Self-report disability in an international primary care study of psychological illness.

We assessed the replicability of reliability and validity of a brief self-report disability scale, adapted from the Medical Outcomes Survey (short form), in a 15-center, cross-national, multilingual study of psychological illness among primary care patients (n = 5438). Across all 15 centers in the World Health Organization Collaborative Study of Psychological Problems in General Health Care, the reliability of the disability scale was high and individual items were responsive at similar levels of disability. Self-report disability was consistently correlated with disability in work role (including housework) as rated by interviewers according to the Groningen Social Disability Schedule, a semistructured method taking local norms into account. Disability as measured by the self-report questionnaire was also consistently correlated with depressive symptoms as measured by the General Health Questionnaire. At each center, the disability items formed a moderately to strongly hierarchical (Guttman-like) scale. These findings support the feasibility of using self-report disability scales in cross-national primary care research.