Treatment Outcomes After Switching to Second-Line Anti-Retroviral Therapy: Results From the Thai National Treatment Program

This study aimed to assess second-line antiretroviral therapy (ART) outcomes in a National HIV Treatment program. People living with HIV aged ≥18 years initiating first-line ART who switched to second-line protease inhibitor-based regimens from January 2008 to May 2019, with a minimum of 1-year follow-up were studied. The primary outcome was second-line treatment failure (two consecutive virological failure episodes (viral load ≥1000 copies/mL)). Of 318,506 PLH initiating ART, 29,015 (9.1%) switched to second-line regimens after a median (IQR) ART duration of 1.63 (0.60-3.59) years. Lost to follow-up (LTFU) occurred in 5316 (18.3%) of whom 1376 (5%) remained LTFU and alive; 4606 (15.9%) died. Cumulative second-line failure incidence was 9.8% at 6 years, more common in females, younger PLH those with lower switch CD4 cell counts. Multidisciplinary, innovative support systems are needed to improve second-line treatment outcomes, particularly those relating to modifiable risk factors.