Patterns and predictors of statin use after coronary artery bypass graft surgery

Objectives: The benefits of statin therapy for patients with coronary artery disease have been well documented, including those occurring after coronary artery bypass graft surgery. The purposes of this study were to assess statin prescription rates in patients who have undergone coronary artery bypass graft surgery and to identify the determinants of postoperative statin administration. Methods: A retrospective cohort of 9284 Medicare patients aged 65 years or older who underwent coronary artery bypass graft surgery (1995-2004) was assembled by using linked hospital and pharmacy claims data. Rates of statin use after hospital discharge were calculated, and predictors of postoperative statin use were identified by using generalized estimating equations. Results: Overall, 35.9% of patients received statins within 90 days of coronary artery bypass graft surgery discharge. Use of statins within 90 days after coronary artery bypass graft surgery steadily improved during the study period, from 13.1% in 1995 to 60.9% in 2004. Patient factors independently associated with an increase in postoperative statin therapy included preoperative statin use (odds ratio, 7.69), later year of operation (odds ratio, 1.22 per additional year), and additional postoperative medications (odds ratio, 1.16 per additional medication). Factors independently associated with a decrease in postoperative statin therapy included peripheral vascular disease (odds ratio, 0.60), diabetes mellitus (odds ratio, 0.67), stroke (odds ratio, 0.77), and older age (odds ratio, 0.96 per additional year). Surgeon and hospital characteristics were not independently associated with postoperative statin use. Conclusions: Statins are considerably underused after coronary artery bypass graft surgery, although recent prescription rates are increasing. Patterns of use do not appear to correlate with coronary artery disease risk. These findings highlight the need for targeted quality improvement initiatives to increase the rate of statin administration to this at-risk population.