Validity, Reliability of World Health Organization Disability Assessment Schedule 2.0(WHODAS2.0) Persian Version in People with Multiple Sclerosis
Introduction
Multiple Sclerosis (MS) is an inflammatory, complicated and chronic disease of central nervous system that has affected more than 2 million people at the world and it is the most common neurological cause of disability in young adult [1-3]. Although etiology of this multifactorial and costly disease has been clearly unrecognized, genetic, lack of vitamin D, autoimmune mechanism and environmental factors play a major role to in affecting to MS [4-6].
In Iran, MS prevalence is high (50 per 100000) and it has been occurred in women approximately 3 times more than men. This disabling disease can be lead to a reduction in quality of life and patient’s autonomy, limited the activities, restricted the participation, and it even can be the cause for unemployment, because a results of study has found that the people with MS lost their job after distinguish the disease [1, 7-11]. So, measuring disability levels, activity limitation and participation restriction, instead of impairments seem to be more important to increasing patient’s participation in order to integrating people with disability in community [12].
Although a variety of instruments have been made to measure disability levels, WHODAS2.0 designed and developed according to International Classification of Functioning, Disability and Health (ICF), this instrument developed to show ICF concepts (Activity and Participation chapter) [13-15]. It has been used in order to assess difficulty in activities, disability, functioning, and the interventions efficacy of diseases and disorders (illness, drugs and alcohol consumption, mental disorders and injuries) in clinical and research places [13, 16]. Moreover, the most of studies have shown that WHODAS2.0 has acceptable psychometric properties, and several countries (more than 28) have culturally translated and adapted it [13, 15, 17]. Previous reports have described that the WHODAS2.0 has good psychometric features, including good test-retest reliability, acceptable internal consistency, robust factor structure across culture and different patient populations, good concurrent validity and good responsiveness to change [13, 16, 18, 19]. The psychometric properties of WHODAS2.0 have been investigated in a variety of clinical situation including stroke patients, inflammatory arthritis, low back pain, osteoarthritis, hearing loss, depression, ankylosing spondylitis, psychosis, traumatic brain injury, elderly condition and systemic sclerosis [20-30].
Simplicity to use, little time need to complete and created based on Biopsychosocial model of ICF can be differenced and distinguished it from others instruments [18, 31]. Although studies on psychometric evaluation of WHODAS2.0 have provided valuable knowledge, no study provided an evaluation psychometric Persian version of the WHODAS2.0. So, the aim of this study was to assess psychometric properties (the test-retest reliability, the internal consistencies of reliability, the floor and ceiling effects in every domain, and the construct validity) of the Persian version of WHODAS2.0 in people with MS.
Materials and Methods
This study included two stages. Stage 1 was translated to Persian translation and adaptation English version of WHODAS2.0 to Persian. Stage 2 was a cross-sectional study of data collection to psychometric properties of Persian version of WHODAS2.0 in patients with MS.
Stage 1:
Translation and Adaptation process of WHODAS2.0
The translation permission of WHODAS2.0 into Persian language was obtained from WHO. The instrument was translated and adapted according to WHO guidelines for translation [32]. At first, the English version of the instrument was translated into Persian language by two native translators. Then, in an expert session, including 3 health professions (two physiotherapists and one occupational therapist) and the two Persian translators, discussed and agreed on a unit Persian translation. The backward translation was done by a translator, who mother tongue was English and living in Iran and had not any knowledge about health field, especially on WHODAS2.0.
To explore and confirm the backward translation, the research team compared the original version with the backward one. At the end of the process, the approved instrument, tested on 10 individuals to explore any difficulty in understanding. All participants described there were not any problems and difficulties in comprehension of WHODAS2.0 Persian version.
Stage 2:
Participants
121 patients with MS that above 18 years old, living in Khuzestan, having at least the ability to read and write in Persian, and EDSS range 1-7 were selected and invited to MS association, located in Rehabilitation School in Ahwaz Jundishapour Medical Sciences University, in order to participate in this research. All participants were signed the informed consent form that confirmed by Ethic Committee of Ahwaz Jundishapour Medical Sciences University.
To assessing the construct and concurrent validity and also, the internal consistency reliability of WHODAS2.0, the participants fulfilled the WHODAS2.0 and MSQOL-54 questionnaires. 10 days after the 1st meeting, 60 patients received the WHODAS2.0 to assess the test-retest reliability[24].
Instruments
1. MSQOL-54: The Multiple Sclerosis Quality Of Life-54(MSQOL-54) was designed based on Short Form-36 (SF-36) instrument and made to assess the Health Related Quality of Life (HRQOL) in people with MS. The MSQOL questionnaire was developed by adding 18 especial items on MS areas to 36 items of SF36, and the instrument are evaluated these subscales: physical health, role limitation due to physical problems, role limitation due to emotional problems, pain, emotional well-being, energy, health perceptions, social function, cognitive function, health distress, sexual function, change in health, satisfaction with sexual function and overall quality of life. These 14 subscales are divided into two combination areas (physical and mental health). Scores of 14 and the two combination areas is from 0 to 100, and the higher score showed the higher quality of life in people with MS[33, 34].
2. WHODAS2.0: In this study, the 36-items and self-administrated WHODAS2.0 was used to measuring the functioning and disability. This instrument includes these six subscales: Understanding, Getting around, Self-care, Getting along with people, Life activities, and Participation in society. The questions of WHODAS2.0 is a 5-Likert scale grading from 0 (none) to 4 (extreme or can’t do) and its scoring based on WHO algorithm from 0 (no disability) to 100 (full disability), that the lower score shows less disability[22].
Statistical Analysis
1. Reliability
1.1. Internal consistency
Cranach’s alpha was assessed to determine the internal consistency of WHODAS2.0, a minimum acceptable amount for Cranach’s alpha in an Asian study was obtained above 0.70 (for each subscale)[13].
1.2. Test-Retest Reliability
Interclass correlation coefficient (ICC) through the two way random model (CI=95%) was applied (for every subscales) to examine the test ‘retest reliability for WHODAS2.0[35].
2. Validity
2.1. Concurrent validity
WHODAS2.0 and MSQOL-54 were applied to determine the concurrent validity by assessing the correlation (Pearson coefficient) between subscales of the both instruments. Correlation above 0.70 assumed appropriate (acceptable), if it greater than 0.90 considered excellent[13].
2.2. Ceiling and Floor Effects
Ceiling and floor effects were used to reflect the content validity of WHODAS2.0[12].
2.3. Exploratory and Confirmatory Factor Analysis
Exploratory Factor Analysis (EFA) with Principal Component and Varimax rotation was performed in order to explore the WHODAS2.0 structure. To confirm the structure of the instrument, Confirmatory Factor Analysis (CFA) was applied[12, 18].
Statistical Package for Social Sciences (SPSS) version 16 for windows (SPSS Inc., Chicago, IL, USA) and Lisrel 8.80 were performed to analysis the participant’s data
Result
Demographic variables of participants are displayed in table 1.
1. Reliability
Test-retest reliability was assessed using intraclass correlation coefficient (ICC) two-way random effects model with 95% confidence interval. ICCs ‘ 0.70 were considered satisfactory for test-retest reliability. ICC & 95% CI, mean (SD), alpha Cronbach, ceiling & floor effects of each domain and total score of WHODAS2.0 and MSQoL-54 presented in table 2. The ICC was very good to excellent varied between 0.82 and 0.99 for the six subscales of the WHODAS2.0. Alpha Cronbach was used to assess internal consistency. All domains of the WHODAS 2.0 showed internal consistency above 0.70, the minimum value of acceptable internal consistency. ‘Getting alone’ dimension before the deletion of items concerning intimate relationship and sexual activity displayed poor ” value. WHODAS2.0
Characteristics Values
Gender, n (%)
Male 25(20.7)
Female 95(78.5)
Age , Mean (SD) 33.28”9.77
EDSS, Mean (range) (1-7)
Marital status, n (%)
Unmarried 43(35.5)
Married 76(62.8)
Divorced 2(1.7)
Widowed 0
Occupation, n (%)
Employee 90(74.5)
Unemployed 28(23.1)
Scale/Domain N Mean (SD) ICC (95% CI) Floor (%) Ceiling (%) Cronbach’s
Alpha
WHODAS2.0
Cognition 26.65(22.3) 0.82(0.69-0.89) 19(15.7) 1(0.8) 0.70
Mobility 29.3(25.6) 0.98(0.96-0.99) 26(21.5) 2(1.7) 0.84
Self-care 12.66(19.6) 0.98(0.97-0.99) 68(56.7) 1(0.8) 0.76
Getting along 16.14(19.1) 0.96(0.92-0.98) 34(35.4) 1(1) 0.75
Life activities (household) 24.62(24.9) 0.95(0.92-0.97) 31(25.6) 2(1.7) 0.85
Life activities (work/school) 16.13(20.3) 0.98(0.96-0.99) 35(43.2) 2(2.5) 0.87
Participation 33.54(21) 0.99(0.98-0.99) 8(6.7) 2(1.7) 0.85
Total score 22.5(15.3) 0.98(0.98-0.99) 3(4.6) 1(1.5) 0.94
MSQoL-54
Physical Health Composite 60.8(20.4) ” ” ” 0.88
Mental Health Composite 56.5(22.6) ” ” ” 0.81
Total score 57.41(20.2) ” ” ” 0.90
WHODAS2.0: World Health Organization Disability Assessment Schedule; MSQoL-54: Multiple sclerosis Quality of Life.
*:
Table 3 correlation
WHODAS2.0
Cognition Mobility Self-care Getting along Life activities(household) Life activities(work/school) Participation Total score
MSQoL-54
Physical Health Composite -0.594 -0.624 -0.578 -0.508 -0.509 -0.475 -0.644 -0.744
Mental Health Composite -0.570 -0.459 -0.498 -0.505 -0.399 -0.400 -0.576 -0.655
Total score -0.582 -0.487 -0.510 -0.515 -0.433 -0.453 -0.560 -0.671
Table 4 factor analysis
1 2 3 4 5 6 7
D1:Understanding & Communicating
concentrating 0.762 0.216 0.332
remembering 0.849
finding solutions 0.759 0.265 0.222
learning new task 0.694 0.245
understanding 0.673 0.364 0.254 0.236
conversation 0.702 0.316 0.276
D2: Getting around
Standing 0.336 0.631 0.467
standing up 0.442 0.275 0.583 0.251
moving around 0.487 0.405 0.519
getting out of home 0.406 0.270 0.245 0.699
Walking 0.344 0.359 0.762 0.207
D3: Self Care
washing 0.203 0.725 0.289 0.220
dressing 0.350 0.582 0.310 0.225
eating 0.309 0.478 0.331
staying by yourself 0.652
D4: Getting along with people
dealing with people unknown 0.332 0.724 0.345
maintaining friendship 0.398 0.680 0.241
getting along with people close 0.248 0.838
make new friends 0.838 0.207
sexual activities 0.704 0.260
D5.1: Life activities: household
household responsibilities 0.257 0.596 0.315 0.351 0.213 0.213
doing household tasks well 0.203 0.579 0.537 0.241 0.245
doing housework needed 0.422 0.556 0.280 0.213 0.411
household work done quickly 0.476 0.326 0.356 0.393 0.384
D5.2: Life activities: work or school
day to day work/school 0.849 0.259
doing most important work well 0.304 0.872
getting work done needed 0.306 0.875
getting work done quickly 0.308 0.554 0.416 0.311 0.262
D6: Participation in society
problems in communities 0.243 0.231 0.799
problems because of barriers 0.212 0.324 0.776
living with dignity 0.286 0.344 0.206 0.223 0.289 0.486
time spend on health condition 0.225 0.221 0.676
been emotionally affected 0.289 0.285 0.247 0.532 0.289
drain on financial resources 0.879
problems for the family 0.216 0.775 0.276
problems doing things for relaxation 0.306 0.356 0.308 0.427 0.526
Discussion
This study designed and conducted to examine the psychometric properties of Persian version of WHODAS2.0 (36-items) in people with MS. The result of the present study showed that the Persian version of WHODAS2.0 has excellent psychometric properties. Our data found that the sexual activities question had most missing values and that because up to 30 participants reported who didn’t get married. In spite of the fact that some participants had been married, but they didn’t answer the question (sexual activities question).
Results of this study showed that Cronbach alpha coefficients for each subscales was between 0.70 (understanding and communication) to 0.88 (life activities). Cronbach alpha coefficient for WHODAS2.0 total score was high and it’s about 0.94. Result of this study are greater than Prot”g”s version of WHODAS2.0 on people with musculoskeletal pain (”=0.84)[14], and similar to the study was carried out by Chisolm in people with hearing loss (”=0.94)[21]. Also, Cronbach alpha coefficients for Persian version similar to Taiwan study (”=0.91)[13].
Result for ICC in table 2 shows that correlation coefficients of all subscales are greater than 0.80, and the cognition (D1) and participation in society (D2) subscales had the minimum and maximum amount of ICC (0.82 and 0.99), respectively. Guilera et al (who carried out a study on schizophrenia)[23] argues that the minimum and maximum amount of ICC was for D1 and D2 (0.86 and 0.89), and the findings are similar to Persian version. In the present study, the totally ICC for WHODAS2.0 was 0.98, and it greater than Guilera study. Also in the same vein, Silva et al (Prot”g”s study)[14] reported that the total ICC score for WHODAS2.0 was 0.95 and it similar and consistent to the Persian version. Also, the Taiwan’s study (ICC=0.80) in contrast to present study showed lower intraclass correlation coefficient[13].
Results of floor and ceiling effect analysis showed that Persian version of WHODAS2.0 show the floor effects of ‘Self-care’, ‘Getting along’ and ‘Life activities (work/school)’ domains were over 30%. The study that carried out by Garin[18] showed different and lower floor and ceiling effect for WHODAS2.0 in compare with the result of present study. Chiu and et al (Taiwan study)[13] reported that whole WHODAS2.0 subscales had floor effect more than 35%, especially in Self-care, Getting along and Life activities dimensions that over 40%, but the total floor effect of WHODAS2.0 was 7.2%. The result of this Taiwan study was similar to the Persian version of WHODAS2.0 that showed 4.6% floor effect for WHODAS2.0.
The correlation between WHODAS2.0 and MSQOL-54 confirmed the concurrent validity between the two instruments. Result of correlation has shown in table 3. Compared with other studies, this result is similar to English version of WHODAS2.0 that developed by WHO[16]. The English version of WHODAS2.0 had acceptable correlation between other instruments such as SF36, SF12 and WHOQOL (r=0.43-0.58). The correlation between Persian version of WHODAS2.0 and MSQOL-54 (r=-0.67) was more than the previous studies (Taiwan and Guilera)[13, 23], but smaller than Thomas study[36] that conducted on people with Lymphatic Filariasis (r> 0.7). Magistrale and et al[37] reported moderate correlations between mental health composite of the MSQOL-54 and WHODAS2.0 and strong correlation between physical health composite of the MSQOL-54 and WHODAS2.0 in patients with MS. Results of correlation analysis between WHODAAS2.0 and MSQOL-54 in this study indicated that the Persian version of WHODAS 2.0 show good external construct validity of this instrument.
The result of exploratory factor analysis (EFA) displayed that approximately 75% of total variance was loaded by 7 factors, and it’s greater than English[18] and Japanese versions[38] of WHODAS2.0. Seven factors were detected for Persian version, and it similar to the previous researches such as Taiwan[13], WHO[16] and European[39] studies, but it differs from Italian[40] and English[18] versions that explained 6 factors to WHODAS2.0. Results of CFA in table 5 suggest, Persian version of WHODAS2.0 show acceptable construct validity. Consistent with this finding, Chiu et al[13] reported the traditional Chinese version of the WHODAS 2.0 items loaded greater 0.4 in CFA.
Conclusion
The results of this study indicated that the Persian version of WHODAS 2.0 is a valid and reliable instrument to evaluate functioning and disability for people with MS.
Acknowledgments
This study is part of M.Sc thesis of Mr Shakhi and supported by from the Vice Chancellor for Research Affairs, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. (Grant number: PHT- )
1. D”rr, J., A. D”ring, and F. Paul, Can we prevent or treat multiple sclerosis by individualised vitamin D supply. EPMA J, 2013. 4(1): p. 1-12.
2. Pasquali, L., et al., Plasmatic oxidative stress biomarkers in multiple sclerosis: Relation with clinical and demographic characteristics. Clinical biochemistry, 2015. 48(1): p. 19-23.
3. T”r”k, N., et al., Chemokine receptor V ”32 deletion in multiple sclerosis patients in Csongr”d County in Hungary and the North-B”cska region in Serbia. Human immunology, 2015. 76(1): p. 59-64.
4. Consortium, I.M.S.G. and W.T.C.C.C. 2, Genetic risk and a primary role for cell-mediated immune mechanisms in multiple sclerosis. Nature, 2011. 476(7359): p. 214-219.
5. Inglese, M. and M. Petracca, Therapeutic strategies in multiple sclerosis: A focus on neuroprotection and repair and relevance to schizophrenia. Schizophrenia research, 2015. 161(1): p. 94-101.
6. Zambonin, J.L., et al., Increased mitochondrial content in remyelinated axons: implications for multiple sclerosis. Brain, 2011. 134(7): p. 1901-1913.
7. Fiest, K., et al., Comorbidity is associated with pain-related activity limitations in multiple sclerosis. Multiple sclerosis and related disorders, 2015. 4(5): p. 470-476.
8. Frndak, S.E., et al., Negative work events reported online precede job loss in multiple sclerosis. Journal of the neurological sciences, 2015. 357(1): p. 209-214.
9. Gavelova, M., et al., Importance of an individual’s evaluation of functional status for health-related quality of life in patients with multiple sclerosis. Disability and health journal, 2015.
10. Heesen, C., et al., Patient autonomy in multiple sclerosis’possible goals and assessment strategies. Journal of the neurological sciences, 2013. 331(1): p. 2-9.
11. Turner, A.P., D.R. Kivlahan, and J.K. Haselkorn, Exercise and quality of life among people with multiple sclerosis: looking beyond physical functioning to mental health and participation in life. Archives of physical medicine and rehabilitation, 2009. 90(3): p. 420-428.
12. Negahban, H., et al., The Persian Version of Community Integration Questionnaire in persons with multiple sclerosis: translation, reliability, validity, and factor analysis. Disability and rehabilitation, 2013. 35(17): p. 1453-1459.
13. Chiu, T.-Y., et al., Development of traditional Chinese version of World Health Organization Disability Assessment Schedule 2.0 36’item (WHODAS 2.0) in Taiwan: Validity and reliability analyses. Research in developmental disabilities, 2014. 35(11): p. 2812-2820.
14. Silva, C., et al., Adaptation and validation of WHODAS 2.0 in patients with musculoskeletal pain. Revista de Sa”de P”blica, 2013. 47(4): p. 752-758.
15. Silveira, C., et al., Cross-cultural adaptation of the World Health Organization Disability Assessment Schedule (WHODAS 2.0) into Portuguese abstract. Revista da Associa”o M”dica Brasileira, 2013. 59(3): p. 234-240.
16. ”st”n, T.B., et al., Developing the World Health Organization disability assessment schedule 2.0. Bulletin of the World Health Organization, 2010. 88(11): p. 815-823.
17. Von Korff, M., et al., Modified WHODAS-II provides valid measure of global disability but filter items increased skewness. Journal of clinical epidemiology, 2008. 61(11): p. 1132-1143.
18. Garin, O., et al., Research Validation of the” World Health Organization Disability Assessment Schedule, WHODAS-2″ in patients with chronic diseases. Health and quality of life outcomes, 2010. 8: p. 51.
19. Meesters, J.J., et al., Validity and responsiveness of the World Health Organization Disability Assessment Schedule II to assess disability in rheumatoid arthritis patients. Rheumatology, 2010. 49(2): p. 326-333.
20. Baron, M., et al., The clinimetric properties of the World Health Organization Disability Assessment Schedule II in early inflammatory arthritis. Arthritis Care & Research, 2008. 59(3): p. 382-390.
21. Chisolm, T.H., et al., The WHO-DAS II: psychometric properties in the measurement of functional health status in adults with acquired hearing loss. Trends in Amplification, 2005. 9(3): p. 111-126.
22. Chwastiak, L.A. and M. Von Korff, Disability in depression and back pain: evaluation of the World Health Organization Disability Assessment Schedule (WHO DAS II) in a primary care setting. Journal of clinical epidemiology, 2003. 56(6): p. 507-514.
23. Guilera, G., et al., Utility of the World Health Organization Disability Assessment Schedule II in schizophrenia. Schizophrenia research, 2012. 138(2): p. 240-247.
24. Hudson, M., et al., Quality of life in systemic sclerosis: psychometric properties of the World Health Organization Disability Assessment Schedule II. Arthritis Care & Research, 2008. 59(2): p. 270-278.
25. Kuo, C.-Y., et al., Functioning and Disability Analysis of Patients with Traumatic Brain Injury and Spinal Cord Injury by Using the World Health Organization Disability Assessment Schedule 2.0. International journal of environmental research and public health, 2015. 12(4): p. 4116-4127.
26. Kutlay, ”., et al., Validation of the World Health Organization disability assessment schedule II (WHODAS-II) in patients with osteoarthritis. Rheumatology international, 2011. 31(3): p. 339-346.
27. R”e, C., U. Sveen, and E. Bautz-Holter, Retaining the patient perspective in the International Classification of Functioning, Disability and Health Core Set for low back pain. Patient preference and adherence, 2008. 2: p. 337.
28. Schlote, A., et al., WHODAS II with people after stroke and their relatives. Disability and rehabilitation, 2009. 31(11): p. 855-864.
29. Twomey, C.D., et al., Cross-sectional associations of depressive symptom severity and functioning with health service use by older people in low-and-middle income countries. International journal of environmental research and public health, 2015. 12(4): p. 3774-3792.
30. Van Tubergen, A., et al., Assessment of disability with the World Health Organisation Disability Assessment Schedule II in patients with ankylosing spondylitis. Annals of the Rheumatic Diseases, 2003. 62(2): p. 140-145.
31. ”st”n, T.B., Measuring health and disability: manual for WHO disability assessment schedule WHODAS 2.0. 2010: World Health Organization.
32. Wild, D., et al., Principles of good practice for the translation and cultural adaptation process for patient’reported outcomes (PRO) measures: report of the ISPOR Task Force for Translation and Cultural Adaptation. Value in health, 2005. 8(2): p. 94-104.
33. Ghaem, H., et al., Validity and reliability of the Persian version of the multiple sclerosis quality of life questionnaire. Neurology India, 2007. 55(4): p. 369.
34. Tepavcevic, D., et al., The impact of sexual dysfunction on the quality of life measured by MSQoL-54 in patients with multiple sclerosis. Multiple sclerosis, 2008. 14(8): p. 1131-1136.
35. Mazaheri, M., et al., Reliability and validity of the Persian version of Foot and Ankle Ability Measure (FAAM) to measure functional limitations in patients with foot and ankle disorders. Osteoarthritis and Cartilage, 2010. 18(6): p. 755-759.
36. Thomas, C., et al., Comparison of three quality of life instruments in lymphatic filariasis: DLQI, WHODAS 2.0, and LFSQQ. PLoS Negl Trop Dis, 2014. 8: p. e2716.
37. Magistrale, G., et al., Validation of the World Health Organization Disability Assessment Schedule II (WHODAS-II) in patients with multiple sclerosis. Multiple Sclerosis Journal, 2014: p. 1352458514543732.
38. Tazaki, M., et al., Measuring functional health among the elderly: development of the Japanese version of the World Health Organization Disability Assessment Schedule II. International Journal of Rehabilitation Research, 2014. 37(1): p. 48-53.
39. Buist’Bouwman, M., et al., Psychometric properties of the World Health Organization Disability Assessment Schedule used in the European Study of the Epidemiology of Mental Disorders. International journal of methods in psychiatric research, 2008. 17(4): p. 185-197.
40. Federici, S., et al., World Health Organisation disability assessment schedule II: contribution to the Italian validation. Disability and rehabilitation, 2009. 31(7): p. 553-564.
xt in here…