[The assessment of competence in cognitively impaired elderly persons: a closer look at the vignette method]

This article focuses on the assessment of competence of elderly persons both with and without cognitive impairment. In total 113 patients of a geriatric clinic were interviewed. Competence was assessed by using two clinical vignettes, representing respectively a hypothetical treatment situation with mild consequences (endoscopy) and one with severe consequences (operation for colon cancer). Competence was evaluated using the following standards: the ability to evidence a choice, the ability to understand a situation, the ability to reason about a choice, and the ability to appreciate a situation. In the vignette with mild consequences, elderly persons with cognitive impairment performed significantly worse on understanding, reasoning and appreciation than elderly persons without cognitive impairment. In the vignette with severe consequences, elderly persons with cognitive impairment performed significantly worse only on understanding as compared to elderly persons without cognitive impairment. No differences were found for reasoning and appreciation between the cognitively impaired and non-impaired elderly persons. We conclude that competence is less limited by cognitive impairment when assessed in a treatment situation with severe consequences. Therefore, the use of hypothetical vignettes should be carefully reconsidered.