Abstract
BACKGROUND: Bipolar disorder (BD) in older adults is linked to significant medical comorbidities and hospitalization burden, yet nationwide data remain scarce. This study aims to compare younger versus older BD hospitalization trends, patient characteristics, and the impact of comorbidities on hospitalization outcomes in Portugal (2008-2015). METHODS: A retrospective observational study was conducted using a Portuguese administrative database, selecting hospitalization episodes of patients aged ≥ 60 years with a primary BD diagnosis. Variables analyzed included demographics, psychiatric comorbidities, Charlson Comorbidity Index (CCI), length of stay (LoS), in-hospital mortality, hospital charges, and readmissions. RESULTS: From a total of 21,793 BD hospitalizations, there were 4801 (22.0%) BD-related hospitalizations in the older age group, and the annual hospitalization rate was 23.4 per 100,000 inhabitants. The median admission age was 66.0 years, and 67.7% were female. BD type I with a manic episode (32.9%) was the most frequent subtype, and 85.5% of admissions were emergent. The median LoS was 18.0 days, significantly longer than in younger adults (p < 0.001). Readmission occurred in 52.4% of cases, with in-hospital mortality at 0.7%. Comorbidities were present in 23.0% of hospitalizations, with diabetes (13.1%) and dementia (3.2%) being most prevalent. LIMITATIONS: The study relies on secondary administrative data, subject to coding inaccuracies, and its retrospective design limits causal inferences. CONCLUSIONS: BD hospitalizations in older adults carry a high medical burden, with comorbidities impacting outcomes. Early screening, multidisciplinary care, and targeted interventions are crucial to improving management and reducing hospitalizations. Further research is needed to explore long-term outcomes and outpatient care strategies.