Assessment of Capacity to Consent to Research Among Psychiatric Outpatients: Prevalence and Associated Factors

Abstract

Mental capacity is an emerging ethical legal concept in psychiatric settings but its relation to clinical parameters remains yet uncertain. The aim of this study is to evaluate the association between capacity to consent research and different psychiatric disorders and to characterize predictors of impairments in research decision-making capacity across diagnostic groups in a cross-sectional study. 139 consecutively referred outpatients with DSM-IV TR diagnoses of psychotic, mood and anxiety disorders were interviewed and a binary judgment of incapacity was made guided by the MacArthur competence assessment tool for consent research (MacCAT-CR). Demographics and clinical information were assessed by cases notes. Patients with anxiety disorders performed the best on the MacCAT-CR, and patients with psychotic disorders had the worst performance, however, there was considerable heterogeneity within each group. Cognitive impairment and global functioning were strongly correlated with MacCAT-CR subscales scores. 30.6% participants lacked research-related decisional capacity. Low Understanding score OR 0.07 (IC 95% 0.01-0.32) and Low Reasoning score OR 0.30 (IC 95% 0.11-0.82) were the factors most closely associated with lack of capacity. No absolute statements about decisional capacity can be driven merely due to the diagnosis. We found several risk factors which may be considered to decide which populations may require more thorough capacity assessments. The issues under consideration in the present study are by no means unique to people with psychiatric conditions. Ignoring this caveat, risks further inappropriate stigmatization of those with serious mental illness.

Keywords: Clinical judgment; Decision making; Informed consent; Mental capacity; Mental disorders; Research ethics.