Background
Unstable housing has been linked to substance use (SU) and other health outcomes and evidence that SU especially methamphetamine (meth) drives HIV acquisition, has been well described. Yet the interaction between unstable housing and meth use on HIV acquisition is unclear, especially critical for EHE priority jurisdictions such as Los Angeles, which has the second largest population of people experiencing unstable housing in the US. The objective of this study was to examine the synergistic impact of housing instability and meth use on the incidence of HIV infection.
Methods
Data for this analysis are from a cohort study of gay, bisexual, and other men who have sex with men in Los Angeles, CA. Participants were eligible if they were 18-45 years of age, male sex at birth, reported condomless anal intercourse with a male partner in the past 12 months, and tested negative for HIV at baseline. Data from those enrolled from 2014 with at least one follow-up visit through August 2024 were included (n=274; median follow-up 4.6 years). Semiannual visits assessed housing status, SU, and sexual behaviors and collection and testing of biospecimen for STIs/HIV. Kaplan-Meier survival analysis and Cox regression accounting for time varying covariates was used to assess HIV incidence rate and factors associated with HIV seroconversion.
Results
At baseline median age was 28 years, 47% identified as Black and 38% Hispanic/Latine. Past 6-month self-reported meth use was 32% (n=88), unstable housing 34% (n=94), PrEP use 36% (n=99), with 18% (n=50) testing positive for chlamydia, gonorrhea, or infectious syphilis. Twenty participants tested positive for HIV at follow-up (HIV incidence rate=1.6 per 100 person-years (PY) (95% CI: 1.0-2.4)); highest among those who reported both unstable housing and daily meth use (8.0 per 100 PY; 95% CI 3.3-19.2), compared to those who reported daily meth use without unstable housing (2.7 per 100 PY; 95% CI 0.4-19.4) or unstable housing without daily meth use (2.3 per 100 PY; 95% CI 1.0-5.1). Based on cox regression analyses daily meth use and unstable housing were both associated with HIV seroconversion (HR=5.0; 95% CI 1.8-13.7 and HR=3.0; 95% CI 1.3-7.4, respectively (Table).
Conclusions
These findings underscore the powerful interaction between housing instability and daily methamphetamine use, showing there is a multiplicative effect of these factors on HIV risk. Intervening on both housing support and substance use together is essential for reducing HIV transmission.
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