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.

中文翻译：

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估计抑郁症对越南注射毒品者艾滋病毒传播风险行为的影响：一种因果关系。

注射吸毒者 (PWID) 的抑郁症和艾滋病毒负担很高，但抑郁症对传播风险行为的影响在该人群中尚不清楚。使用因果推理方法，我们分析了 2009-2013 年越南 455 名感染 HIV 的 PWID 的数据。在 2 年内每 6 个月进行一次研究访问，测量过去一周的抑郁症状以及前 3 个月的注射和性行为。严重的抑郁症状（相对于轻度/无症状）增加了注射设备共享（风险差异 [RD] = 3.9 个百分点，95% CI -1.7, 9.6），但不是无安全套性行为（RD = -1.8, 95% CI -6.4, 2.8) 6 个月后报告。同一访问中与注射设备共享的横截面关联（RD = 6.2, 95% CI 1.4, 11.0）强于纵向效应。