Changes of hospital-level variation in use of optimal medical treatment for long-term follow-up from a multi-level methodological approach

Abstract Background Contemporary guidelines documented that optimal medical therapy (OMT) should be prescribed to improve clinical outcome in patients with acute myocardial infarction (AMI). However, the changes of hospital-level variations in prescription rates of OMT for long-term follow-up are unknown. Purpose We aimed to investigate (1) impact of hospital-level variation on the use of each medication and OMT and (2) changes of hospital-level variation in prescription rates of individual medical therapy and OMT during the follow-up. Methods We examined hospital medications of 13,516 AMI patients without documented contraindications to antiplatelet agents, β-blockers (BB), angiotensin-converting enzyme inhibitors (ACE) /angiotensin II receptor blockers (ARB), or statins from the Korean Acute Myocardial Infarction Registry (KAMIR) – National Institute of Health (NIH) database. OMT was defined as use of all 4 indicated medications. Hierarchical generalized linear mixed models estimated hospital-level variation in prescription rates of OMT and each medication after adjustment for patient-level factors. Variation was explored with a median rate ratio (MRR), which estimates the relative difference in risk ratios of 2 hypothetically identical patients at 2 different hospitals. Results The prescription rates of OMT and each effective cardiac medications are presented in Figure. There were substantial decreases in the prescription rates for OMT (from 66.7% to 51.6%) and dual antiplatelet agents (from 99.1% to 50.4%) for 2 years follow-up. After adjustment for patient-level covariates, hospital-level MRR for OMT was 1.47 at discharge, indicating an 47% likelihood that 2 random hospitals would differ in treating identical AMI patients. As the prescription rates of OMT and each effective cardiac medications decreased, adjusted hospital-level MRR for OMT (from 1.47 to 1.22), BB therapy (from 1.35 to 1.15), ACE/ARB therapy (from 1.68 to 1.16), and statin therapy (from 1.19 to 1.06) decreased for 2-year follow-up, whereas MRR for dual antiplatelet therapy increased at 1 year (MRR; 1.61) and 2 years (MRR; 1.63) follow-up (Figure). Among patient-level factors, age >70 years, Killip class>2, obesity, hypertension, previous coronary artery disease, renal dysfunction, reduced ejection fraction, percutaneous coronary intervention was independently associated with the use of OMT. Conclusion Hospital-level variations in the use of OMT and each effective cardiac medications were observed at discharge, but weakened overtime, except for use of dual antiplatelet therapy.