Importance: Estimating the current likelihood of transitioning from a clinical high risk for psychosis (CHR-P) to psychosis holds paramount importance for preventive care and applied research.
Objective: To quantitatively examine the consistency and magnitude of transition risk to psychosis in individuals at CHR-P.
Data sources: PubMed and Web of Science databases until November 1, 2020. Manual search of references from previous articles.
Study selection: Longitudinal studies reporting transition risks in individuals at CHR-P.
Data extraction and synthesis: Meta-analysis compliant with Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and Meta-analysis of Observational Studies in Epidemiology (MOOSE) reporting guidelines; independent data extraction, manually and through digitalization of Kaplan-Meier curves.
Main outcome and measures: Primary effect size was cumulative risk of transition to psychosis at 0.5, 1, 1.5, 2, 2.5, 3, 4, and more than 4 years' follow-up, estimated using the numbers of individuals at CHR-P transitioning to psychosis at each time point. These analyses were complemented by meta-analytical Kaplan-Meier curves and speed of transition to psychosis (hazard rate). Random-effects meta-analysis, between-study heterogeneity analysis, study quality assessment, and meta-regressions were conducted.
Results: A total of 130 studies and 9222 individuals at CHR-P were included. The mean (SD) age was 20.3 (4.4) years, and 5100 individuals (55.3%) were male. The cumulative transition risk was 0.09 (95% CI, 0.07-0.10; k = 37; n = 6485) at 0.5 years, 0.15 (95% CI, 0.13-0.16; k = 53; n = 7907) at 1 year, 0.20 (95% CI, 0.17-0.22; k = 30; n = 5488) at 1.5 years, 0.19 (95% CI, 0.17-0.22; k = 44; n = 7351) at 2 years, 0.25 (95% CI, 0.21-0.29; k = 19; n = 3114) at 2.5 years, 0.25 (95% CI, 0.22-0.29; k = 29; n = 4029) at 3 years, 0.27 (95% CI, 0.23-0.30; k = 16; n = 2926) at 4 years, and 0.28 (95% CI, 0.20-0.37; k = 14; n = 2301) at more than 4 years. The cumulative Kaplan-Meier transition risk was 0.08 (95% CI, 0.08-0.09; n = 4860) at 0.5 years, 0.14 (95% CI, 0.13-0.15; n = 3408) at 1 year, 0.17 (95% CI, 0.16-0.19; n = 2892) at 1.5 years, 0.20 (95% CI, 0.19-0.21; n = 2357) at 2 years, 0.25 (95% CI, 0.23-0.26; n = 1444) at 2.5 years, 0.27 (95% CI, 0.25-0.28; n = 1029) at 3 years, 0.28 (95% CI, 0.26-0.29; n = 808) at 3.5 years, 0.29 (95% CI, 0.27-0.30; n = 737) at 4 years, and 0.35 (95% CI, 0.32-0.38; n = 114) at 10 years. The hazard rate only plateaued at 4 years' follow-up. Meta-regressions showed that a lower proportion of female individuals (β = -0.02; 95% CI, -0.04 to -0.01) and a higher proportion of brief limited intermittent psychotic symptoms (β = 0.02; 95% CI, 0.01-0.03) were associated with an increase in transition risk. Heterogeneity across the studies was high (I2 range, 77.91% to 95.73%).
Conclusions and relevance: In this meta-analysis, 25% of individuals at CHR-P developed psychosis within 3 years. Transition risk continued increasing in the long term. Extended clinical monitoring and preventive care may be beneficial in this patient population.