Impact of Stalin Adherence on Cardiovascular Morbidity and All-Cause Mortality in the Primary Prevention of Cardiovascular Disease: A Population-Based Cohort Study in Finland

Objectives: To assess the extent to which adherence to statins is associated with the incidence of cardiovascular (CV) events and all cause mortality in the primary prevention of CV diseases and whether different analytical approaches influence the observed associations. Methods: This population based cohort study used data from Finnish registers. The cohort included 97,575 new statin users aged 45 to 75 years in 2001 to 2004 with no CV diseases at baseline. Exposure was defined as adherence to statins (proportion of days covered [PDC]). The primary outcome was any CV event or death during a 3-year follow-up. Different analytical approaches, including multivariable-adjusted Cox regression, inverse probability weighting with time varying adherence, and propensity score calibration, were used. Results: During the first year of follow-up, 53% displayed good (PDC >= 80%), 26% had intermediate (PDC 40%-79%), and 21% exhibited poor (PDC <40%) adherence. After adjustment for sociodemographic and clinical covariates, a 25% relative risk reduction (hazard ratio [HR] 0.75; 95% confidence interval [CI] 0.71-0.79) was observed in the rate of any CV event or death among good versus poor adherers. Good adherers also had a lower incidence than poor adherers of acute coronary syndrome (HR 0.56; 95% CI 0.49-0.65) and acute cerebrovascular disease events (HR 0.67; 95% CI 0.60-0.76). The different analytical approaches achieved comparable results for all the outcomes. Conclusions: The incidence of CV events and mortality was higher in poor versus good adherers. Different analytical methods that took into account changes in adherence and confounding at baseline did not appreciably affect the results.