Longitudinal Assessment of HIV Viral Load Trajectory and Predictors of Virological Failure in a North Central Nigeria ART Cohort

Virological failure in patients on antiretroviral therapy (ART) represents a major challenge to Nigeria's progress toward the UNAIDS 95-95-95 targets, yet cohort data characterising the viral load trajectory and predictors of failure in North Central Nigeria are sparse. This longitudinal retrospective cohort study analyses viral load trajectories from ART initiation over a five-year follow-up period among HIV-positive adults enrolled at the University of Abuja Teaching Hospital, FCT, between 2019 and 2024. Individual patient viral load measurements at 6, 12, 24, 36, 48, and 60 months post-ART initiation will be extracted from the facility's electronic medical records. Virological failure, defined as plasma HIV RNA above 1,000 copies per millilitre on two consecutive measurements, will be the primary outcome. Mixed-effects linear models will describe viral load trajectories, and time-to-event analysis using Cox proportional hazards regression will identify predictors of first virological failure, including regimen type, adherence metrics, baseline CD4 count, and co-morbidities. Existing Nigerian cohort studies are largely cross-sectional, lacking the longitudinal granularity needed to understand suppression dynamics over time. Findings will characterise virological failure patterns in a North Central urban cohort, providing evidence to guide regimen optimisation decisions and inform differentiated ART delivery models aimed at high-risk subgroups. Keywords: HIV viral load, virological failure, ART cohort, longitudinal study, North Central Nigeria