Background: Female sex workers (FSWs) are at high risk for HIV infection and face unique barriers to receiving and adhering to testing and treatment. Early viral suppression and consistent viral load testing are critical to optimizing health and reducing transmission in this population. However, the factors associated with testing and successful viral suppression among FSWs are poorly understood, especially in Sub-Saharan Africa. Our study aimed to examine factors, including social, demographic, and clinical characteristics, associated with viral load testing and suppression among female sex workers initiating antiretroviral therapy in Nigeria.

Methods: In this retrospective study, we analyzed routine programmatic data from FSWs enrolled in the National HIV Key Populations (KP) program in Nigeria. We included FSWs who were newly diagnosed with HIV and registered between January 2016 and January 2022. Primary outcomes of interest were a), receiving a viral load test at any point after treatment initiation and b), viral suppression (<1000 copies/ml) at the test closest to 6 months after treatment initiation. To identify factors associated with the outcomes of interest, we used univariable and multivariable logistic regression, with random intercepts for care facilities, and multiple imputation for missing values.

Findings: Out of 34,976 FSWs, 97.1% (n = 33,945) received at least one viral load test, with 94.5% (n = 32,092) indicating viral suppression. The odds of receiving at least one viral load test were higher for those who entered treatment in more recent years, those with formal education and those with advanced HIV stages at baseline (adjusted odds ratios [aOR]: 1.17 [1.14-1.19] for those who entered treatment in 2020 vs. 2016; 1.02 [1.01-1.03] for post-secondary vs. no education; and 1.05 [1.01-1.10] for WHO clinical stage 3/4 vs. stage 1 respectively). The odds of successful viral suppression were higher for those who entered treatment in more recent years, but lower for those with advanced HIV stages at baseline (aOR: 1.13 [1.09-1.18] for 2022 vs. 2016; and 0.92 [0.87-0.98] for WHO clinical stage 3/4 vs. stage 1 respectively).

Conclusions: The study underscored the relevance of timely diagnosis and ART initiation for optimal outcomes among HIV-positive FSWs in Nigeria. We also observed significant improvements in the likelihood of early viral load testing and suppression over the study period, reflecting advancements in the KP program. Further research should clarify factors driving these trends to further strengthen the HIV care pipeline for female sex workers.