Statin adherence and persistence on secondary prevention of cardiovascular disease in Taiwan

Background Evidence and treatment guidelines support the use of statins in patients with established atherosclerotic cardiovascular disease (ASCVD) for secondary prevention of subsequent cardiovascular (CV) event. However, treatment adherence and persistence are still a concern. Methods We constructed a retrospective population-based cohort of patients, who initiated statin treatment within 90 days after discharge from hospital for ASCVD using the claims database of Taiwan National Health Insurance. Proportion of days covered (PDC) was used to measure statin adherence, and PDC >= 80% was defined as good adherence. The study outcomes were subsequent rehospitalisation or in-hospital death due to composite ASCVD, myocardial infarction or ischaemic stroke. Their associations with statin prescription adherence or persistence were analysed using time-dependent Cox proportional hazards model. Results The study cohort included 185252 postdischarge statin initiators. There were 50015 subsequent ASCVD rehospitalisations including 2858 in-hospital death during 7years of study period. Good adherence was significantly associated with lower risk of ASCVD rehospitalisation (adjusted HR (aHR) 0.90; 95% CI 0.87 to 0.92) and significantly lower risk of in-hospital death (aHR 0.59; 95%CI 0.53 to 0.65). Compared with constant use of statin, patients in the three less persistent states (recent stop, non-persistence and intermittent use) were associated with higher risk of subsequent ASCVD rehospitalisation, aHRs were 1.16, 1.13 and 1.26, respectively (all p<0.05). The increased risks were consistent with specific outcome of acute myocardial infarction and ischaemic stroke. Also, patients in the recent stop period had significantly higher risk for fatal CV event. Conclusions Good adherence and persistence to statin therapy are significantly associated with lower risk of secondary ASCVD rehospitalisation and in-hospital death.