Association between seatbelt sign and internal injuries in the contemporary airbag era: A retrospective cohort study.

Background: Literature predating routine availability of airbags reported an association between seatbelt signs and internal injuries. We measured this association among patients involved in motor vehicle crashes (MVCs) with airbag deployment.

Methods: We conducted a retrospective cohort study by chart review of all MVC patients presenting to our Emergency Department (ED) during 1 January 2008-30 September 2015. We included all adult MVC patients in the driver or front passenger seats with both shoulder and lap seatbelts and airbag deployment. Two trained chart abstractors recorded data regarding restraints and airbag deployment. We obtained all other data via electronic medical record abstraction including demographics, injuries, and survival. We compared the prevalence of cervicothoracic and intra-abdominopelvic injuries between patients with a documented seatbelt sign versus no seatbelt sign using a logistic regression model.

Results: Of 1379 MVC patients, 350 met inclusion criteria. Of these, 138 (39.4%) had a seatbelt sign. The prevalence of cervicothoracic injury was higher among subjects with a documented seatbelt sign (54.3% versus 42.9%, p=0.036) Seatbelt sign predicted cervicothoracic injury with a positive likelihood ratio of 1.3 (95% CI 1.0-1.7) and negative likelihood ratio of 0.8 (95% CI 0.7-1.0). The odds ratio of cervicothoracic injury among patients with a seatbelt sign versus no seatbelt sign was 1.58 (95% confidence interval 1.02-2.46) in the logistic regression model. There was no association between seatbelt sign and intra-abdominopelvic injury (p=0.418).

Conclusions: In the setting of airbag deployment, there is an association between seatbelt sign and cervicothoracic injury but not intra-abdominopelvic injury.