"It is important for patients to remain on their medications, especially those with chronic conditions such as high cholesterol, which when uncontrolled may increase a patientâs risk for heart attacks and strokes," said Dr. JoAnne M. Foody, study lead author, associate professor of medicine at Harvard Medical School and director of the Cardiovascular Wellness Center at Brigham and Women's/Faulkner Hospitals, Boston. "In patients who take statins to manage their cholesterol levels, poor persistence has been linked with an increase in heart attacks and strokes in addition to higher healthcare costs."
According to the results:
- Of patients without prior cardiovascular events (n=175,322), those treated with Lipitor were a significant 15 percent less likely to discontinue therapy in the first year than those treated with simvastatin.
- Of patients who had at least one prior cardiovascular event (n=11,331), those treated with Lipitor were a significant 22 percent less likely to discontinue therapy than those treated with simvastatin.
A subanalysis examined the persistence rates of patients aged 65 years and older, who are at a higher risk for cardiovascular events and are known to have lower persistence rates than younger patients. In this retrospective database analysis, persistence rates were defined as the number of days a patient remained on treatment in the first year following medication start date.
According to the results:
- Overall, persistence was worse in elderly patients than in younger patients for both statins, but the relative difference between Lipitor and simvastatin users was similar to that of the overall patient population.
- Elderly patients without prior cardiovascular events (n=8,278) treated with Lipitor were a significant 22 percent less likely to discontinue therapy than those treated with simvastatin.
- Elderly patients with at least one prior cardiovascular event (n=980) treated with Lipitor were a significant 26 percent less likely to discontinue therapy than those treated with simvastatin.
"Today, physicians face increasing pressure to switch from established statin therapy to generics, based on the perception that all statins are equivalent," said Dr. Rochelle Chaiken, vice president of Pfizer's global cardiovascular and metabolic medical team. "This observational study provides important real-world insights into statin usage patterns and suggests that the choice of statin may have a significant effect on whether a patient remains on their prescribed medication. When choosing a medication, it is critical for clinicians to consider all of the factors that may influence the long-term effectiveness of therapy."
About the study
This Pfizer-funded study was a retrospective analysis using anonymous patient-level health plan data from IMS Health, a healthcare information and consulting company. At the time of the analysis, the IMS database included fully adjudicated medical and pharmacy claims for 52 million individual patients from 92 health plans across the U.S. A total of 186,653 primary and secondary prevention patients with at least one complete year of follow up were included in this study; 136,652 patients received atorvastatin, and 50,001 received simvastatin.
As with all observational studies, this study has some limitations. For example, the reasons for medication discontinuation were not tracked in the database. Although the analysis accounted for a range of important variables, differences in persistence after adjusting for all known baseline imbalances could still be due in part to unmeasured confounding factors such as differences in effectiveness, side-effects, cost or other attributes of the statins. Further studies are required to explore these factors.
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