Measuring adherence trends among patients taking a 3-hydroxy-3-methylglutaryl-coenzyme-A (HMG-CoA) reductase inhibitor

Abstract

Specific Aims: There are three specific aims for this project. 1) Determine if PDC rates in patients taking a statin medication differ between male and female patients. 2) Determine if PDC rates in patients taking a statin medication differ between patients with only one chronic condition versus those with more than one chronic condition. 3) Determine if PDC rates in patients taking a statin medication differ between type of statin therapy. Our working hypothesis for all three hypotheses is that there is a statistically significant difference between groups. Purpose: How many of your patients are not adherent to their statin regimen? Patients who are nonadherent to their 3-hydroxy-3-methylglutaryl-coenzyme-A reductase inhibitor therapy (statin) are at increased risk of uncontrolled cholesterol levels, cardiovascular events, and mortality. As patients are diagnosed with more disease states they are likely to be prescribed more medications for treatment. The study objective was to evaluate how the number of comorbidities affect medication adherence, measured via the Proportion of Days Covered. Additional analyses were conducted for adherence based on patient gender and by type of HMG-CoA reductase inhibitor. Methods: Data was originally collected by SinfoníaRx, a medication management technology and service company, as part of an internal quality improvement project. For this retrospective review, the data were deidentified by SinfoníaRx staff prior to providing it to the researchers. Variables in the de-identified data set included patient age, patient gender, Proportion of Days Covered, the number of chronic conditions for each patient, and the specific 3-hydroxy-3-methylglutaryl-coenzyme A reductase drug the patient was taking. Separate data sets were then created from the original data by filtering patients by gender, number of comorbidities, and specific drug. The gender analysis consisted of two groups (male and female) and a t-test was performed to analyze the average Proportion of Days Covered between the groups. An analysis of variance was performed to analyze the average Proportion of Days Covered. A Bonferonni post-hoc analysis was performed to measure significance between the groups. Results: A total of 55,345 patients were included in the analysis. Patients with multiple comorbidities were significantly more adherent according to their average Proportion of Days Covered (expressed as a percent) as follows: 0- (58.8%, P = <0.01), 1- (63.4%, P = <0.01), and 2-4- comorbidities (68.1%, P = <0.01). Men’s adherence rates were 68.13% and women’s adherent rates were 67.65%. Atorvastatin and the ezetimibe/simvastatin combination medications had significantly better adherence when compared individually to the other drugs included in the analysis. Conclusion: This study suggests that patients with more chronic conditions were more adherent to their medications than those with fewer or no chronic conditions. However, even the most adherent patients in this study still had Proportion of Days Covered values well below the recommended threshold. Future research is warranted to facilitate designing adherence program materials to help patients with fewer chronic conditions improve adherence to prescribed regimens.