Sex disparities in HIV treatment outcomes among adolescents in Nigeria: a multistate retrospective cohort study

Background Adolescents living with HIV experience lower retention and viral suppression than other age groups despite expanded access to antiretroviral therapy (ART), particularly in sub-Saharan Africa. Evidence suggests that sex differences may influence treatment outcomes; however, sex-disaggregated analyses from routine program settings in Nigeria remain limited. This study examined sex disparities in HIV treatment outcomes and identified clinical and programmatic factors associated with retention and viral suppression among adolescents receiving ART. Methods We conducted a multistate retrospective cohort study using routinely collected electronic medical record data from adolescents aged 10–19 years who initiated ART between October 2022 and September 2024 across 479 health facilities in Southwest and Northcentral Nigeria. De-identified data were extracted from the Nigeria Medical Records System. Primary outcomes were retention in care at 6 and 12 months after ART initiation and viral suppression, defined as viral load < 1000 copies/mL. Associations between sex and treatment outcomes were assessed using bivariate analyses and multivariable logistic regression. Kaplan–Meier survival analysis evaluated time to loss to follow-up. Results A total of 964 adolescents were included (50% female), with a median age of 16 years. Females had higher baseline CD4 counts than males (p < 0.001), while WHO clinical stage did not differ by sex. Retention at 6 months was 95.6% among males and 97.5% among females (p = 0.111), declining to 86.9% and 88.6% at 12 months, respectively (p = 0.432). Viral suppression was higher among females at 6 months (87.8% vs. 83.0%; p = 0.036) and 12 months (89.6% vs. 83.8%; p = 0.008). After adjustment, sex was not independently associated with retention or viral suppression. Multi-month dispensing, baseline CD4 count, ART regimen, and year of ART initiation were significantly associated with treatment outcomes. Time to loss to follow-up did not differ between sexes (log-rank p = 0.931). Conclusion Although female adolescents demonstrated higher unadjusted viral suppression rates, sex was not an independent predictor of treatment outcomes after adjustment for clinical and programmatic factors. Service delivery characteristics and baseline clinical status were more strongly associated with retention and viral suppression. Strengthening differentiated service delivery and optimizing clinical management may improve adolescent HIV outcomes in routine care settings.