Pharmaceutical use and costs in patients with coronary artery disease, using Australian observational data

OBJECTIVES: We aimed to estimate the annual pharmaceutical costs for patients with stable coronary artery disease, using Australian administrative data, comparing patients who had undergone interventional treatment with those had not. We also aimed to compare the duration of dual antiplatelet therapy (DAPT) prescription in the real-world, with recommended guidelines. DESIGN: An observational study using administrative data. PARTICIPANTS: We used data from the QSkin study, a population-based prospective study assessing skin cancer risk. Participants were invited from the Queensland population, not based on perceived skin cancer risk, and had consented to future use of their data for approved research projects. MAIN OUTCOME MEASURES: We calculated 12-month costs of pharmaceutical therapy for coronary artery disease for patients in each of three clinically relevant groups: medical therapy only, following coronary stent implantation and following coronary artery bypass graft surgery. We measured the duration of DAPT following stent implantation and total duration of DAPT, where it was prescribed, in the medical therapy only group. RESULTS: Estimated mean annual pharmaceutical costs were highest in the stent group at AUD$1920, compared with AUD$1481 in the medical therapy group, and AUD$881 in the coronary artery bypass group. There were similar rates of prescriptions of symptom relief drugs following stent insertion, compared with the medical therapy only group. The median duration of DAPT in the stent group was 16, and 31 months in the medical therapy group. CONCLUSIONS: Our results suggest that despite the common expectation that the burden of medical therapy is reduced following coronary stent insertion for stable coronary artery disease, this does not occur in practice. Many patients also appear to continue DAPT longer than guidelines recommend, which may put them at unnecessarily elevated risk of bleeding events.