In-hospital myocardial infarction and adherence to evidence-based drug therapies: a real-world evaluation

OBJECTIVES: This study aimed to measure adherence to chronic polytherapy following an acute myocardial infarction (AMI) and to find out associations between adherence and the setting of AMI onset (in vs out of hospital) as well as other determinants. DESIGN: Retrospective follow-up study. SETTING: Population living in the Lazio Region, Italy. PARTICIPANTS: This study included 25 779 hospitalised patients with a first diagnosis of AMI in 2012–2016, after the exclusion of those with hospital admission for AMI or related causes in the previous 5 years. PRIMARY AND SECONDARY OUTCOME MEASURES: Patients were classified as in-hospital AMI (IH-AMI) or out of hospital AMI (OH-AMI) according to present-on-admission codes. Adherence was measured based on prescription claims during a 6-month follow-up after hospital discharge, using medication possession ratio (MPR). Adherence to chronic polytherapy was defined as MPR ≥75% to at least 3 of the following medications: antithrombotics, betablockers, ACE inhibitors/angiotensin receptor blockers and statins. RESULTS: Among the entire cohort, 1 044 (4%) patients suffered IH-AMI. Overall, 15 440 (60%) patients were deemed adherent to chronic polytherapy. Female gender, older age, mental disorders, renal disease, asthma and ongoing concomitant treatments were factors associated with poor adherence. By contrast, patients with more severe AMI and those already taking evidence-based (E-B) drugs were more likely to be adherent. A strong association between the setting of AMI onset and adherence was observed: IH-AMI patients were 46% less likely to be adherent to E-B medications during their 6-month follow-up as compared with OH-AMI patients (OR 0.54; 95% CI 0.47 to 0.62; p<0.001). CONCLUSION: Pharmacotherapy is not consistent with clinical guidelines, especially for IH-AMI patients. Our findings provide evidence on a previously unidentified groups of patients at risk for poor adherence, who might benefit from greater medical attention and dedicated healthcare interventions.