Edinburgh Napier University

  Background: The evidence on factors that may influence treatment decisional capacity (‘capacity) in psychosis has yet to be comprehensively synthesised, which limits the development of effective strategies to improve or support it.
Aims: To determine the direction, magnitude and reliability of the relationship between capacity in psychosis and a range of clinical, demographic and treatment related factors, thus providing a thorough synthesis of current knowledge.
Method: We did a systematic review, meta-analytical and narrative synthesis of factors that help or hinder treatment decision-making capacity in psychosis (PROSPERO registration CRD42015025568), assessing the direction, magnitude, significance and reliability of reported associations.
Results: We identified 23 relevant studies (N=1823). Psychotic symptoms had small, moderate and strong associations with appreciation, understanding, and reasoning, respectively. Both verbal cognitive functioning and duration of education had small to moderate correlations with understanding and reasoning. Better capacity was also associated with better insight, better metacognitive ability, higher anxiety and lower perceived coercion. No linear relationship with depression was observed. Interventions linked to improved capacity over time were inpatient care (including antipsychotic treatment), information-simplification, shared decision-making and metacognitive training.
Conclusion: This synthesis of over 25 years of research provides a comprehensive assessment of factors that may help or hinder treatment decision-making capacity in psychosis. Although much is known about the role of symptoms and other clinical variables, effective and acceptable psychological interventions to support capacity in this group are lacking.