Statins are HMG-CoA reductase inhibitors, a class of lipid-lowering drugs used to reduce illness and mortality in patients who are at a high risk of cardiovascular disease (CVD). However, the effects of long-term adherence to statins remain controversial. This study aims to examine the association between statin adherence and mortality in patients with atherosclerotic cardiovascular disease (ACD).

This retrospective cohort study included a total of 347,104 adults aged 21-85 years who confirmed ACD and were undergoing statin treatment. Statin adherence was defined using medication possession ratio (MPR), and adherence levels were categorized as MPR less than 50%, 50-69%, 70-89%, and 90% or more. The primary outcome of the study was all-cause mortality.

The findings suggested that patients taking moderate-intensity statin treatment were more adherent than patients taking high-intensity statin therapy. Younger are older patients were less likely to be adherent compared with adults aged 65-74 years. During a mean follow up of 2.9 years, a total of 85,930 deaths (24.8%) were reported. Patients with an MPR less than 50% had a hazard ratio of 1.30, followed by 1.21 for MPR 50-69%, and 1.08 for MPR 70-89%.

The research concluded that low adherence to statins, which was common in younger and older patients, was associated with a higher risk of mortality.