Virologic Outcomes of Predominantly Tenofovir-Based First-Line Antiretroviral Therapy Among Treatment-Naïve HIV Patients in Davao City, Philippines

Background/Objectives: Tenofovir disoproxil fumarate (TDF)-containing regimens remain the cornerstone of first-line antiretroviral therapy (ART) in many low- and middle-income countries. However, concerns regarding treatment failure and antiretroviral resistance highlight the need to evaluate the effectiveness of treatments under routine clinical conditions. This study evaluated the virologic outcomes of treatment-naïve individuals living with HIV who received predominantly TDF-based first-line ART in Davao City, Philippines. Methods: A retrospective observational study was conducted among treatment-naïve HIV patients who initiated ART between 2016 and 2020. Demographic and clinical characteristics, ART regimens, HIV surveillance stage classifications, and viral load results were extracted from routinely collected medical records. Virologic suppression was defined as an HIV RNA viral load of <1000 copies/mL and virologic failure as ≥1000 copies/mL. The availability of viral load monitoring and the interval between ART initiation and the latest viral load measurement were also evaluated. Results: A total of 494 treatment-naïve patients with HIV were included. Most patients were male (97.8%) and received TDF-containing regimens (99.0%), predominantly TDF + 3TC + EFV (95.1%). Viral load results eligible for outcompe analysis were available for 174 (35.2%) patients. Among these patients, 165 achieved virologic suppression, corresponding to a suppression rate of 94.8% (95% CI: 90.5–97.3), whereas virologic failure was observed in nine patients (5.2%; 95p% CI: 2.7–9.5). Viral load availability declined substantially among patients initiating ART in recent years, reflecting shorter follow-up durations and fewer opportunities for routine viral load monitoring. High levels of virologic suppression were observed across the demographic and clinical subgroups. Conclusions: Predominantly TDF-based first-line ART demonstrated high virologic effectiveness among treatment-naïve HIV patients with evaluable viral load measurements, with nearly 95% of patients achieving virologic suppression. However, incomplete viral load monitoring, particularly among patients initiating ART in later years, limits the evaluation of treatment outcomes at the program level. Strengthening routine viral load monitoring and long-term follow-up will improve the future real-world evaluation of ART effectiveness.