Variable judgments of decisional capacity in cognitively impaired research subjects

To compare assessments of the decisional capacity of cognitively impaired patients by research assistants (RAs) and by family caregiver/proxies and to determine whether either or both groups judge capacity differently depending on the specific (hypothetical) research enrollment decision being made.

Cross-sectional.

Three clinics, one each in Ohio, Kentucky, and Illinois.

One hundred forty-nine patients with established dementia diagnoses and their caregiver/proxies.

As part of a longer interview, patients were asked about future enrollment in five hypothetical research projects with varying risks and benefits. After patients reported each decision and reasons for that decision, RAs (using Applebaum and Grisso's four standards) indicated whether the patients were competent to make that decision on their own. In separate interviews, caregiver/proxies were asked for a similar appraisal based on life experience with the patient. RA and proxy judgments were compared.

Capacity judgments by RAs and by caregiver/proxies differed according to specific project for most patients. Agreement between RA and caregiver/proxy judgments varied according to project, but agreement was only fair when tested using kappa (range in data 0.21-0.39). Caregiver/proxies appraised 50 patients as competent for all decisions, and RAs assessed 47 as so. Of these, only 24 were the same patients.

If capacity were assessed anew for each enrollment decision, more potential participants could maintain authority in making those decisions.