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Comparative Study
. 2008 Jul;16(7):568-74.
doi: 10.1097/JGP.0b013e318172b406. Epub 2008 Jun 12.

Interpreting the clinical significance of capacity scores for informed consent in Alzheimer disease clinical trials

Jason Karlawish  1 , Scott Y H Kim, David Knopman, Christopher H van Dyck, Bryan D James, Daniel Marson
Affiliations
Comparative Study

Interpreting the clinical significance of capacity scores for informed consent in Alzheimer disease clinical trials

Jason Karlawish et al. Am J Geriatr Psychiatry. 2008 Jul.

Abstract

Objective: Among Alzheimer disease (AD) patients enrolled in a clinical trial, the authors assessed the ability of a standardized capacity assessment procedure to identify persons who are capable of giving their own informed consent.

Design: Cross-sectional interview.

Setting: Thirteen sites participating in a randomized and placebo controlled study of simvastatin for the treatment of mild to moderate AD.

Participants: Persons with mild to moderate AD and their study partners enrolled in the simvastatin clinical trial.

Measurements: Interviews to assess decision-making capacity using the MacArthur Competency Assessment Tool for Clinical Research (MacCAT-CR).

Results: Judges blinded to the subject's clinical status had a high rate of agreement on patients capable of giving their own informed consent (kappa = 0.73). The understanding subscale had the best receiver operator characteristic and an analysis of positive and negative predictive values over a range of hypothetical prevalences of incapacity to consent demonstrated the value of a range of understanding cut-points.

Conclusion: Among mild to moderate AD patients, enrolled in an actual clinical trial, these results suggest evidence based guidelines for using the MacCAT-CR understanding subscale to help guide judgments about whether a patient has the capacity to consent.

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Conflict of interest statement

Dr. Marson and Dr. Kim report no conflicts of interest.

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