Cost-efficacy analysis of the MONET trial using UK antiretroviral drug prices

In virologically suppressed patients, switching to darunavir/ritonavir (DRV/r) monotherapy maintains HIV RNA suppression, and could also lower treatment costs.

The purpose of this analysis was to calculate the potential cost savings from the use of DRV/r monotherapy in the UK.

In the MONET trial, 256 patients with HIV RNA < 50 copies/mL on current highly active antiretroviral therapy (HAART) for over 24 weeks (non-nucleoside reverse-transcriptase inhibitor [NNRTI] based [43%] or protease inhibitor [PI] based [57%]), switched to DRV/r 800/100 mg once daily, either as monotherapy (n = 127) or with two NRTIs (n = 129). The UK costs per patient with HIV RNA < 50 copies/mL at week 48 (responders) were calculated using a 'switch included' analysis to account for additional antiretrovirals taken after initial treatment failure. By this analysis, efficacy was 93.5% versus 95.1% in the DRV/r monotherapy and triple therapy arms, respectively. British National Formulary 2009 values were used.

Before the trial, the mean annual cost of antiretrovirals was £6906 for patients receiving NNRTI-based HAART, and £8348 for patients receiving PI-based HAART. During the MONET trial, the mean annual per-patient cost of antiretrovirals was £8642 in the triple therapy arm, of which 55% was from NRTIs and 45% from PIs. The mean per-patient cost in the monotherapy arm was £4126, a saving of 52% versus triple therapy. The mean cost per responder was £9085 in the triple therapy arm versus £4413 in the DRV/r monotherapy arm.

Based on the MONET results, the lower cost of DRV/r monotherapy versus triple therapy in the UK would allow more patients to be treated for fixed budgets, while maintaining HIV RNA suppression at < 50 copies/mL. If all patients meeting the inclusion criteria of the MONET trial in the UK were switched to DRV/r monotherapy, there is the potential to save up to £60 million in antiretroviral drug costs from the UK NHS budget.