Effects of lipid-lowering treatment intensity and adherence on cardiovascular outcomes in patients with a recent myocardial infarction: a Swedish register-based study

Background: Oral lipid-lowering treatment (LLT) is the standard of care for patients with cardiovascular disease (CVD). However, insufficient treatment intensity and poor adherence can lead to suboptimal treatment benefit, rendering patients at increased risk of CVD. Aims: The objective of this study was to evaluate trends in LLT intensity and adherence in Sweden over time, and their association with major adverse cardiovascular events (MACE) after recent myocardial infarction (MI), and also to assess the impact of transition from secondary to primary care on intensity and adherence. Methods and results: This retrospective observational cohort study used data from Swedish nationwide patient registers and included patients on LLT after an MI in the years 2010–2016 (n = 50,298; mean age, 68 years; 69% men). LLT intensity was evaluated over time (overall, for 2010–2013 and for 2014–2016) as the proportion of patients prescribed low-, moderate-, and high-intensity LLT. Adherence was assessed as the proportion of days covered. A combined measure of intensity and adherence was also considered. Differences in treatment patterns and MACE were assessed. Initiation of high-intensity LLT increased over the two time periods studied (2010–2013, 32%; 2014–2016, 91%). Adherence varied by LLT intensity and was highest in patients receiving high-intensity LLT (>80%), especially during the first time period. Little change in treatment intensity or the combined measure of intensity and adherence was observed after transition to primary care. There was a significant association between the combined measure of intensity and adherence and MACE reduction (hazard ratio [95% confidence interval] per 10% increase in the combined measure: 0.84 [0.82–0.86]; P < 0.01). Conclusion: The proportion of post-MI patients with high LLT intensity and adherence has increased in recent years, with little change after transfer from specialist to primary care. The combination of LLT intensity and adherence is important for preventing future cardiovascular events.