In-hospital outcomes of acute myocardial infarction hospitalizations with versus without registered bipolar disorder: A nationwide administrative-data study

OBJECTIVE This study aimed to compare characteristics, treatment, and in-hospital outcomes of acute myocardial infarction (AMI) hospitalizations with versus without a registered bipolar disorder (BD) diagnosis. METHODS This retrospective observational study analyzed 99,382 AMI hospitalization episodes in Portuguese public hospitals from 2008 to 2015. The primary outcome was all-cause in-hospital mortality. Associations were examined using multivariable logistic regression, with Firth penalization for sparse outcomes. RESULTS BD was registered in 109 episodes (0.1%). These episodes occurred at younger ages (mean difference - 7.88 years, 95% confidence interval [CI] -9.93 to -5.83) and more frequently included a tobacco-use code (adjusted odds ratio [aOR] 2.52, 95% CI 1.63-3.88). Mortality was 13.8% with registered BD and 8.9% without registered BD (unadjusted OR 1.62, 95% CI 0.94-2.80); after adjustment for age, sex, calendar year, comorbidity burden, and AMI presentation, registered BD was associated with higher mortality (aOR 3.09, 95% CI 1.74-5.48). Firth regression produced a similar estimate (aOR 3.17, 95% CI 1.74-5.42). Registered BD was associated with lower odds of any revascularization (aOR 0.65, 95% CI 0.43-0.97) and percutaneous coronary intervention (aOR 0.54, 95% CI 0.35-0.82), but higher odds of coronary artery bypass grafting (aOR 2.84, 95% CI 1.24-6.53). CONCLUSION AMI hospitalizations with registered BD were rare and occurred at younger ages. Adjusted analyses suggested higher in-hospital mortality and differences in revascularization, but under-recording, the small number of outcome events in the registered-BD group, and residual confounding require cautious interpretation.