Consistency of physicians' legal standard and personal judgments of competency in patients with Alzheimer's disease

OBJECTIVES: To investigate the consistency of physician judgments of treatm ent consent capacity (competency) for patients with Alzheimer's disease (AD ) when specific legal standards (LS) for competency are used, and to identi fy the LS most clinically relevant to experienced physicians. DESIGN: Control and AD patient participants were videotaped being administe red a measure of capacity to consent to medical treatment. Study physicians viewed videotapes of these assessments individually and made competency ju dgments for each participant under different LS followed by their own perso nal judgment of competency. SETTING: A university medical center. PARTICIPANTS: Participants were 10 older controls and 21 patients with AD ( 10 with mild and 11 with moderate AD). Five physicians with experience asse ssing the competency of AD patients were recruited from the geriatric psych iatry, geriatric medicine, and neurology services of a university medical c enter. MEASUREMENTS: The 31 participants were videotaped performing on a measure o f treatment consent capacity (Capacity to Consent to Treatment Instrument) (CCTI). The CCTI consists of two clinical vignettes (A-neoplasm and B-cardi ac) that test competency under five LS. Vignette A and B assessments were v ideotaped separately for each participant (total videotapes for sample = 62 ). Each study physician viewed each videotaped vignette individually, made judgments under each of the LS (competent or incompetent), and then made hi s/her own personal competency judgment. Physicians were blinded to particip ant diagnosis. Within participant group, consistency of physician judgments was evaluated across LS and personal judgments using percentage agreement and kappa. Agreement between personal and LS judgments for the AD group was evaluated for each physician using logistic regression. RESULTS: As expected, physicians as a group generally demonstrated very hig h percentage agreement in their LS and personal competency judgments for th e control group. For the AD group, mean percentage judgment agreement among physicians ranged from a high of 84% (LS1) (evidencing a treatment choice) to a low of 67% (LS3) (appreciating consequences of treatment choice). Mea n percentage agreement for personal competency judgments was 76%. For the A D sample, kappa analyses for physicians as a group demonstrated significant agreement not attributable to chance for LSS (understanding treatment situ ation/choices) (k = 0.57, P = .001), LS4 (providing rational reasons for tr eatment choice) (k = 0.39, P = .04), and also for personal judgments (k = 0 .48, P =.009). Analysis of LS judgment agreement within physician indicated that physicians applied the LS as discrete standards. Within-physician and for the AD sample, personal competency judgments were associated significa ntly with judgments on LSS (P = .001), LS4 (P = .004), and LS3 (P < .04). CONCLUSIONS: Experienced physicians demonstrated significant agreement asse ssing competency in AD patients when judgments were based upon specific leg al standards. Personal competency judgments of physicians showed a substant ially higher level of agreement than found in a previous study, where speci fic LS were not used. These results suggest that consistency of physician c ompetency judgments can be enhanced if they are guided by knowledge of spec ific LS. Physicians' personal competency judgments were most closely associ ated with comprehension and reasoning LS, the most conservative and clinica lly appropriate standards for deciding competency.