Estimating the number of traffic crash-related cervical spine injuries in the United States; An analysis and comparison of national crash and hospital data

Background: Cervical spine injury is a common result of traffic crashes, and such injuries range in severity from minor (Le. sprain/strain) to moderate (intervertebral disk derangement) to serious and greater (fractures, dislocations, and spinal cord injuries). There are currently no reliable estimates of the number of crash-related spine injuries occurring in the US annually, although several publications have used national crash injury samples as a basis for estimating the frequency of both cervical and lumbar spinal disk injuries occurring in lower speed rear impact crashes. Purpose: To develop a reliable estimate of the number of various types of cervical spine injuries occurring in the US by comparing data from national crash injury to national hospital ED and inpatient samples. Study Design: Comparative cross-sectional Methods: Cervical spine injury data were accessed, analyzed, and compared from 3 national databases; the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS), Nationwide Emergency Department Sample (NEDS), and the Nationwide Inpatient Sample (NIS). Results: It is estimated that there are approximately 869,000 traffic crash-related cervical spine injuries seen in hospitals in the US annually, including around 841,000 sprain/strain (whiplash) injuries, 2800 spinal disk injuries, 23,500 fractures, 2800 spinal cord injuries, and 1500 dislocations. Because of a highly restrictive inclusion criteria for both crash and injury types, as well as a very small sample size, the NASS-CDS underestimated all types of crash-related cervical spine injuries seen in US hospital emergency departments by 84 %. The injury type with the largest degree of underestimation in the NASS-CDS was cervical disk injuries, which were estimated at an 88% lower frequency than in the NEDS. National insurance claim data, which include cases of cervical disk injury diagnosed both in and outside of the ED, indicate that the NEDS likely undercounts cervical disk injuries by 92 %, and thus the NASS-CDS correspondingly undercounts such injuries by 99 % or more. Conclusions: Because of a limited sample size and restrictive criteria for both crash and injury inclusion, the NASS-CDS cannot be used to estimate the number of crash-related spinal injuries of any type or severity in the US. The most inappropriate use of the database is for estimating the number of spinal injuries resulting from low speed rear impact collisions, as the NASS-CDS samples fewer than 1 in 100,000 of the cervical spine injuries of any type occurring in low speed rear impact collisions.