Developing the World Health Organization Disability Assessment Schedule 2.0

Area of Science:

• Health Measurement
• Disability Assessment
• Psychometrics

Background:

• The International Classification of Functioning, Disability and Health (ICF) provides a framework for health and disability.
• A standardized metric is needed for scientific comparability of functioning and disability data across populations.

Purpose of the Study:

• To describe the development of the World Health Organization Disability Assessment Schedule 2.0 (WHODAS 2.0).
• To establish WHODAS 2.0 as a standard metric for measuring functioning and disability aligned with the ICF.
• To ensure scientific comparability of disability measures across diverse populations.

Main Methods:

• Global studies involving over 65,000 respondents from general and patient populations.
• Administration of the WHODAS 2.0 (full 36-item and shortened 12-item versions) by trained interviewers.
• Psychometric evaluation including internal consistency, factor structure, reliability, validity, and responsiveness.

Main Results:

• WHODAS 2.0 demonstrated high internal consistency (Cronbach's alpha: 0.86) and test-retest reliability (ICC: 0.98).
• The instrument showed a stable factor structure, good concurrent validity, Rasch scalability, and responsiveness to change.
• Effect sizes for health interventions ranged from 0.44 to 1.38.

Conclusions:

• WHODAS 2.0 is a robust and easily administered instrument for measuring the impact of health conditions.
• It effectively monitors intervention effectiveness and estimates the burden of mental and physical disorders.
• The tool facilitates scientific comparability of functioning and disability data globally.