Purpose of Review
This systematic review examines the association between co-occurring psychotic disorders and Opioid Agonist Therapy (OAT) outcomes in Opioid Use Disorder (OUD).

Recent Findings
We searched eight databases and reference lists up to March 20, 2024, for observational studies comparing OAT outcomes in patients with OUD with and without psychotic disorders. 21 studies with 17,623 participants were included, all exhibiting a low to moderate overall risk of bias. The results suggested that patients with OUD and psychotic disorders had significantly poorer OAT retention than those with OUD without psychotic disorders [odds ratio (OR) = 0.65; 95% confidence interval (CI): 0.57–0.74; P < 0.05]. Subgroup analysis identified study period as a source of heterogeneity, with no significant publication bias. No significant evidence suggested that co-occurring psychotic disorders were associated with illicit drug use, including opioids (OR = 1.05; 95% CI: 0.50–2.23; P = 0.90), amphetamines [relative risk (RR) = 1.09; 95% CI: 0.45–2.67; P = 0.84], cannabis (OR = 1.48; 95% CI: 0.99–2.21; P = 0.06), cocaine (RR = 1.19; 95% CI: 0.43–3.25; P = 0.74), and polydrug use (OR = 1.05; 95% CI: 0.40–2.72; P = 0.93). Sensitivity analysis confirmed the robustness of all pooled results except for cannabis use.

Summary
Analyzing data from 21 studies involving 17,623 participants, we found that patients with OUD and psychotic disorders had significantly poorer OAT retention compared to those with OUD without psychotic disorders. However, no significant association was found between co-occurring psychotic disorders and illicit drug use.