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 185 252 postdischarge statin initiators. There were 50 015 subsequent ASCVD rehospitalisations including 2858 in-hospital death during 7 years 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.
- secondary prevention
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Contributors JZL and SF have made substantial contributions to the conception and design of the study, interpretation of data and drafting of the article. WYS, STH, CLL, STC and MSL have made substantial contributions to the conception and design of the study, acquisition of data, analysis and interpretation of data and drafting the article. VCT has made substantial contributions to the interpretation of data and drafting of the article. All authors were involved in revising the study critically for important intellectual content and gave final approval of the version to be submitted.
Funding This study was sponsored by Pfizer which is the manufacturer of Lipitor, the original brand of atorvastatin (Study ID A2581195). Editorial assistance was provided by APCER Life Sciences and funded by Pfizer.
Disclaimer Pfizer management was not involved in the review and interpretation of the results; the interpretation of the results was only from the authors. All analyses were done by the Formosan Medical Association; in fact, Pfizer did not have access to the data thus would not be able to, and did not, analyse the data. Because of this, the analyses were not repeated by another independent group. Pfizer follows the ICMJE standards, and this was clearly specified in the contract with the academic contractor Formosan Medical Association for this study: 'For all Publications, Investigator will comply with recognized ethical standards concerning publications and authorship, including Section II–'Ethical Considerations in the Conduct and Reporting of Research' of the Uniform Requirements for Manuscripts Submitted to Biomedical Journals, http://www.icmje.org/index.html%23authorship, established by the International Committee of Medical Journal Editors.'
Competing interests Among the authors of this study, WYS, JZL and SF are employees of Pfizer. STH, STC and MSL received research grant from Pfizer. VCT, who is an employee of APCER, received funding from Pfizer. CLL received consultancy fee from Pfizer.
Ethics approval The study protocol was reviewed by the Research Ethics Committee of the National Taiwan University, and was granted waiving of ethics approval and individual consent in accordance with local regulations.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Data are available upon reasonable request.
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