CE2 - Cost-Effectiveness of An Adherence-Enhancing Intervention for Patients with Gout Based on Real-World Data

Abstract

Medication non-adherence influences outcomes of therapies for chronic diseases. Allopurinol is a cornerstone therapy for patients with gout, however, non-adherence to allopurinol is prevalent in Singapore and limits its effectiveness. Between 2008–2010, an adherence-enhancing programme including health education, patient empowerment, and self-management training was implemented at the rheumatology division of a public tertiary hospital. The cost-effectiveness of this intervention has not been fully evaluated. As healthcare resources are finite, the value of investing in adherence-enhancing interventions should be ascertained. This study aims to evaluate the cost-effectiveness of this adherence-enhancing programme so as to inform optimal resource allocation toward better gout management. Adopting a real-world data approach, we utilized patient clinical, pharmacy, and financial records generated in their course of routine hospital care. 111 intervention and 198 control patients were identified in a standing database and matched on nine risk factors through propensity score matching. Cost and utility data were followed through one to two years for 106 matched results. A decision tree was developed with TreeAge Software using a societal perspective. Deterministic and probabilistic sensitivity analyses were performed to assess parameter uncertainty. At an assumed willingness-to-pay threshold of 70,000 SGD (equivalent to 50,000 USD) per quality-adjusted life year (QALY), the intervention had an 85% probability of being cost-effective compared to routine care. The incremental cost-effectiveness ratio (ICER) was 18,121 SGD per QALY for the base case and ranged from 5,829 to 30,413 SGD per QALY in sensitivity analyses. The model driver is inpatient cost which was the least robust based on Tornado analysis. The intervention is cost-effective in the short-term, although its long-term cost-effectiveness remains to be evaluated.