Cost analysis of once-daily ISMN versus twice-daily ISMN or transdermal patch for nitrate prophylaxis

Objective: To compare the costs and outcomes of treating exercise-induced angina with once- or twice-daily isosorbide mononitrate (ISMN) or transdermal patch. Method: A decision-analytic model was designed based on published literature showing compliance and increasing symptoms and estimates from physicians on treatment patterns and worsening symptoms. Results: Data show that patients are more compliant with once-daily ISMN (Imdur®, Astra Hassle, Molndal, Sweden) and patch regimens than with twice-daily dose. Based upon the assumption that more compliant patients are better controlled, the model found that fewer medical care resources were consumed by patients treated with the once-daily and the patch regimens. The unit cost of the twice-daily ISMN regimen is 40% of the unit cost of the once-daily. Annual costs of treating an exercise-induced angina patient are £248 for Imdur® compared to £250 for the twice-daily ISMN and £299 for the transdermal patch. Conclusion: Unit prices alone are not good indicators for estimating medical management costs.