Abstract
BACKGROUND: Suboptimal adherence to aspirin therapy for secondary prevention of cardiovascular (CV) events is an important public health problem. Prior studies have demonstrated non-adherent patients are at higher risk of experiencing CV events. OBJECTIVES: This study aimed to estimate the clinical and economic outcomes of aspirin non-adherence in patients with a prior primary CV event. METHODS: We developed a Markov model to estimate the cost-effectiveness of aspirin adherence from a generic US managed care payer perspective over a 5-year time horizon. Costs, utilities and rates of aspirin adherence, CV events and adverse events were gathered from published literature to populate the model. Outcomes were quality-adjusted life years (QALYs), costs (US$) and incremental cost-effectiveness ratios (ICERs). We applied the model separately to a population without type II diabetes as a comorbidity (non-diabetic model) and a population with type II diabetes (type II diabetes model). A one-way sensitivity analysis was performed to assess the model uncertainty. RESULTS: The base case showed adherent patients lived 0.25 and 0.36 QALYs longer than non-adherent patients in the non-diabetic model and type II diabetes model, respectively. Adherence to aspirin had an ICER of US$25/QALY in the non-diabetic population, while it saved US$297 per patient over a 5-year period in the type II diabetes population. One-way sensitivity analysis showed the models were most sensitive to rates of non-fatal events in non-adherent patients. CONCLUSION: This study suggests aspirin adherence may improve QALYs for patients with a prior primary CV event. Further, it may decrease costs in patients with type II diabetes. While additional research is needed to validate these results, payers may wish to increase strategies to promote adherence in order to improve population health. TRIAL REGISTRATION: Not applicable.