Objective: In US treatment guidelines, efavirenz (EFV) is the preferred non-nucleoside reverse transcriptase inhibitor (NNRTI) for first-line HIV treatment. In the ECHO and THRIVE trials comparing EFV with another NNRTI, rilpivirine (RPV), both medications had similar virologic suppression rates at 96-weeks; however, RPV had higher rates of virologic failure and drug resistance and lower rates of discontinuation due to adverse events. This study compared the cost-effectiveness of EFV to RPV in first-line HIV treatment in the US.
Methods: A Markov model with 14 health states was constructed to estimate 10-year costs and clinical outcomes from a US payer perspective for antiretroviral naïve HIV patients initiating EFV or RPV. First-line efficacy data came from 96-week results of the ECHO and THRIVE trials, which compared EFV and RPV, both in combination with two nucleos(t)ide reverse transcriptase inhibitors. Other clinical inputs, mortality rates, and costs (2011 US$) came from published sources. Subsequent therapy lines (second, third, non-suppressive) were based on US treatment guidelines and common to both treatment arms. Robustness of study results was assessed in sensitivity analyses varying model inputs by ±25%. Potential limitations of the model center on the ability of any model to capture the clinical complexity of HIV treatment.
Results: In the base case, 10-year costs were lower for EFV compared to RPV ($214,031 vs $222,090). Life expectancy (8.44 years) and years without AIDS (8.40 years) were equal; years in virologic suppression were similar (EFV = 7.87 years, RPV = 7.86 years). EFV had modest cost savings compared to RPV in terms of incremental cost-effectiveness per life-year gained, life-year gained in viral suppression, and life-year gained without AIDS. In sensitivity analyses, EFV remained cost-saving compared to RPV in over 90% of scenarios, demonstrating the robustness of study results.
Conclusions: EFV was predicted to be modestly cost-saving compared with RPV over 10 years in US patients initiating first-line HIV treatment. Sensitivity analyses suggest that results may hold across multiple settings.