Shah ED¹, Saini SD², Chey WD². Clin Gastroenterol Hepatol. 2019 Mar 1. pii: S1542-3565(19)30245-9. doi: 10.1016/j.cgh.2019.02.039. [Epub ahead of print]

Author information

1 Division of Gastroenterology and Hepatology, Dartmouth-Hitchcock Medical Center, Lebanon, NH; Division of Gastroenterology, Michigan Medicine, Ann Arbor, MI. Electronic address: eric.d.shah@hitchcock.org.

2 Division of Gastroenterology, Michigan Medicine, Ann Arbor, MI.

Abstract

BACKGROUND & AIMS: Increasing drug prices lead to payer coverage restrictions, which limit 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.

METHODS: 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.

RESULTS: 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 $171,850 or $1,207,136/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.

CONCLUSION: 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.