Objectives: To examine the capacity, competency, and reasons for enrolling of patients with Alzheimer's disease (AD) and of their caregivers in an early phase AD clinical trial.
Design: Interviews were conducted with patients with AD, nondemented older persons, and caregivers.
Setting: Participants' homes.
Participants: Fifteen patients with mild to moderate AD, 15 age- and education-matched nondemented older persons, and 15 patient caregivers.
Measurements: Capacity was measured using the MacArthur Competency Assessment Tool for Clinical Research (MacCAT-CR); a study coordinator who reviewed audiotapes of the capacity interviews judged competency, and the reasons for a decision were determined by coding the capacity interviews.
Results: On all measures except the ability to make a choice, patients performed worse than controls (understanding: z = 3.2, P =.001; appreciation: z = 2.8, P =.005; reasoning: z = 3.5, P =.0005), and caregivers (understanding: z = 3.8, P =.0002; appreciation: z = 3.0, P =.003; reasoning: z = 3.6, P =.0003). Using the controls' performance to set psychometric criteria to define capacity, the proportions of patients with adequate understanding, appreciation, and reasoning were six of 15 (40%), three of 15 (20%), and five of 15 (33%). All caregivers and nine of the 15 (60%) patients were competent. Reasons for enrolling typically featured the potential benefit to the patients' health or well-being and altruism that was expressed as a desire to help other patients and their families or a desire to contribute to scientific knowledge.
Conclusions: The MacCAT-CR, in particular its understanding scale, is a reliable and valid way to assess patient capacity and competency to enroll in an early-phase clinical trial. Although many patients have significant impairments in their capacity, some mild-stage patients are competent. Reasons for enrolling in an early-phase trial blend an expectation of therapeutic benefit and a desire to help others.