ABSTRACT. Objective. It is uncertain whether pediatric and general emergency departments have different admitting practices regarding children with bronchiolitis. The objective of this study was to quantify the differences in admission practices between pediatric and general emergency departments of children with bronchiolitis in 1 North American metropolitan area, controlling for various factors such as clinical severity, comorbid conditions, and socioeconomic status.Design. Retrospective cohort review of emergency department visits from April 1992 to March 1997.Setting. Five emergency departments (1 pediatric and 4 general) serving the Calgary Health Region, which encompasses ϳ850 000 people.Patients. All children residing within the region who visited a regional emergency department and were diagnosed to have bronchiolitis (International Classification of Diseases, Ninth Revision code 466.1, primary or secondary diagnosis).Main Outcome Measure. Population-standardized estimates of admission rates.Results. The medical charts of 3091 children diagnosed to have bronchiolitis during the study period were reviewed. Of this number, 2496 children were evaluated at the pediatric emergency department, and 629 (25%) were admitted. The remaining 595 (19%) were evaluated at the general emergency departments, and 221 (37%) were admitted. Controlling for age, gender, estimated family income based on postal code, medical comorbidity, and clinical severity estimated by presenting respiratory rate and room air oxygen saturation, populationstandardized estimates for admission rates at the pediatric and general emergency departments were 24% (standard error: 1%) and 43% (standard error: 2%), respectively.Conclusion. Children diagnosed to have bronchiolitis at the Calgary Health Region's pediatric emergency department were about half as likely to be admitted to the hospital as children diagnosed at the region's general emergency departments. Pediatrics 2002;110(4). URL: http://www.pediatrics.org/cgi/content/full/110/4/e49; bronchiolitis, hospitalization rates, practice variation, emergency department. ABBREVIATIONS. CHR, Calgary Health Region; International Classification of Diseases, Ninth Revision; CI, confidence interval. B ronchiolitis is an extremely common childhood disease that accounts for a significant proportion of pediatric hospitalizations. 1 Investigators, using the technique of small-area analysis, have found marked variations in hospitalization rates of children with bronchiolitis with reports of up to sixfold differences in rates per 100 000 children. [2][3][4] This degree of variation is not unique to bronchiolitis, in that substantial variations in rates have been documented for a number of surgical procedures and diseases. 5,6 Although controversy exists as to which factors, in general, are most responsible for the variability in medical practices, in most cases differences in health care access and socioeconomic factors account for at least some proportion of the variability. 5,6 Likewise, in the case of b...