Effect of Seasonality on Variation Among Patients Presenting With Rib Fractures in the United States.

Background: A prior single-site study from the Midwest exploring seasonality of traumatic rib fractures found injuries are more common during summer months and lower in winter months. There have been no modern studies evaluating seasonality of these common injuries nationally. Our aim was to describe temporal and spatial distribution of rib fractures in the United States. We hypothesized presentations for traumatic rib fractures follow a seasonal pattern, with greater frequency of rib fractures in the summer and lower levels in the winter.

Methods: We obtained hospital emergency department (ED) encounter data from Nationwide Emergency Department Sample (NEDS) from January 1, 2018 to December 31, 2018. We used ICD-10 codes to identify all patients with diagnostic codes specific to rib fractures. To examine seasonal patterns, we constructed negative binomial regression models using seasons as covariates to predict incidence of rib fracture encounters across regions.

Results: Of 15,439,004 trauma-related ED encounters in 2018, 384 431 (2%) encounters included a diagnosis of rib fracture(s). The percentage of ED trauma encounters with rib fractures was similar across the 4 regions. Rib fractures were more common in the summer in the Midwest, South, and West as compared to winter [22% (95% CI = 10-34%, = .007), 12% (95% CI = 5-20%, = 0.02), and 11% (95% CI = 5-17%, = .008), respectively].

Discussion: Our hypothesis was generally supported by our evaluation of NEDS. However, while seasonal variation in rib fractures does appear to exist in the Midwest, South, and West, this variation is not ubiquitous across the United States.