Impact of Pre-Existing Depression on In-Hospital and 1-Year Outcomes of Acute Myocardial Infarction: A Population-Based Study

Abstract

Introduction: Depression has been identified as a risk factor for Acute Myocardial Infarction (AMI); however, uncertainty persists regarding the prognostic implications of pre-existing depression and its treatment in patients with AMI. Objectives: This study aimed to investigate the prognostic role of depression in patients with AMI, evaluating in-hospital mortality, one-year mortality and one-year rehospitalization for recurrent AMI or acute heart failure. Methods: A population-based cohort study was conducted using administrative healthcare databases from Lombardy, Italy. The study included all adult patients (≥18 years) hospitalized between 2009 and 2022 with a diagnosis of acute myocardial infarction. Pre-existing depression was identified from patients’ clinical history recorded in the two years preceding the index myocardial infarction. Associations were estimated using multivariable models, including log-binomial regression for in-hospital mortality, Cox proportional hazards models for one-year mortality, and Fine and Gray competing risks models for one-year rehospitalization. All models were adjusted for baseline comorbidities and medication use. Results: The study included 213,057 adult patients with acute myocardial infarction, 29,254 (13.73%) of whom had pre-existing depression. Compared with patients without depression, those with depression were older, more likely to be female, and had a higher prevalence of baseline comorbidities and medication use. Pre-existing depression was independently associated with increased risk of in-hospital mortality (adjusted RR: 1.23; 95% CI: 1.19–1.27) and one-year mortality (adjusted HR: 1.26; 95% CI: 1.23–1.30). After adjustment for baseline characteristics, pre-existing depression was not associated with an increased risk of one-year rehospitalization (adjusted HR: 0.94; 95% CI: 0.91–0.97). Within the subgroup of patients with depression, no significant differences in the study outcomes were observed between treated and untreated individuals. Conclusions: These findings highlight the prognostic relevance of pre-existing depression in patients with acute myocardial infarction. An independent association with adverse outcomes was observed, with no significant differences between treated and untreated patients.