The relationship between vehicle roof crush and head, neck and spine injury in rollover crashes.

BACKGROUND It is well established that rollover crashes are associated with a higher risk of serious injury and death than other types of crashes. Some of the most serious injuries that can result from a rollover crash are those to the head, neck and spine. The mechanism of injury to these body parts in a rollover is a matter of dispute in the literature. Some authors have concluded that the magnitude of vehicle roof deformation or vertical roof crush resulting from a rollover crash is not causally associated with head and neck injury severity, while others offer support for a causal association between roof crush and the degree of injury. A better understanding of the cause of serious injuries resulting from rollover crashes is important for improving injury prevention. METHODS This study utilized data from the National Automotive Sampling System--Crashworthiness Data System (NASS-CDS) for the years 1997 through 2007. Both cross-sectional and matched case-control designs along with a new composite injury metric termed the Head, Neck and Spine New Injury Severity Score (HNS-NISS) were used to analyze these data. RESULTS The cross-sectional analysis demonstrated a 64% (95% CI: 26-114%) increase in the odds of a life-threatening injury as estimated by the HNS-NISS with every 10 cm of increased roof crush. The results of the matched case-control analysis demonstrated a 44% (95% CI: 8-91%) increase in the odds of sustaining any injury to the head, neck or spine with every 10 cm increase in roof crush. CONCLUSION These results lend statistical support to a causal association between roof crush and head, neck and spine injury severity. Though they do not constitute definitive proof, they do contradict previously published theories suggesting that roof deformation is unrelated to such injuries.