Background: While randomized controlled trials (RCTs) generate informative data about clinical outcomes, by their nature they cannot provide information about drug utilization and factors influencing prescribing decisions. In the secondary prevention of patients with cardiac events, lipid lowering therapy with statins and other agents, such as cholesterol absorption inhibitors (CAI, e.g. ezetimibe) plays a pivotal role and is often initiated or modified in rehabilitation centres. The aims of the present study were to analyse factors that influence the prescribing decisions of physicians, and to investigate success rates of lipid lowering therapy with ezetimibe after adjustment for covariates.
Methods: Ninety-three rehabilitation centres throughout Germany documented a total of 17029 patients in cardiac rehabilitation, of which 6976 (41.6%) were prescribed a CAI. A logistic regression model with forward selection based on 31 potential regressors for ezetimibe prescription (demographics, diagnosis, risk factors etc.) was used to construct a propensity score, which reflects the inclination of physicians to prescribe CAI. This score was subsequently used for bias reduction in the comparison of co-medications and success rates.
Results: Nineteen variables were associated with ezetimibe prescriptions, the most important ones being total cholesterol, level of education, unstable angina pectoris and arterial hypertension. Ezetimibe was more frequently prescribed together with simvastatin and pravastatin than with other statins, and frequently together with aspirin or beta blockers, respectively. After adjustment for baseline lipid values and covariates, the probability of target level achievement appears to be substantially higher for patients on ezetimibe than for those without ezetimibe.
Conclusions: Other factors than conventional risk factors contribute to the CAI prescription habits of physicians. Additional lipid level reductions due to ezetimibe are seen in routine health care corresponding to findings from randomized studies.