Housing instability and hepatitis C seroconversion among injection drug users: A meta-analytic review

Background. Hepatitis C virus (HCV) infection is endemic among injection drug users (IDUs), and is transmitted through the sharing of injection and drug preparation equipment. Having a stable home may facilitate safer injecting and reduced exposure to contaminated blood. Methods. We conducted a systematic review of published and unpublished cohort or case-control studies that analyzed HCV seroincidence in relation to recent homelessness or unstable housing among IDUs, and meta-analyzed results from 8 studies, published between 2001 and 2009, using random effects models. Results. There was a trend towards a significant association: Pooled Relative Risk = 1.25, 95% Confidence Interval = 0.99, 1.59, p = 0.06. Heterogeneity, assessed by I-square and Q statistics was not significant; however, there was wide variability in the definition of housing instability used in the studies included in the analysis. The small number of studies limited the analysis of publication bias, but several studies that did not publish effect measures indicated that associations with housing instability were not significant. Conclusion. Stable housing may provide a safer setting for injection drug use in regard to HCV transmission, or may serve as an indicator of drug users' ability to plan and prepare for injecting safely. Further research is needed to assess potential publication bias in the observed associations.