Cardiovascular outcomes among patients newly initiating atorvastatin or simvastatin therapy: a large database analysis of managed care plans in the United States.

BACKGROUND: While the results of randomized clinical trials have indicated that statins improve outcomes in patients without cardiovascular disease (CVD), it remains uncertain whether there are differences in efficacy between statins, particularly in clinical practice, where the public health implications could be substantial.
OBJECTIVE: We assessed cardiovascular (CV) outcomes among primary-prevention patients newly initiating therapy with atorvastatin or simvastatin.
METHODS: Using claims data from 92 US managed care plans, we identified new statin users without CVD who initiated atorvastatin (10 or 20 mg) or simvastatin (20 or 40 mg) from January 2003 to September 2005 and were continuously enrolled in a covered plan for > or = 12 months before and > or = 1 month after the initiation of statin therapy. The main outcome was the time to the first CV event (hospitalization related to myocardial infarction, angina, or coronary artery disease; stroke; amaurosis fugax; transient ischemic attack; peripheral or central nervous system vascular disease; or revascularization). Persistence with treatment was calculated in terms of the number of days during follow-up that a patient remained on statin treatment, starting from the date of the first prescription fill to the end of the study or the date at which therapy was discontinued.
RESULTS: A total of 168,973 patients initiating atorvastatin (mean dose, 13.5 mg) and 50,658 patients initiating simvastatin (mean dose, 28.5 mg) were followed for a median of 1.5 years. Atorvastatin patients were significantly more persistent with treatment than simvastatin patients (median treatment duration, 158 vs 124 days, respectively; P < 0.001). After adjustment for age, sex, type of health plan, payer type, geographic region, calendar year of statin initiation, physician specialty, comorbidities, concomitant therapies, and total direct health care costs in the year before statin initiation, use of atorvastatin was associated with significantly fewer CV events compared with use of simvastatin (hazard ratio = 0.88; 95% CI, 0.83-0.93; P < 0.001).
CONCLUSIONS: In these patients without CVD, atorvastatin 10 or 20 mg was associated with a significantly lower risk of CV events compared with simvastatin 20 or 40 mg. Further studies are required to determine whether differences in persistence, achieved low-density lipoprotein cholesterol levels, or other factors contribute to these differences in outcomes.