Combined Effects of Statin Medication Adherence and Fine Particulate Air Pollution on Cardiovascular Disease Among Older Adults.

Background: Emerging research suggests the potential combined effects of statin medication and fine particulate matter exposure on cardiovascular disease (CVD) risk among older adults. These findings underscore the need for further detailed investigations. This cohort study aims to examine the combined effects of adherence to statins and particulate matter with aerodynamic diameter ≤2.5 μm (PM2.5) exposure on CVD among older adults in South Korea.

Methods: This nationwide study included 791 244 individuals aged 65 years or older diagnosed with dyslipidemia. Statin medication adherence was estimated using the medication possession ratio (MPR) over a 2-year period. Fine particulate matter levels were measured based on participants' residential locations. The primary outcome was CVD, defined as a diagnosis requiring at least 2 days of hospitalization. Multivariable Cox proportional hazard models were performed to assess the combined effects of statin MPR and PM2.5 exposure on CVD risk.

Results: Intermediate-to-high statin adherence (MPR ≥0.5) was associated with a reduced risk of CVD, regardless of PM2.5 concentrations. Individuals with the lowest statin adherence (MPR <0.5) and the highest PM2.5 concentrations had an elevated risk of CVD (adjusted hazard ratio, 1.05; 95% confidence interval, 1.02-1.07). Conversely, individuals with the highest statin adherence (MPR ≥0.8) and the highest PM2.5 concentrations showed a lower risk of CVD (adjusted hazard ratio, 0.88; 95% confidence interval, 0.85-0.91).

Conclusions: Low statin adherence may contribute to an elevated CVD risk in older adults exposed to high PM2.5 concentrations, while moderate-to-high statin adherence may reduce the risk of CVD regardless of PM2.5 levels.