Background: Although people with schizophrenia display impaired abilities for consent, it is not known how much impairment constitutes incapacity. Aims: To assess a method for determining the categorical capacity status of potential participants in schizophrenia research. Method: Expert-judgement validation of capacity thresholds on the sub-scales of the MacArthur Competence Assessment Tool - Clinical Research (MacCAT–CR) was evaluated using receiver operating characteristic (ROC) analysis in 91 people with severe mental illness and 40 controls. Results: The ROC areas under the curve for the understanding, appreciation and reasoning sub-scales of the MacCAT–CR were 0.94 (95% CI 0.88–0.99), 0.85 (95% CI 0.76–0.94) and 0.80 (95% CI 0.70–0.90). These findings yielded negative and positive predictive values of incapacity that can guide the practice of investigators and research ethics committees. Conclusions: By performing such validation studies for a few categories of research with varying risks and benefits, it might be possible to create evidence-based capacity determination guidelines for most schizophrenia research.

Related Topics: Informed consent, Impaired Decision Making, Research ethics

Keywords: schizophrenia, informed consent

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