Bipolar Disorder in pediatric patients: A nationwide retrospective study from 2000 to 2015

Pediatric Bipolar Disorder (BD) has been the focus of increased attention. To date, in Portugal, there is no evidence available for pediatricBD-related hospitalization rates. This study aimed to describe and characterize all pediatric hospitalizations with a primary diagnosis of BD registered in Portugal from 2000 to 2015. A retrospective observational study was conducted. Pediatric (< 18 years) inpatient episodes with a primary diagnosis of BD were selected from a national administrative database. The ICD-9-CM codes 296.x (excluding 296.2x, 296.3x and 296.9x) identified the diagnosis of interest. Additionally, age at discharge, sex, psychiatric comorbidities, length of stay (LoS), admission type and date, in-hospital mortality and hospital charges were analyzed. A total of 348 hospitalizations, representing 258 patients, were identified. The overall population-based rate of hospitalizations was 1.18/100 000 youths. A non-linear increase throughout the study period was found. Patients were mostly female (60.6%), with a median age of 16 years (Q1-Q3:14–17). Admissions were mostly emergent (81%), and the median LoS was 14 days (Q1-Q3:7–24). Moreover, about 26% of all episodes were readmissions. Mean estimated charges per episode were 3503.10€, totalizing 1.20M€. Limitations include the use of secondary data and the retrospective nature of the study. Annual rates of pediatric BD hospitalizations showed a non-linear increase. These findings may contribute to better understand the pediatric BD burden. Nevertheless, more research is warranted, to better characterize sociodemographic and clinical trends in pediatric BD to prevent the high number of acute hospitalizations and readmissions of these patients.