Academic journal article Applied Health Economics and Health Policy

Cost-Efficacy Analysis of the MONET Trial Using UK Antiretroviral Drug Prices

Academic journal article Applied Health Economics and Health Policy

Cost-Efficacy Analysis of the MONET Trial Using UK Antiretroviral Drug Prices

Article excerpt


There is increasing pressure to lower the cost of treating people with HIV infection in the UK, for three main reasons. First, new treatment guidelines recommend earlier initiation of treatment, with CD4 counts of 350-500 cells/μL[1-4] - this increases the number of patients eligible for treatment in the UK. Second, with antiretroviral treatment improving survival, but infection rates remaining constant,[4,5] there is an increasing number of patients remaining on antiretroviral treatment every year in the UK. Third, with economic pressures on the UK NHS, there is little additional funding to cover the increasing number of patients requiring treatment. Strategies to lower costs of HIV treatment and care are clearly necessary.

In the MONET (MONotherapy in Europe with TMC114) trial,[6] 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 darunavir/ritonavir (DRV/r) 800/100 mg once daily, either as monotherapy (n = 127) or with two NRTIs (n = 129). In the primary efficacy analysis, HIV RNA <50 copies/mL by week 48 (per protocol) was 86.2% versus 87.8% in the DRV/r and control arms, respectively; by the 'switch included analysis', efficacy was 93.5% versus 95.1%, respectively. Nine patients in each arm experienced serious adverse events. No patients in either arm developed phenotypic resistance to darunavir. A parallel French study with a similar design - MONOI[7] - showed consistent results. In virologically suppressed patients, switching to DRV/r monotherapy maintained 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. Cost savings were calculated at the patient level, as was the overall budget impact at the national level.


MONET is an ongoing, 144-week, randomized, controlled, open-label phase 3b trial, with data obtained from 256 patients in 11 European countries, Russia and Israel.[6] The trial recruited patients who had HIV RNA levels <50 copies/mL on a stable triple antiretroviral regimen, for at least 24 weeks, and no history of virological failure since first starting antiretrovirals. Patients were randomized to receive DRV/r 800/100 mg once daily, either as monotherapy (monotherapy arm) or with two NRTIs (triple therapy arm). The nucleoside analogues used during the MONET trial were selected by the investigators and could be changed either at screening or during the trial.

Patients attended study visits at screening, baseline, weeks 4 and 12, and then every 12 weeks to week 96. Any patient with an HIV RNA result >50 copies/mL attended a confirmation visit within 2 weeks, for repeated testing of HIV RNA, drug resistance and plasma drug levels. If a patient had two consecutive HIV RNA levels >50 copies/mL, investigators could intensify or change antiretrovirals.

Using British National Formulary 2009 values,[8] the annual cost of antiretroviral treatment was calculated for each patient, both before and during the trial. The antiretrovirals used at the screening visit were used to calculate the cost of treatment before the trial. The sum of all antiretrovirals used during the trial was used to calculate the cost of treatment during the trial. For example, if a patient used DRV/r monotherapy for 8 months, and then intensified with nucleoside analogues, the total cost of these antiretrovirals was calculated. The cost of patient visits was calculated using UK Department of Health estimates.[9]

For the budget-impact analysis, we used an estimate of 45 000 people in the UK currently being treated for HIV infection.[5] Based on the UK Collaborative HIV Cohort (CHIC),[10] we assumed that at least 40% of these patients have HIV RNA levels <50 copies/mL on current treatment, and no history of virological failure. …

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