# Assessing the Impact of External and Internal Factors on Emergency Department Overcrowding

## TL;DR

This study finds that weather, football games, and hospital operations affect emergency department wait times, helping hospitals prepare for busy periods.

## Contribution

The study identifies novel temporal relationships between external events and ED overcrowding, including delayed effects of football games and weather.

## Key findings

- Bad weather, especially thunderstorms, and clear weather both increase ED wait times.
- Football games 12 hours before game time correlate with increased ED crowding.
- Boarding count and hospital census show time-dependent effects on ED overcrowding.

## Abstract

Emergency departments often have long wait times, but we do not fully understand all the factors that contribute to ED overcrowding. This study looked at how weather, football games, holidays, and hospital operations affect ED waiting times at a major medical center over four years. We found that bad weather, especially thunderstorms, leads to more people waiting in the ED. Surprisingly, clear weather also increased wait times. Football games caused more crowding 12 h before game time, likely because of pre-game injuries and celebrations. Weekends and federal holidays had fewer people waiting, probably because people delay non-urgent visits when regular doctors are not available. The number of patients stuck in the ED waiting for hospital beds (boarding) and overall hospital fullness showed complex patterns. When measured at different time points, their effects changed from increasing to decreasing wait times, showing that timing matters in understanding ED crowding. These findings can help hospitals better predict busy periods and adjust staffing. For example, hospitals could add extra staff before thunderstorms or football games. Understanding these patterns helps hospitals prepare for crowding before it happens, potentially reducing your wait time when you need emergency care.

Objectives: This study analyzes factors influencing Emergency Department (ED) overcrowding by examining the impacts of operational, environmental, and external variables, including weather conditions and football games. Materials and Methods: This retrospective observational study analyzed emergency department (ED) tracking and hospital census data from a southeastern U.S. academic medical center covering 2019–2023. These data were merged with corresponding weather, football event, and federal holiday data. The dependent variable was the hourly waiting count in the ED, our operational measure of overcrowding. Seven regression models were developed to assess different predictors across various timestamps. Results: Weather conditions were significantly correlated with increased ED waiting count in the Baseline Model, while federal holidays and weekends were consistently correlated with reduced waiting counts. Boarding count was positively correlated with ED waiting count when concurrent, but boarding counts 3 h and 6 h before showed significant negative correlations. Hospital census showed a negative correlation in the Baseline Model but shifted to a positive effect in other models, reflecting its time-dependent influence on ED operations. Football games 12 h before significantly correlated with increased waiting counts, while games 12 and 24 h after had no significant effects. Discussion: While existing research typically focuses on limited variables and narrow timeframes, the temporal relationships between operational and non-operational factors affecting ED overcrowding remain understudied, particularly the delayed impacts of external events and environmental conditions. Conclusions: This study emphasizes the importance of incorporating both operational and non-operational factors to understand ED patient flow. Identifying robust predictors such as weather conditions, federal holidays, boarding count, and hospital census can inform dynamic resource allocation strategies to mitigate ED overcrowding effectively.