HIV risk associated with injection drug use in Houston, Texas 2009: A Latent Class Analysis

Background: Injection drug users (IDUs) are at increased risk of HIV infection because they are more likely to engage in high risk injection behaviors (e.g. needle sharing) as well as in high risk sexual behaviors (e.g. exchange sex). This analysis examines factors associated with HIV risk using a latent class approach.

Methods: Our study includes 523 eligible injection drug users, recruited into the 2009 National HIV Behavioral Surveillance project. Using maximum likelihood we calculated the posterior probability of being in an HIV risk class from 4 drug and 5 sexual behaviors separately. We simultaneously fitted separate logistic regression models to identify socio-demographic factors associated with HIV risk class.

Results: We identified 2 HIV drug risk classes: high (57%) and low risk (43%) and 2 sex risk classes: high (49%) and low risk (51%). Compared to the high HIV drug risk class, homeless IDUs (OR=0.34, 95% CI: 0.22-0.53) and IDUs who were arrested in past 12 months (OR=0.63, 95% CI: 0.41-0.95) had lower odds to be in low risk class. Regarding sexual risk, IDUs who visited a doctor in past 12 month had lower odds (OR=0.52, 95% CI: 0.32-0.83) to be in high risk class compared to low risk class.

Conclusions: Our results show that the majority of our IDUs were engaged in high HIV risk behaviors. Though temporality cannot be established due to the cross-sectional study design our findings indicate that homelessness and history of incarceration are associated with HIV risk.