Background: Brief Resolved Unexplained Events (BRUE) are sudden, brief, and resolved events that take place in infants. They manifest as breathing irregularities, changes in colour, muscle tone, or responsiveness. While guidelines advise minimal testing and hospitalization for low‑risk infants, management of high‑risk cases remains uncertain due to insufficient evidence‑based protocols.This study aimed to evaluate whether hospitalization provided additional benefit in identifying an explanatory diagnosis, initiating targeted treatment, or observing recurrence of the episode in patients under 1 year of age who attended the Emergency Service with an initial diagnosis of BRUE who presented with apnea.Methods: This is a multicenter cross-sectional observational study through retrospective analysis of electronic clinical records, involving three hospitals with a shared Integrated Emergency Service. A screening was conducted that included 569 infants who attended the Emergency Service between January 2017 and June 2024, triaged as BRUE.Results: 71 infants were hospitalized after an episode meeting the criteria of BRUE with apnea documented. The median age at presentation was 36 days (IQR: 14–66), 53.5% were male, and the median gestational age was 39 weeks (IQR: 37–39) with 21.1% being preterm. Overall, 97.2% of these cases were classified as high-risk BRUEs.Median hospitalization was 3 days (IQR: 2–5). 52.1% of the patients received at least one complementary diagnostic test during hospitalization. The most common among them were a complete blood count (48.6%), C-reactive protein dosing (48.6%) and echocardiography (45.9%).Diagnosis was established in 66.2% of the infants, most frequently gastroesophageal reflux (42.6%), episode of choking (17.0%), upper respiratory infection (12.8%), and acute bronchiolitis (10.6%). Specific therapy was started in 23.9%, and recurrence during hospitalization happened in 7.0% of hospitalized infants. No deaths were observed.After a median follow-up of 3.0 years (IQR: 0.7–5.7), 5.6% experienced recurrence of BRUE events. Of the 41 patients referred to the hospital's outpatient follow-up, 6 (14.6%) had another diagnosis that could account for the BRUE event, including gastroesophageal reflux, breath‑holding spells, congenital heart disease, and epilepsy.Conclusion: Hospitalization of infants younger than 1 year who had BRUE and apnea resulted in a high definitive diagnosis rate, predominantly gastroesophageal reflux, and enabled targeted therapy initiation in almost one-quarter of infants. These results are in favor of the contribution of hospitalization in diagnosing and managing of high-risk BRUE infants that present with apnea.
