Initial Heroin Use Patterns Predict 5-Year Relapse: Results from a Longitudinal Cohort Study in Shanghai, China

People start to use heroin in different patterns. This study identified three initial heroin use patterns in a heroin use cohort: No-factor initial pattern (with no factors of initial heroin use), Single-factor initial pattern (with 1 of 3 factors of initial heroin use), and Multiple-factor initial pattern (with 2 or 3 factors of initial heroin use). The cumulative heroin relapse rate was 53.3%, 62.4%, and 72.7% respectively for No-factor, Single-factor, and Multiple-factor initial patterns during the 5-year follow-up. The adjusted hazard ratio (AHR) was 1.401 (95% CI: 1.091–1.799, p = 0.008) in Single-factor initial pattern and 2.381 (95% CI: 1.546–3.668, p < 0.001) in Multiple-factor initial pattern compared to No-factor initial pattern. This study added new evidence to the impact of initial heroin use on long-term relapse risk, which suggested that initial heroin use patterns should not be neglected.