Pfizer announced the results of an observational study that showed patients taking Lipitor (atorvastatin calcium) had a significant 13 per cent reduction in the relative risk of experiencing a cardiovascular event compared with patients taking simvastatin (Zocor) therapy. The patients in this study did not have evident cardiovascular disease and were newly initiated on either treatment. This study was performed in conjunction with HealthCore, WellPoint's health outcomes research subsidiary. Results of this study, from one of the largest US managed care claims databases with more than 219,000 adult patients, were published in the December issue of Mayo Clinic Proceedings.
The study examined data for patients 18-64 years old who had no prior statin use or medical claims related to cardiovascular disease in the 12 months preceding initiation of statin therapy. The average doses in the study were 29 mg of simvastatin and 17 mg of Lipitor.
"Observational data such as this, which reflect the use of medicines in real-world clinical practice rather than in a controlled trial setting, may help healthcare providers and managed care companies improve clinical outcomes for patients," said Terry A Jacobson, professor of Medicine, Emory University, and director of the Office of Health Promotion and Disease Prevention, Grady Health Systems. "The data suggests that statins with greater potency may result in greater cardiovascular risk reductions. Economic assessments should be performed to determine the potential impact of this study on cost of care to patients."
In addition to the significant reduction in the risk of overall cardiovascular events, individual event rates of secondary endpoints, first heart attack and hospitalizations for heart failure, were significantly lower for patients initiating Lipitor compared with patients initiating simvastatin. There was no significant difference between the groups for the secondary endpoints of stroke, revascularization surgery or peripheral vascular disease.
"This latest analysis adds to the wealth of real-world data from a number of different medical database analyses that suggest that patients who are treated with Lipitor may have a reduced risk of experiencing a cardiovascular event compared with patients who use simvastatin," said Dr Michael Berelowitz, senior vice president of Pfizer's global medical division. "Findings such as these should be taken into account by those who may assume that medicines in a therapeutic class are interchangeable and provide similar outcomes."
As with all observational studies, the study is subject to certain limitations and the findings should be regarded as hypothesis generating.
This is one of the largest observational studies to date to examine cardiovascular outcomes in patients without clinically evident cardiovascular disease treated with different statins in routine clinical practice.
The retrospective analysis examined administrative claims for statin prescriptions filed between January, 2003 and December, 2005. The longer mean treatment duration of patients who took Lipitor versus simvastatin (nine and seven months, respectively) might have impacted the difference in cardiovascular event reduction.
A cardiovascular event was defined as the first inpatient or emergency room admission for heart disease, heart attack, angina (chest pain), certain heart surgeries, peripheral vascular disease, aortic aneurysm (swelling of the aorta), stroke and transient ischemic attack.
Since patients were not randomly assigned to each group, the two treatment arms were adjusted based on certain risk factors, such as age, gender and co-morbidities, and statistical adjustments were used to address residual imbalances. LDL values prior to and after treatment were only available for approximately five percent of the patients and this was not adjusted for in the analysis.
The results of this study complement the large body of evidence from multiple clinical trials demonstrating the cardiovascular benefits of Lipitor in patients without heart disease and are in alignment with findings from previously published observational studies.