Demographic Risk Factors for Substance-Induced psychosis Rehabilitation Relapse Among Adolescents in Zimbabwe: A Proportional Hazards Modeling Study

Substance-induced psychosis rehabilitation relapse among adolescents remains a significant public health challenge in Zimbabwe. This study aimed to identify and evaluate demographic risk factors influencing relapse using a survival analysis approach. A retrospective cohort design was applied, involving 3,135 adolescents aged 12–17 admitted to four national psychiatric hospitals between 2019 and 2023. A Cox proportional hazards regression model was used to analyze time-to-relapse, with hazard ratios (HRs) and 95% confidence intervals (CIs) quantifying the effects of demographic predictors. Sensitivity analysis was conducted using the Impact Threshold for a Confounding Variable (ITCV) and Robustness Index Ratio (RIR) to assess the reliability of findings. From the findings, high-risk predictors included male gender (HR = 3.64, 95% CI [2.50, 4.82]), urban residence (HR = 16.16, 95% CI [9.96, 26.22]), family history of substance use (HR = 12.44, 95% CI [9.36, 17.55]), and poly-substance use (HR = 11.59, 95% CI [10.11, 12.27]). Moderate-risk factors included age (HR = 2.87, 95% CI [1.82, 3.93]), secondary education (HR = 2.62, 95% CI [1.50, 5.75]), and mental health history (HR = 6.36, 95% CI [4.29, 9.45]). Low-risk factors such as rural residence and treatment duration demonstrated limited protective effects. The model explained 45% of relapse variability (Nagelkerke’s R² = 0.45). While demographic predictors provide valuable insights, relapse risk is determined by a complex interplay of demographic, systemic, and contextual factors. These findings inform targeted policies and programming to address adolescent substance use and improve rehabilitation outcomes.