ASSESSING THE COMPETENCE OF PATIENTS WITH ALZHEIMERS-DISEASE UNDER DIFFERENT LEGAL STANDARDS - A PROTOTYPE INSTRUMENT

Objective: To assess empirically the competency of patients with Alzhe imer's disease (AD) to consent to medical treatment under different le gal standards (LSs). Design: Comparison of normal older subjects and p atients with AD on measures of competency to consent to medical treatm ent. Setting: University medical center. Subjects: Normal older contro l subjects (n = 15) and patients with probable AD (n = 29 [15 with mil d and 14 with moderate AD]). Main Outcome Measures: Two specialized cl inical vignettes were developed that test a subject's capacity to cons ent to medical treatment under five well-established LSs for this comp etency: LS1, evidencing treatment choice; LS2, making the reasonable c hoice; LS3, appreciating consequences of choice; LS4, providing ration al reasons for choice; and LS5, understanding treatment situation and choices. Performance on the LSs was compared across control and AD gro ups using Student's t test, chi(2), and analysis of variance. Demented subjects were categorized as competent, marginally competent, or inco mpetent under each LS by using a cutoff score derived from normal cont rol performance. Results: No differences between groups emerged for LS 1 and LS2. Control subjects performed significantly better than patien ts with mild AD on LS4 and LS5, and significantly better than patients with moderate AD on LS3, LS4, and LS5. Patients with mild AD performe d significantly better than patients with moderate AD on LS4 and LS5. With respect to competency status, patients with AD showed a consisten t and progressive pattern of compromise (marginal competence or incomp etence) related to dementia severity and stringency of the LS. Conclus ions: A reliable prototype instrument validly discriminated the compet ency performance and classified the competency status of control subje cts and patients with mild and moderate AD under five LSs for competen cy to consent to medical treatment. While the groups performed equival ently on minimal standards requiring merely a treatment choice (LS1) o r the reasonable treatment choice (LS2), patients with mild AD had dif ficulty with more difficult standards requiring rational reasons (LS4) and understanding treatment information (LS5), and patients with mode rate AD had difficulty with appreciation of consequences (LS3), ration al reasons (LS4), and understanding treatment (LS5). The results raise d the concern that many patients with mild AD may not be competent to consent to treatment and supported the value of standardized clinical vignettes for assessment of competency in dementia.