Comparative effectiveness of atorvastatin (10 mg) versus simvastatin (20 mg) estimated cumulatively.

The analyses included the initiators between January 1998 and June 2006 in Finland; hazard ratios of a composite of cardiovascular events1 estimated cumulatively in the sequentially matched cohorts and in conventional Cox proportional hazard regression models. The follow-up was restricted to between 270 and 730 days since initiation.
HR = hazard ratio; CI = confidence interval; PS = propensity score.
1Cardiovascular events: hospitalized acute myocardial infarction (ICD-10 codes I20–I24), percutaneous coronary intervention or coronary artery bypass surgery, and stroke (I63, I64).
2Matching conducted within each of the 17 six-month periods since January 1998.
3Adjusted for all of the covariates included in the propensity scores, including the period.