Bipolar Disorder and Medical Comorbidities: a Portuguese Population-based Observational Retrospective study (2008-2015)

Abstract

Background: Bipolar disorder (BD) is associated with an increased risk of poor health outcomes. This study aimed to evaluate the prevalence of medical comorbidity presented on Charlson Comorbidity Index (CCI) and analyse its association with hospitalization outcomes among BD inpatients. Methods: A population-based observational retrospective study was conducted using a Portuguese administrative database containing all mainland public hospitalization episodes. From 2008-2015, episodes with a primary diagnosis of BD were analysed. Outcomes included: length of stay (LoS), in-hospital mortality and discharge destination. Results: Overall, 20807 hospitalizations were analysed. Mean age at admission was 47.9±14.3 years, and episodes mostly refer to women (66.6%). Mean LoS was 19.5±21.5 days. A total of 2145 (10.3%) episodes had ≥1 CCI comorbidities, being diabetes the most prevalent (5.9%), followed by chronic pulmonary disease (1.4%), dementia (0.96%), liver (0.9%) and cerebrovascular diseases (0.8%). LoS was significantly higher for episodes with secondary diagnoses of congestive heart failure (p<0.001), cerebrovascular disease (p=0.043), dementia (p<0.001), diabetes without chronic complication (p<0.001), renal disease (p<0.001) and malignancy (p=0.015). Episodes with myocardial infarction, peripheral vascular disease, malignancy and renal disease diagnoses had higher in-hospital mortality. Limitations: Data were registered for administrative reasons rather than research purposes, and the unit of analysis were episodes, not patients. Confounding variables, not available in this database, could have impacted the results. Conclusions: In this nationwide study, greater comorbidity profile was associated with increased LoS, morbidity and in-hospital mortality. The detection and timely management of medical comorbid conditions will improve prognosis and prevent the high BD medical burden.