Cost-effectiveness of enhancing adherence to therapy with blood pressure-lowering drugs in the setting of primary cardiovascular prevention

OBJECTIVE: To estimate the cost-effectiveness of enhancing adherence to blood pressure BP)-lowering drug therapy in a large population without signs of preexisting cardiovascular (CV) disease. METHODS: A cohort of 209,650 patients aged 40 to 79 years resident in the Italian Region of Lombardia and newly treated with BP-lowering drugs during 2000 to 2001 was followed from index prescription to 2007. During the follow-up, the 10,688 patients who experienced a hospitalization for a coronary or cerebrovascular event were identified (outcome). Adherence was measured by the proportion of days covered by the therapy with BP-lowering drugs. The cost-effectiveness of enhancing adherence was measured through the incremental cost-effectiveness ratio. RESULTS: Enhancing adherence from 52% (baseline) to 60% and 80% led to a reduced rate for CV outcomes (from 85 to 83 and 77 events every 10,000 person-year, respectively) and increased the cost for drug therapy (from €1,325k to €1,507k and €1,934k every 10,000 person-year, respectively). The resulting incremental cost-effectiveness ratio decreased from €76k (95% confidence interval €74k-€77k) to €74k (95% confidence interval €72k-€75k) for each CV event avoided by enhancing adherence from baseline to 60% and 80%, respectively. CONCLUSIONS: Enhancing adherence to BP-lowering medications in the setting of primary CV prevention might offer important benefits in reducing the risk of CV outcome, but at a substantial cost.