Primary Prophylaxis Against Pneumocystis jiroveci Pneumonia Is Cost-effective in Crohnʼs Disease Patients on Immunosuppresive Medications

Abstract

Purpose: There have been increasing reports of Pneumocystis jiroveci pneumonia (PJP) in inflammatory bowel disease (IBD) patients. The risk for PJP appears highest in Crohn's disease (CD) patients on immunosuppressive medications. We sought to investigate the cost-effectiveness of primary prophylaxis against PJP in patients with Crohn's disease. Methods: A mathematical microsimulation model was used for this analysis. We simulated a virtual cohort of 100,000 male and female CD patients and compared estimated outcomes in the presence and absence of PJP prophylaxis. CD severity, adverse drug reactions (ADR), glucose-6-phosphate dehydrogenase status, and direct costs associated with PJP prophylaxis and treatment were accounted for in the model. Two strategies were compared: 1.) Primary prophylaxis for all CD patients on at least one immunosuppressive agent, and 2.) No PJP prophylaxis for CD patients (base case). Results: Without PJP prophylaxis, the cohort gained an average 34.7 quality-adjusted life years after CD diagnosis, with an average lifetime cost of about $300,000 at a 3.5% discount rate. With PJP prophylaxis, the average quality-adjusted life years gained was 37.6, with average lifetime cost of $320,000 at the same discount rate. The estimated incremental cost effectiveness ratio was $18,550 per quality-adjusted life year gained. PJP prophylaxis led to an estimated 70-80% reduction in the lifetime risk of PJP, from 0.7% in the “no PJP prophylaxis” strategy to 0.1% in the “PJP prophylaxis” strategy. This resulted in a number needed to treat between 167 and 334 to prevent one case of PJP over the lifetime of the cohort. Conclusion: At a willingness-to-pay threshold of $50,000, initiating primary prophylaxis for CD patients on immunosuppressive agents appears to be cost-effective. This is largely driven by the low cost of prophylaxis, tolerable ADR profile of prophylactic agents, and high mortality of PJP. Additional cost-effectiveness studies will be needed to validate these findings.