Young adulthood cognitive ability predicts statin adherence in middle-aged men after first myocardial infarction : a Swedish National Registry study

Background: Cognitive ability (CA) is positively related to later health, health literacy, health behaviours and longevity. Accordingly, a lower CA is expected to be associated with poorer adherence to medication. We investigated the long-term role of CA in adherence to prescribed statins in male patients after a first myocardial infarction (MI). Methods: CA was estimated at 18-20 years of age from Military Conscript Register data for first MI male patients (<= 60 years) and was related to the one- and two-year post-MI statin adherence on average 30 years later. Background and clinical data were retrieved through register linkage with the unselected national quality register SWEDEHEART for acute coronary events (Register of Information and Knowledge about Swedish Heart Intensive Care Admissions) and secondary prevention (Secondary Prevention after Heart Intensive Care Admission). Previous and present statin prescription data were obtained from the Prescribed Drug Register and adherence was calculated as >= 80% of prescribed dispensations assuming standard dosage. Logistic regression was used to estimate crude and adjusted associations. The primary analyses used 2613 complete cases and imputing incomplete cases rendered a sample of 4061 cases for use in secondary (replicated) analyses. Results: One standard deviation increase in CA was positively associated with both one-year (OR 1.15 (CI 1.01-1.31), P< 0.05) and two-year (OR 1.14 (CI 1.02-1.27), P< 0.05) adherence to prescribed statins. Only smoking attenuated the CA-adherence association after adjustment for a range of > 20 covariates. Imputed and complete case analyses yielded very similar results. Conclusions: CA estimated on average 30 years earlier in young adulthood is a risk indicator for statin adherence in first MI male patients aged <= 60 years. Future research should include older and female patients and more socioeconomic variables