Value-based Pricing for Rifaximin Increases Access of Patients With Irritable Bowel Syndrome With Diarrhea to Therapy

Abstract

Increasing drug prices lead to payer coverage restrictions, which limit access to therapy. We assessed the cost effectiveness of rifaximin in management of patients with irritable bowel syndrome with diarrhea (IBS-D) under common payer coverage restrictions and determined the maximum price at which rifaximin would be cost effective using contemporary cost-effectiveness thresholds. A decision analytic model was constructed to evaluate quality of life, cost, and cost effectiveness of rifaximin for patients with IBS-D and complete noncoverage (insurer pays none of the drug cost), unrestricted access (insurer pays 100% of the drug cost), and formulary-restricted access (insurer pays 100% of the drug cost after for patients failed by initial therapy). The maximum cost-effective drug price was determined for each level of drug coverage using threshold analysis adjusted for willingness to pay thresholds from $50,000 to $150,000 per quality-adjusted life year (QALY). Analysis was performed from a payer perspective with a 1-year time horizon. Unrestricted and formulary-restricted access were more effective than complete non-coverage, resulting in additional 0.03 and 0.05 QALYs gained over noncoverage. However, unrestricted and formulary-restricted coverage were more expensive. At current drug prices, unrestricted or formulary-restricted coverage would cost an additional $1,207,136 or $171,850/QALY gained, compared to complete non-coverage. A 12% to 62% price reduction ($18.46 to $26.34/pill) for formulary-restricted access and 84% to 88% price reduction ($3.53 to $4.71/pill) for unrestricted access would be needed for rifaximin to be a cost-effective treatment strategy. Rifaximin retreatment intervals, response rates, and adverse events were important factors in sensitivity analysis. Using a decision analytic model, we show that payer coverage for rifaximin for patients with IBS-D exceeds generally accepted cost-effectiveness thresholds at current drug prices. Improved payer coverage could be justified using value-based pricing methods.