Background: A single-tablet regimen (STR) has been associated with better drug adherence. However, the durability of different STRs was unknown in the real world settings. Our aim was to investigate the durability of different initial STR regimens in patients starting STR in southern Taiwan
Method: This was a retrospective study of antiretroviral-naive patients that initiated first-line antiretroviral regimens with STRs between May 2016 and December 2017. The primary endpoint was time to virological failure (defined as plasma HIV RNAs≧200 copies/mL after 24 weeks). Secondary endpoints were STR discontinuation due to toxicity/intolerance. Survival analysis was done using Kaplan–Meier and Cox regression.
Results: Two hundred and twenty-three patients were included: Over a median (IQR) of 86 (60-112) weeks, 25 patients (11%) experienced virological failure; the 1 year probability of virological failure was 11% (8/70) for Efavirenz/Emtricitabine/ Tenofovir Disoproxil Fumarate, 7% (4/54) for Emtricitabine/Rilpivirine/Tenofovir Disoproxil Fumarate and 13% (13/99) for Abacavir/Dolutegravir/Lamivudine. Fifty-six patients (25%) discontinued their STRs owing to toxicity/intolerance. When compared to Efavirenz/Emtricitabine/ Tenofovir Disoproxil Fumarate, treatment with Emtricitabine/Rilpivirine/Tenofovir Disoproxil Fumarate (AHR 8.39, CI 1.98-35.58, p=0.004) and Abacavir/Dolutegravir/Lamivudine (AHR 8.40, CI 2.39-29.54, p=0.001) were more likely to have treatment failure. However, when the risk of treatment failure was compared between two different STRs, treatment with Emtricitabine/Rilpivirine/Tenofovir Disoproxil Fumarate was not found to have higher risk of treatment failure when compared to Efavirenz/Emtricitabine/ Tenofovir Disoproxil Fumarate (log rank test p=0.116). The predictors for treatment failure included age≦30 years old (AHR 3.73, CI 1.25-11.17, p=0.018), switch between different STR (AHR 2.3, CI 1.18-4.50, p=0.001) and free of active syphilis infection (AHR 0.24, CI 0.08-0.73, p=0.012). The risk factor for treatment discontinuation included younger age≦30 years old (AHR 3.82, CI 1.21-12.37, p=0.023), treatment with Efavirenz/Emtricitabine/ Tenofovir Disoproxil Fumarate (AHR 8.65 , CI 2.64-28.39 , p<0.001) and free of active syphilis infection (AHR0.16, CI 0.04-0.62, p=0.006).
Conclusion: Younger age was associated with treatment failure and drug discontinuation. Active syphilis infection s/p treatment was associated with free from treatment failure and discontinuation. This probably driven by the more frequently sexual health education and counseling when patients had syphilis infection. The STR durability was dependent on the drug toxicity/intolerance, age and syphilis infection