculate the
Turkish NePIQoL Validity and Reliability 3
total score. The threshold value has been established as 4/10 for neuropathic pain. With the simple symptom combinations, the DN4 questionnaire is useful to distinguish somatic pain from the pain resulting from nervous system injuries, and it reflects different mechanisms in pain pathophysiology.8 SF-36. SF-36 scale is used to evaluate the quality of life. The SF-36 is a multipurpose, short-form health survey containing 36 questions. It yields an 8-scale profile of functional health and well-being, as well as psychometrically based physical and mental health summary measures and a preference-based health utility index. The scales are as follows: physical functioning (PF), role-physical (RP), bodily pain (BP), general health (GH), vitality (V), social functioning (SF), role-emotional (RE), and mental health (MH). The questionnaire items selected also represent multiple operational indicators of health, including behavioral function and dysfunction, distress and well-being, objective reports and subjective ratings, and both favorable and unfavorable self-evaluations of general health status.9 It is a convenient instrument to investigate the quality of life and well-being in disorders of physical health. Tests of the validity and the reliability of the Turkish version have been carried out by Kocyigit et al.10 Statistical Analysis For the assessment of the data obtained in this study, Student’s t-test was used for the comparison of quantitative data between the 2 groups as well as descriptive statistical methods (mean, standard deviation). Pearson’s correlation analysis was used for the correlation of variables. Correlation coefficients were calculated for interitem correlation of the same items to assess the reliability of the test–retest approach. Cronbach’s alpha values were calculated for the total questionnaire and its subscales to test the internal validity (internal consistency) of the questionnaire. Factor analysis was also applied. The rational of the factor analysis is to support the reliability of questionnaire. Because of two administrations of questionnaire, it has been expected that the observed subscale scores are highly correlated. Moreover, the subscales should be entered in the same factor for every administration. The statistical analyses of this study were conducted using Statistical Package for Social Sciences version 16.0 (SPSS Inc., Chicago, IL, USA) package program.
RESULTS The etiology of the patients’ pain is presented in Table 1. The characteristics of the patients included in this study are presented in Table 2. A total of 133 (66.5%) women and 67 men (33.5%) of 31 to 79 years of age (mean 59.4 9.79) were enrolled in the study. The patients were stratified into 2 groups, namely neuropathic pain and nociceptive pain, based on detailed medical history, neurological examination, pain interrogation, electrophysiological investigation, and neuroimaging studies. The neuropathic and nociceptive pain groups included 100 patients each. There was no difference between the groups regarding mean age or gender. Descriptive data for the NePIQoL subscales in patients with neuropathic pain are shown in Table 3. Compliance was considerably high in the first application of NePIQoL in patients with neuropathic pain (Cronbach’s alpha coefficient: 0.90). Similarly, compliance was again considerably high in the second Table 1. Etiology of Pain Neuropathic Pain n = 100
Etiology Diabetic polyneuropathy Diabetic polyneuropathy + radiculopathy Postherpetic neuralgia Stroke Multiple sclerosis Trigeminal neuralgia Idiopathic polyneuropathy Gonarthrosis Inflammatory arthritis Osteoarthritis Pain after fracture Tendinitis Coxarthrosis Other
Nociceptive Pain n = 100
67 17 4 3 2 1 4 53 13 6 17 4 6 1
2
Table 2. Characteristics of Patients with Neuropathic Pain and Nociceptive Pain
Mean age (yrs) Range Gender (Female) Gender (Male)
Total n = 200
Neuropathic Pain n = 100
Nociceptive Pain n = 100
P value
59.4 9.79
60.4 10.40
58.5 9.07
0.19
31 to 79 66.5%
31 to 79 63%
35 to 79 64%
0.54
33.5%
37%
36%
4
ACAR ET AL.
Table 3. Descriptive Data for NePIQoL Subscales in Neuropathic Pain Patients Time 1
Time 2
Subscales
Mean
SD
Range
Mean
SD
Range
Symptoms Relationship Psychological Social activity Physical Personal care
36.56 19.89 35.71 34.58 31.03 25.70
3.55 3.41 4.39 4.47 4.31 4.25
27 8 22 17 11 13
37.05 20.49 36.04 34.83 31.40 26.12
3.36 3.31 4.18 4.30 3.98 4.01
27 10 23 18 13 13
to to to to to to
40 25 40 40 35 30
to to to to to to
40 25 40 40 35 30
Table 4. Cronbach’s Alpha, and Test–retest Correlations for Each Subscale in Neuropathic Pain Patients
Subscales
Number of Items
Cronbach’s Alpha
Correlation between Time 1 and Time 2 NePIQoL (Pearson’s r*)
Symptoms Relationship Psychological Social activity Physical Personal care
8 5 8 8 7 6
0.89 0.88 0.88 0.88 0.88 0.90
0.99 0.99 0.99 0.99 0.99 0.99
*P = 0.001.
application of the questionnaire (Cronbach’s alpha coefficient: 0.89). Cronbach’s alpha coefficient of total 12 items of the first and second applications was 0.95. Cronbach’s alpha coefficients for each subscale of NePIQoL in patients with neuropathic pain are shown in Table 4. High correlations were observed between the first and second applications of each subscale of NePIQoL in patients with neuropathic pain (Table 4). The correlation between NePIQoL subscales and SF36 subscales was assessed in patients with neuropathic pain (Tables 5 and 6). All of the NePIQoL subscales showed markedly negative correlation with the physical function, pain, social function, and mental health subscales of SF-36. The NePIQoL subscales of relationship, social activity, and physical showed markedly negative correlation with physical role limitation subscale of SF-36. During the factor analysis, relationship values above 0.5 were considered as inclusion criteria for the factor. According to the factor analysis between the subscales of NePIQoL and SF-36 questionnaires, the subscales were distributed to a total of 3 factors. All of the NePIQoL subscales and physical function, pain, social function, and mental health subscales of SF-36 were in
factor one, while physical role limitation and emotional role limitation were in factor 2 and overall health and vitality were in factor 3. These 3 factors were loaded with 69.33% of the entire data (Table 7). In both groups, total scores were obtained for the subscales of NePIQoL and SF-36 questionnaires. Mean total score of NePIQoL subscales in patients with neuropathic pain was 183.47 20.06 in the first measurement and 185.93 18.88 in the second, while it was 62.48 19.18 in patients with nociceptive pain in the first measurement and 62.25 13.03 in the second, and statistically, there was a highly significant difference between the 2 groups (P = 0.001). Mean total score of SF-36 subscales in patients with neuropathic pain was 177.12 98.74 in the first measurement and 173.36 96.09 in the second, while it was 619.94 101.65 in patients with nociceptive pain in the first measurement and 630.36 98.15 in the second, and the difference between the 2 groups was statistically significant (P = 0.001).
DISCUSSION The NePIQoL questionnaire has been designed for use in clinical practice and studies to assess the strength and effects of treatment and to determine the impact of neuropathic pain on quality of life among the patients.7 In our study, we aimed to test the validity and reliability of the Turkish version of the NePIQoL questionnaire for the assessment of quality of life. The findings obtained in the present study show that the Turkish version of the NePIQoL questionnaire bears sufficient characteristics to evaluate quality of life for pain in neuropathic pain patients in Turkish population. Using the test–retest method increases the reliability to assess the quality of life. Furthermore, Cronbach’s alpha coefficient was 0.99 for each subscale of NePIQoL in patients with neuropathic pain. These findings demonstrate the high level of reliability of the Turkish version of NePIQoL. When the subscales of NePIQoL and SF-36 were included in a factor analysis altogether, all of the NePIQoL subscales and physical function, pain, social function, and mental health subscales of SF-36 were observed to be in factor one, while physical role limitation and emotional role limitation were in factor 2 and overall health and energy/vitality were in factor 3. The assessment of the subscales found in the same factor during the factor analysis and the important correlations
Turkish NePIQoL Validity and Reliability 5
Table 5. Significant Correlations (P < 0.05) between NePIQoL and SF-36 at Time 1 Scales SF-36 Physical functioning Role-physical Pain General health Vitality Social functioning Mental health Role-emotional
Symptoms
Relationship
Psychological
Social Activity
Physical
Personal Care
NePIQoL Total
0.30
0.69 0.31 0.57 0.39 0.28 0.54 0.32
0.49
0.56 0.34 0.53 0.37 0.31 0.49 0.44
0.65 0.28 0.67 0.33
0.52
0.55 0.43
0.50 0.37
0.65 0.32 0.69 0.38 0.31 0.64 0.46
0.50
0.42 0.21
0.59 0.33 0.30 0.61 0.44
0.53
Table 6. Significant Correlations (P < 0.05) between NePIQoL and SF-36 at Time 2 Scales SF-36 Physical functioning Role-physical Pain General health Vitality Social functioning Mental health Role-emotional
Symptoms
Relationship
Psychological
Social Activity
Physical
Personal Care
0.29
0.70 0.30 0.58 0.41 0.27 0.54 0.35
0.49
0.55 0.33 0.53 0.39 0.29 0.48 0.49
0.65 0.31 0.67 0.34
0.51
0.55 0.47
0.50 0.38
0.49
0.42 0.21
0.57 0.33 0.32 0.60 0.45
Table 7. The Factor Analysis of NePIQoL and SF-36 Factor Scale NePIQoL Symptoms Time 1 Relationship Time 1 Psychological Time 1 Social activity Time 1 Physical Time 1 Personal care Time 1 SF-36 Physical functioning Time 1 Role-physical Time 1 Pain Time 1 General health Time 1 Vitality Time 1 Social functioning Time 1 Mental health Time 1 Role-emotional Time 1
1
2
3
0.62 0.81 0.79 0.79 0.82 0.71 0.75 0.50 0.80 0.57
0.71 0.59 0.62
0.77 0.60 0.75
observed in the correlation analysis revealed that NePIQoL subscales rate similar conditions compared to SF-36 subscales. Because high scores on the SF-36 mean better health and high scores on the NePIQoL are indicative of greater negative impact, as shown in Table 7, the direction of the correlation coefficients of the subscales of the NePIQoL questionnaire is opposite the direction of the SF-36 subscales’ correlation coefficients which were in the same factor. These findings
0.54
NePIQoL Total 0.65 0.31 0.69 0.39 0.30 0.64 0.49
demonstrate the reliability of the Turkish version of the questionnaire. The presence of nondemonstrated correlations between the NePIQoL and SF-36 subscales may be explained by the fact that SF-36 is specific to overall quality of life while NePIQoL is specific to neuropathic pain. In contrast to the original study, patients with nociceptive pain were also assessed in the present study. In both groups, total scores were obtained and compared for the subscales of the NePIQoL and SF-36 questionnaires. This resulted in showing a more unfavorably affected quality of life in patients with neuropathic pain. Smith and colleagues also compared neuropathic pain with other types of chronic pain and demonstrated a more unfavorable impact on quality of life.11 Liberman et al.12 indicated that the impact of neuropathic pain in patients with DM is much more significant than that of nociceptive pain and affects their quality of life and daily function to a greater degree. This may explain why the quality of life of neuropathic pain is worse than that of nociceptive pain. There are some limitations of the present study. First, the Turkish translation of the original questionnaire was not translated backward into English. Opinions of the field professionals about translation were collected.
6
ACAR ET AL.
Accordingly, the Turkish of the questionnaire is accepted as comprehensible. Second, the scales used in the original study for pain severity and psychiatric assessments were not used in the present study. It is recommended to perform these comparisons with larger groups in future studies. In pain management, the impact of pain on quality of life is as important as identifying the pain for the patient and the clinician. In conclusion, the present study supports the validity and reliability of the Turkish version of the NePIQoL questionnaire in patients with neuropathic pain.
CONFLICT OF INTEREST The authors report no conflict of interests.
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€ € ßu €lmesi, WHOQOL– 4. Ozkan S. Yasßam Kalitesinin Olc 100 ve WHOQOL-BFEF. Psikiyatri, Psikoloji, Psikoformokoloji dergisi. 1999;7:5–13. 5. What quality of life? The WHOQOL Group. World Health Organization Quality of Life Assessment World Health Forum. 1996;17:354–356. 6. Pınar R. Sa glıkla ilgili yasßam kalitesi. Aylık Akt€ uel Tıp Dergisi. 1997;9:117–123. 7. Poole HM, Murphy P, Nurmikko TJ. Development and preliminary validation of the NePIQoL: a quality-of life measure for neuropathic pain. J Pain Symptom Manage. 2009;37:233–245. 8. Bouhassira D, Attal N, Alchaar H, et al. Comparison of pain syndromes associated with nervous or somatic lesions and development of a new neuropathic pain diagnostic questionnaire (DN4). Pain. 2005;114:29–36. 9. Ware JE Jr. SF-36 health survey update. Spine. 2000;25:3130–3139. € Fisek G, et al. Kısa Form10. Kocßyi git H, Aydemir O, 0 _ ß 36 nın T€ urkcße Versiyonunun G€ uvenilirli gi ve Gecßerlili gi. Ilac ve Tedavi Dergisi. 1999;12:102–106. 11. Smith BH, Torrance N, Bennett MI, Lee AJ. Health and quality of life associated with chronic pain of predominantly neuropathic origin in the community. J Pain. 2007;23:143–149. 12. Liberman O, Peleg R, Shvartzman P. Chronic pain in type 2 diabetic patients: a cross-sectional study in primary care setting. Eur J Gen Pract. 2014;20:260–267.
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