Cost-Effectiveness of Combination Therapy for Patients With Systemic Sclerosis-Related Pulmonary Arterial Hypertension.

Background To evaluate the cost-effectiveness of combination pulmonary arterial hypertension specific therapy in systemic sclerosis-related PAH. Methods and Results Health outcomes and costs were captured through data linkage. Health utility was derived from Medical Outcomes Study Short Form-36 scores. A probabilistic discrete-time model was developed to simulate lifetime changes in costs and health utility. Mortality was predicted using a Gompertz parametric survival model. For both treatment arms, the simulations were started using the same cohort of 10 000 patients. Probabilistic sensitivity analysis was performed using the Monte Carlo simulation with 1000 sets of sampled parameter values. Of 143 patients with systemic sclerosis-related pulmonary arterial hypertension, 89 were on monotherapy and 54 on combination therapy. Mean simulated costs per patient per year in monotherapy and combination therapy groups were AU$23 411 (US$16 080) and AU$29 129 (US$19 982), respectively. Mean life years and quality-adjusted life years from pulmonary arterial hypertension diagnosis to death of patients receiving monotherapy were 7.1 and 3.0, respectively, and of those receiving combination therapy were 9.2 and 3.9, respectively. Incremental costs per life year and quality-adjusted life year gained of combination therapy compared with monotherapy were AU$47 989 (US$32 920) and AU$113 823 (US$78 082), respectively. At a willingness-to-pay threshold of AU$102 000 (US$69 972) per life year gained, and of AU$177 222 (US$121 574) per quality-adjusted life year gained, the probability of combination therapy being cost-effective was 0.95. Conclusions The incremental cost per quality-adjusted life year gained of combination therapy compared with monotherapy was substantial in the base case analysis. Given the fatal prognosis of systemic sclerosis-related pulmonary arterial hypertension and the incremental cost per life year of AU$47 989 (US$32 920), combination therapy could be considered cost-effective in systemic sclerosis-related pulmonary arterial hypertension.