CONSISTENCY OF PHYSICIAN JUDGMENTS OF CAPACITY TO CONSENT IN MILD ALZHEIMERS-DISEASE

OBJECTIVE: To investigate the agreement of physician judgments of capa city to consent to treatment for normal and demented older adults. DES IGN: Subjects were individually administered a standardized consent ca pacity interview. Physicians viewed videotapes of these interviews and made judgments of capacity to consent to treatment. SETTING: Universi ty medical center. PARTICIPANTS: Subjects assessed for competency (N=4 5) were 16 normal older controls and 29 patients with mild Alzheimer's disease (AD). Five medical center physicians with experience assessin g the competency of dementia patients were recruited from the specialt ies of geriatric psychiatry, geriatric medicine, and neurology. MEASUR EMENTS: Subjects were videotaped responding to a standardized consent capacity interview (SCCI) designed to evaluate capacity to consent to treatment. Study physicians blinded to subject diagnosis individually viewed each SCCI videotape and made a judgment of competent or incompe tent to consent. Agreement of physician judgments was evaluated using percentage agreement, kappa, and logistic regression. RESULTS: Compete ncy judgments of physicians showed high agreement for controls but low agreement for AD patients. Physicians as a group achieved 98% judgmen t agreement for the controls but only 56% judgment agreement for the m ild AD patients. The physician group kappa for controls was 1.00 (P<.0 001) and differed significantly (P<.0001) from the physician group kap pa of .14 (P = .44) for AD patients, indicative of a real difference i n the ability of the study physicians to judge consistently competency across the two groups. Similarly, logistic regression analysis showed significant variability in physician judgments for the AD group (chi( 2)=63.8, P<.0001) but not for the control group (chi(2)=4.1, P=1.00). Within the AD group, pairwise analyses revealed significant judgment d isagreement (P < .01) for seven of the 10 physician pairs. CONCLUSIONS : Experienced physicians demonstrated significant agreement judging th e competency of older controls, but significant disagreement judging t he competency of mild AD patients. Physician judgment currently does n ot represent a gold standard for determining consent capacity of demen tia patients. Standardized assessment instruments and clinical trainin g may improve the agreement and accuracy of physician competency judgm ents.