Development of a Computerized Adaptive Testing System of the World Health Organization Disability Assessment Schedule...

Area of Science:

• Gerontology and Rehabilitation Science
• Psychometrics and Health Measurement

Background:

• The World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0) is a comprehensive tool for assessing disability across six life domains.
• The lengthy assessment time of the WHODAS 2.0 can reduce respondent engagement and utility.
• A need exists for more efficient and user-friendly disability assessment tools, particularly for vulnerable populations like individuals with dementia.

Purpose of the Study:

• To develop and validate a computerized adaptive testing system for the WHODAS 2.0 (CAT-WHODAS 2.0) tailored for people with dementia.
• To enhance the efficiency and reliability of disability assessments in this population.

Main Methods:

• A multidimensional Rasch model was employed to analyze fit indices of 27 items from a nationwide disability certification database.
• Item difficulties were examined for sex-based score comparability.
• Simulation studies determined optimal stopping rules to balance reliability and efficiency.

Main Results:

• Twenty-seven items demonstrated satisfactory model fits, with no significant differential item functioning by sex.
• The CAT-WHODAS 2.0 required an average of nine items to achieve high Rasch person reliabilities (.90-.91) across the six domains.
• Excellent concurrent validity was observed, with high correlations to raw domain scores (r=.90-.94) and the item bank (r=.96-.99).

Conclusions:

• The CAT-WHODAS 2.0 offers an efficient, reliable, valid, and sex-unbiased method for assessing disability in individuals with dementia.
• This computerized adaptive testing system presents a valuable alternative for optimizing data collection efficiency in clinical and research settings.
• The CAT-WHODAS 2.0 ensures score comparability with the established 27-item Rasch-calibrated item bank.