Incidence and factors associated with viral suppression among adults with HIV and viral load ≥1,000 copies/mL receiving antiretroviral therapy in Southern Ethiopia: a retrospective cohort study

Viral suppression reduces human immunodeficiency virus (HIV) transmission and improves health outcomes. However, evidence on the incidence rate, time to, and factors associated with viral suppression among adults receiving antiretroviral therapy (ART) with a viral load ≥1,000 copies/mL remains limited in southern Ethiopia. We estimated the incidence rate and time to viral suppression and identified associated factors among adults on ART with a viral load ≥1,000 copies/mL. We conducted a retrospective cohort study of 344 adults receiving ART at Bule Hora and Dilla Teaching Hospitals from January 2018 to December 2024. We defined cohort entry as the first documented viral load ≥1,000 copies/mL after at least six months of ART and viral suppression as a subsequent viral load < 1,000 copies/mL. We estimated the incidence rate and median time to suppression using survival analysis and identified associated factors using Cox proportional hazards regression. Of 344 participants, 238 (69.2%) achieved viral suppression during 1,823 person-months of follow-up, corresponding to an incidence rate of 13.1 per 100 person-months. The median time to suppression was 7 months (IQR, 5–12). In multivariable analysis, absence of opportunistic infection (AHR, 1.44; 95% CI, 1.06–1.96), CD4 counts of 200–350 cells/mm³ (AHR, 1.75; 95% CI, 1.24–2.45) and > 350 cells/mm³ (AHR, 1.53; 95% CI, 1.02–2.28), and non-substance use (AHR, 1.54; 95% CI, 1.19–1.99) were associated with a higher rate of viral suppression. Compared with TDF+3TC + DTG, TDF+3TC + NVP and AZT+3TC + EFV were associated with lower rates of suppression. Longer ART duration was progressively associated with a lower rate of suppression compared with < 12 months of ART. Among adults receiving ART with a viral load ≥1,000 copies/mL, 69.2% achieved subsequent viral suppression. Viral suppression was associated with CD4 count, ART regimen, opportunistic infection, ART duration, and substance use. Strengthening clinical monitoring, optimizing ART, and addressing clinical and behavioural barriers may improve viral suppression in this population.