Cost of switching darunavir+ritonavir (DRV+RTV) to lopinavir/ritonavir (LPV/r) in HIV‐1‐infected treatment‐naïve women of child‐bearing age (WOCBA)

Abstract

Guidelines consider LPV/r a preferred protease inhibitor for use during pregnancy. When an HIV‐infected woman receiving DRV+RTV becomes pregnant, a switch to LPV/r may be warranted. The budget implications of proactively initiating LPV/r versus initiating DRV+RTV and then switching has not been examined. A cost‐minimization analysis was performed from the US healthcare perspective for HIV‐1‐infected, treatment‐naïve WOCBA comparing: initiating LPV/r in all patients versus initiating DRV+RTV and switching to LPV/r when pregnant. A discrete event simulation was employed to represent antiretroviral (ARV) therapy management. Healthcare utilization and clinical trial data [ 1 ] were used to model pregnancy rates [ 2 ], ARV regimen switch rates, and impact of treatment as a function of CD4‐cell count and viral load, adherence, treatment response, acquired resistance mutations, and ensuing treatment changes. Five‐ and 10‐year costs incurred due to ARV therapy, clinician visits and management of AIDS‐related, non‐AIDS related, and cardiovascular events were estimated. Base‐case analysis assumptions: switching to LPV/r can occur only once at first pregnancy, 30% of WOBCA switch to LPV/r circa time of pregnancy, and women's adherence to medication improves by 15% when becoming pregnant. Sensitivity analyses varied the rate of switching to LPV/r at time of pregnancy, pregnancy rates, adherence improvement, and healthcare costs. Daily drug cost of LPV/r + TDF/FTC was $56.59 while DRV+RTV+TDF/FTC was $73.89. Costs were discounted at 3% per annum. Survival was similar in both groups. Five‐ and 10‐year total healthcare costs of ARV‐naïve HIV‐positive WOCBA who initiate LPV/r were $108,200 and $192,600 per patient, respectively, compared to $132,200 and $234,400 when women initiated DRV+RTV and then 30% switched to LPV/r. Initiating with LPV/r resulted in 5‐ and 10‐year savings of $24,000 and $41,800 per patient, respectively. If 100% of patients who initiated with DRV+RTV switched to LPV/r upon pregnancy, the savings per patient were $21,300 at 5 years or $33,140 at 10 years, since a greater number of patients switch to the less expensive LPV/r. Sensitivity analyses showed that initiating with LPV/r was always cost‐saving relative to DRV+RTV. Initiating HIV‐infected, treatment‐naïve WOCBA on LPV/r was cost‐saving compared to initiating DRV+RTV. Limitations of the analysis include the uncertainty of long‐term outcomes projections driven by short‐term clinical trial endpoints.