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Seasonality Patterns in Croup Presentations to Emergency Departments in Alberta, Canada: A Time Series Analysis

Rosychuk, Rhonda J. PhD*†; Klassen, Terry P. MD, MSc*‡§; Voaklander, Donald C. PhD; Senthilselvan, Ambikaipakan PhD; Rowe, Brian H. MD, MSc∥¶

doi: 10.1097/PEC.0b013e31821314b0
Original Articles

Introduction: Croup is a common pediatric respiratory illness presenting to the emergency department (ED) in the fall and winter months. Most cases are caused by parainfluenza viruses. We examine the monthly patterns of young children who made croup-related visits to EDs in Alberta, Canada.

Methods: Emergency department visits were identified in provincial administrative databases to obtain all ED encounters for croup made by young children (aged ≤2 years) during 6 years (April 1, 1999, to March 30, 2005). Time series models (seasonal autoregressive integrated moving average) were developed to capture temporal and seasonal trends and predict future presentations.

Results: Overall, 27,355 croup-related ED visits were made during the study period. More males (62%) than females presented, and most (43%) were younger than 1 year. Differences were observed in the number of visits made in odd and even years. Peak visits occurred in November for odd years and in February for other years. Strong seasonal patterns at 12 months were detected and included in the modeling.

Conclusions: We observed the presence of a clear biennial pattern of croup ED visits. The seasonal autoregressive moving average models and predictions offer insights into the epidemiology of croup-related visits to EDs and may be helpful in planning both research and resource needs.

From the *Department of Pediatrics, University of Alberta; †Women and Children's Health Research Institute, Edmonton, Alberta; ‡Department of Pediatrics and Child Health, University of Manitoba, Winnipeg, Manitoba; §Manitoba Institute of Child Health, Winnipeg, Manitoba, Canada; Departments of ∥Public Health Sciences, School of Public Health, Edmonton, and ¶Emergency Medicine, University of Alberta, Edmonton, Alberta, Canada.

Reprints: Rhonda J. Rosychuk, PhD, Department of Pediatrics, University of Alberta, 9423 Aberhart Centre, 11402 University Ave NW, Edmonton, Alberta, Canada T6G 2J3 (e-mail:

This work was made possible by an operating grant from the Canadian Institutes of Health Research. Dr Rosychuk is supported by the Alberta Heritage Foundation for Medical Research as a health scholar. Dr Rowe is supported by the Government of Canada as a 21st-Century Canada Research Chair.

None of the authors declares any potential conflicts of interest.

This study is based, in part, on data provided by Alberta Health andWellness. The interpretation and conclusions contained herein are those of the researchers and do not necessarily represent the views of the Government of Alberta. Neither the Government nor Alberta Health and Wellness expresses any opinion in relation to this study.

© 2011 Lippincott Williams & Wilkins, Inc.