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World Health Organization Disability Assessment Schedule (WHODAS)
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Supplemental: Huntington’s Disease (HD)
Exploratory: Facioscapulohumeral Dystrophy (FSHD) and Myalgic encephalomyelitis/Chronic fatigue syndrome (ME/CFS)
Short Description of Instrument
The World Health Organization Disability Assessment Schedule 2.0 (WHODAS) is a multidimensional measure of disability. It consists of 36 items in six domains: understanding and communicating, getting around, self-care, getting along with people, life activities, and participation in society. It was cross-culturally developed and field tested in 16 languages in 14 countries. This scale is the recommended method to accompany all diseases in the International Classification of Disease.
The 12-item version takes 5 minutes to administer, while the 36-item versions take 20 minutes. Available versions include self-report, proxy-administered, and interviewer-administered.
This instrument is cross-culturally developed, and applicable across the spectrum of cultural and educational backgrounds. To date, it has only been used in a handful of studies in HD. There is evidence to suggest that the 12-item version may have better psychometric properties than the 36-item version in HD (Kim et al., 2015).
Results provide a profile of functioning across the domains, as well as an overall disability score. Different scoring methods are available, including a simple summation scoring method and a more complex, weighted method of scoring.
Psychometric Properties
Psychometric testing of the WHODAS 2.0 has been rigorous and extensive. In 1998, an earlier draft (89 items) was tested in field trials in 21 sites and 19 countries. Based on psychometric analyses and further field testing in early 1999, the measure was shortened to 36 items, and a 12-item screening questionnaire was also developed. In late 1999, the WHODAS 2.0 underwent reliability and validity testing in 16 centres across 14 countries.
The WHODAS 2.0 has been examined in prodromal and manifest HD in multiple studies. In a study of the 36-item version spanning three years, Downing et al (2014) showed (in a sample of 726 people with prodromal HD and 630 companion participants) that internal consistency for the self-report of prodomal participants, along with the proxy report by their companions was excellent, as Cronbach’s alpha was 0.92 for both. Validity was demonstrated as the self- and proxy reports of those with a high disease burden showed worse functioning, along with declines in functioning over time for those that were medium- and high-burden prodomal participants. In addition, when compared to the Total Functional Capacity Scale, the WHODAS resulted in larger declines in those with medium disease burden relative to controls. This suggests that the WHODAS may be useful in clinical trials for earlier stages of prodomal HD as it may be more sensitive to change at these stages.
A second study compared the 12-item version to the 36-item version (in the same sample of 726 people with prodromal HD and 630 companions.; Kim et al 2015) and demonstrated that the 12-item version can be useful in prodomal HD, especially for those with medium- and/or high-disease burden. The 12-item version was able to detect longitudinal change better than the 36-item version of the WHODAS.
The reliability and construct validity of the 12-item WHODAS were studied in those with both prodomal and manifest HD (this sample included 190 people with prodromal HD, 196 people with early-stage HD, and 89 people with later-stage HD (Carlozzi et al., 2015). The reliability of internal consistency was shown with internal consistency of 0.94. When the WHODAS was compared with other health-related quality of life assessments (e.g., EQ5D), there were moderate significant correlations, which showed convergent validity.
ME/CFS Specific: Scale has been widely used and extensively studied in various diseases and geographical locations. Thus it should be strongly considered for use in any ME/CFS studies where disability is being assessed. It may be advisable to use the 36-question version for consistency across studies, although the 12-question version requires less effort.
Advantages: Scale has been extensively used and validated in a variety of disease settings and is intended to be cross-cultural. Thus it may serve as a 'non-biased' scale for comparison with normal individuals or individuals with other diseases.
Limitations: Not designed specifically with ME/CFS in mind. Number of studies involving ME/CFS in which scale has been used is very limited. Evaluation of function within the home is limited. Thus, for internal comparison of disability amongst ME/CFS patients it may not be optimal, however could be usable even in this setting.
Carlozzi NE, Kratz AL, Downing NR, Goodnight S, Miner JA, Migliore N, Paulsen JS. Validity of the 12-item World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) in individuals with Huntington disease (HD). Qual Life Res. 2015;24(8):1963–1971.
Downing NR, Kim JI, Williams JK, Long JD, Mills JA, Paulsen JS; PREDICT-HD Investigators and Coordinators of the Huntington Study Group. WHODAS 2.0 in prodromal Huntington disease: measures of functioning in neuropsychiatric disease. Eur J Hum Genet. 2014;22(8):958–963.
Kim JI, Long JD, Mills JA, Downing N, Williams JK, Paulsen JS; PREDICT-HD Investigators and Coordinators of the Huntington Study Group. Performance of the 12-item WHODAS 2.0 in prodromal Huntington disease. Eur J Hum Genet. 2015;23(11):1584–1587.
Recommended Instrument for
Recommended Instrument for: FSHD, HD and ME/CFS
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