Orthomageddon: A retrospective cohort study of weather-dependent variations in emergency department volume in a Canadian city

Abstract

Introduction

Unique weather patterns can dramatically increase the number of emergency department (ED) visits due to falls on snow or ice compared to winter averages. They can create “Orthomageddon” incidences; days when the number of orthopedic injuries dramatically exceeds average. The study objective was to identify weather-dependent differences in demographics, length-of-stay (LOS) predictors, and volume for fall-injury presenting to the ED. The authors placed emphasis on Chinook or Foehn phenomenon (rapid freeze-thaw cycles) common east of the Rocky Mountains.

Method

Patients with extremity and hip fractures from fall on snow or ice were identified from the Calgary Zone Alberta Health Services ED database from November 1st 2013 to March 31st 2018 (n = 3894).

High-volume dates were the 90th percentile of all dates by volume (n = 76). This equated to all dates with >10 fall-injuries. The authors compared post-Chinook, night-freezing, high-volume, and regular winter conditions.

Meteorological data was collected from the Environment Canada weather station at the Calgary International Airport.

Results

The authors identified 588 post-Chinook, and 1149 night-freezing presenters. Weather was strongly predictive of ED fall-injury volume. Night-freezing events (above-freezing temperatures prior to 1800 hours the preceding day, followed by freezing temperatures prior to 0600 hours the following day) correlated with elevated fall-injury volume (OR, 6.84; 95% CI, 5.88, 7.97) as were recent Chinook events (OR, 2.19; 95% CI, 1.84, 2.62).

Conclusion

Weather, particularly nighttime conditions, are highly predictive of winter, fall-related ED volume. This may inform future population-level alerts for dates of elevated fall risk and ED staffing patterns.