Estimating the Effect of Depression on HIV Transmission Risk Behaviors Among People Who Inject Drugs in Vietnam: A Causal Approach

Abstract

The burden of depression and HIV is high among people who inject drugs (PWID), yet the effect of depression on transmission risk behaviors is not well understood in this population. Using causal inference methods, we analyzed data from 455 PWID living with HIV in Vietnam 2009-2013. Study visits every 6 months over 2 years measured depressive symptoms in the past week and injecting and sexual behaviors in the prior 3 months. Severe depressive symptoms (vs. mild/no symptoms) increased injection equipment sharing (risk difference [RD] = 3.9 percentage points, 95% CI -1.7, 9.6) but not condomless sex (RD = -1.8, 95% CI -6.4, 2.8) as reported 6 months later. The cross-sectional association with injection equipment sharing at the same visit (RD = 6.2, 95% CI 1.4, 11.0) was stronger than the longitudinal effect. Interventions on depression among PWID may decrease sharing of injection equipment and the corresponding risk of HIV transmission.Clinical trial registration ClinicalTrials.gov NCT01689545.

Keywords: Depressive symptoms; HIV transmission; Injecting behavior; Marginal structural models; People who inject drugs; Sexual behavior.

Fig. 1

Weighted risks of any sharing of injection equipment and any condomless sex by depressive symptoms, estimated among 455 PWID with HIV in Thai Nguyen, Vietnam. Severe depressive symptoms were defined as CES-D ≥ 23; no severe symptoms were CES-D < 23. We evaluated the risk behavior outcome at the next 6-month visit (longitudinal) to estimate the causal effect, and for comparison, we modeled the association at the same visit (cross-sectional)

Fig. 2

Weighted risks of any sharing of injection equipment and any condomless sex exploring three levels of depressive symptoms. The three levels of symptoms were severe (CES-D ≥ 23), mild (16 ≤ CESD ≤ 22), and none (CES-D < 16). For each comparison, we evaluated the risk behavior outcome at the next 6-month visit (longitudinal) to estimate the causal effect as well as the association at the same visit (cross-sectional)