Study objective: Young infants with bronchiolitis are at risk for apnea. We seek to determine the rate of apnea in young infants with bronchiolitis and evaluate the performance of a predefined set of risk criteria for identifying infants at high risk for the development of apnea.
Methods: We identified a retrospective cohort study of patients treated in the emergency department (ED) of an urban pediatric tertiary care hospital from November 1995 to June 2000. All infants younger than 6 months who met our study definition of bronchiolitis and were admitted to the hospital were included. We developed, a priori, a set of risk criteria for identifying patients at high risk for apnea. Children were considered to be at high risk for apnea if (1) they were born at full term and were younger than 1 month, (2) they were born preterm (<37 weeks estimated gestational age) and were younger than 48 weeks postconception, or (3) the child's parents or a clinician had already witnessed an apnea episode with this illness before inpatient admission. Data pertaining to these risk criteria were collected from the ED physician's note. The primary outcome variable, the development of inhospital apnea, was assessed by review of the inpatient discharge summaries and medical records.
Results: Nineteen of 691 (2.7%; 95% confidence interval [CI] 1.7% to 4.3%) infants admitted with bronchiolitis developed apnea while hospitalized. All 19 patients with apnea were identified by our risk criteria (100% sensitivity; 1-sided 97.5% CI 82% to 100%). No patient classified as low risk subsequently developed apnea (100% negative predictive value; 1-sided 97.5% CI 99% to 100%).
Conclusion: The rate of apnea among young infants hospitalized with bronchiolitis is low. Our clinical risk criteria successfully identified a low-risk group of infants whose risk of apnea is less than 1%.