Baseline benzodiazepine exposure is associated with greater risk of transition in clinical high-risk for psychosis (CHR-P): a meta-analysis

Background: Emerging meta-analytical evidence indicates that baseline exposure to antipsychotics and to antidepressants in individuals at clinical high-risk for psychosis (CHR-P) have opposite prognostic effects as regards imminent transition to psychosis, with antipsychotics associated with higher risk and antidepressants associated with a lower risk in comparison to not-exposed individuals. Despite their common use, baseline exposure to benzodiazepines (BDZ) in CHR-P has surprisingly received poor attention as a potential risk modulator for transition to psychosis. The current systematic review and meta-analysis were performed to fix such a knowledge gap. Methods: Systematic scrutiny of Medline and Cochrane library, performed up to 31 December 2022, searching for English-language studies on CHR-P reporting numeric data about the sample, the transition outcome at a predefined follow-up time and raw data on BDZ baseline exposure in relation to such outcome. Results: Of 1893 identified records, five studies were included in the systematic review and meta-analysis. The proportion of participants with exposure to BDZ at baseline ranged from 5.5% (one study) to 46.2%, with an average of 16.8%. At the end of the period of observation, i.e., the follow-up as reported in the study, 28.4% [95% confidence interval (CI) 19.7-39.1%] participants developed psychosis among the BDZ-exposed against 9.3% (7.3 to 11.9%) among the controls. CHR-P participants who were already under BDZ treatment at baseline had more than double chance of transition to psychosis than CHR-P participants who were BDZ-naïve. The risk ratio (RR) was 2.42 (95% CI 1.38-4.23) in the common effects model (z = 3.09; p = 0.002), and 2.40 (1.53 to 3.77) in the random-effects model (z = 5.40; p = 0.006; tau-squared = 0.0). There was no relevant heterogeneity: Cochran's Q = 1.49; df = 4; p = 0.828; I2 = 0.0% (95% CI 0.0-79%). Quality was good in four studies. Conclusions: Ongoing BDZ exposure at inception in CHR-P is associated with a higher risk of transition to psychosis at follow up. This meta-analytic association, which echoes a similar effect of baseline antipsychotic exposure, plausibly indicates that the clinicians' prescription of pharmacological intervention captures some form of prognostically-relevant information (e.g. an anxiety permeated mental state requiring BDZ prescription) that are not adequately encompassed by current CHR-P categorical criteria.