Disability in the oldest old: "Can do" or "do do"?

OBJECTIVE: To investigate the discrepancies between outcomes for competence (can do) and actual performance (do do) in activities of daily living (ADL s). DESIGN: Baseline measurements of a population-based follow-up study. SETTING: Leiden 85-Plus Study, the Netherlands. PARTICIPANTS: Five hundred and ninety-nine persons, age 85. The response ra te was 86%. MEASUREMENTS: Face-to-face interviews. Measurements of competence and actua l performance were based on the Groningen Activity Restriction Scale. Help received was assessed for several domains. Prevalence rates for disability were assessed according to the concepts of both competence and actual perfo rmance. Analysis was performed separately for basic activities of daily liv ing (BADLs) and instrumental activities of daily living (IADLs). RESULTS: Seventy-seven percent of the oldest old were competent to perform all the BADLs and performed them regularly. Fifteen percent were not compet ent to perform certain BADLs independently but performed them regularly wit h help from others. The prevalence of disability defined as inability in on e or more BADLs was 22% for women and 10% for men. The prevalence of disabi lity defined as inactivity in one or more BADLs was 16% for women and 17% f or men. Only 5% of the oldest old were competent to perform all IADLs and p erformed them regularly. In spite of being competent, 70% did not perform c ertain IADLs regularly. The prevalence of disability defined as inability i n one or more IADLs was 64% for women and 55% for men. The prevalence of di sability defined as inactivity in one or more IADLs was 92% for women and 9 8 % for men. CONCLUSION: The structural discrepancies between the outcomes of competence and actual performance have important consequences when estimating disabil ity in old people. Promoting actual performance in IADLs may reduce disabil ity.