There were 84 studies reporting on SCI as a result of motor vehicle crashes (MVC) (table 7). These studies presented statistics from 30 different countries; all continental regions were covered by at least one study. A variety of data sources were used including national and regional registries and national, regional or local hospital admission/discharge records or surveys. The studies used a variety of methods to collect and aggregate data. North America had the most studies (N=26), primarily from the United States (N=17 studies), followed by Europe (N=23 studies).
The proportion of SCI related to MVCs ranged from 6.9% in Nepal (Shresta et al. 2007) to 89% in Nigeria (Olasode et al. 2006). The most frequent proportion fell within the 40-49.9% range (N=22 studies) followed by the 30-39.9% range (N=19 studies). Differences in inclusion criteria may be one of the primary reasons for the wide variation of reported estimates as some studies included all causes of SCI while others excluded non-traumatic causes or other subgroups such as patients with neurodegenerative diseases, or individuals with or without neurological deficits.
In the United States and Canada, MVCs are the most common cause of SCI. Most recent estimates indicate MVCs account for 41% to 45% of SCIs in the United States (National Spinal Cord Injury Statistical Center February 2010; DeVivo and Chen 2011). In British Columbia, Alberta, and Manitoba Canada, MVCs are the primary cause of SCI (Lenehan et al 2012; Dryden et al. 2003; McCammon and Ethans 2011). Data from Manitoba indicated that the relative proportion of SCIs resulting from MVCs declined over time as indicated by decreasing frequencies among three different cohorts (47.4,%, 39.3%, 34.9%) sampled at three different time points between 1981 and 2007 (McCammon and Ethans 2011). Over this time, an increase in the frequency of females incurring a SCI due to MVCs was also observed (McCammon and Ethans 2011). Contrary to this, Pirouzmand (2010) reports an increase in relative frequencies of SCI due to MVCs from 1986 to 2006, in Toronto, Ontario, Canada, and Couris et al. (2010) report consistent frequencies from 2003 to 2006 in all of Ontario, Canada, with more women (28.5%) than men (23.0%) sustaining SCI.
Most recent estimates from Europe indicate MVCs to be the leading cause of SCIs in regions of Spain, Iceland and Turkey, and the second most common in regions of Norway. In Aragon, Spain, MVCs were the most common cause of SCI (57.0%) between 1972 and 2008, with higher incidence in males than females for all ages (Van Den Berg et al. 2011). Similarly, Cosar et al. (2010) report MVCs have accounted for 55.1% of SCIs among 127 individuals taking part in an in-patient rehabilitation program in Turkey between 1996 and 2008. In two counties in Norway, MVCs were found to be the second leading cause (34.2%) of SCI between 1952 and 2001. During this observation period MVCs resulting in a SCI increased overall and specifically among younger (<30 years) males (Hagen et al. 2012).
In Asia, MVCs are the primary cause of SCI in Taiwan (58.8%) (Wu et al. 2011), Iran (52.0%) (Chabok et al. 2009), Saudi Arabia (85%) (Alshahri et al. 2012), India (45%) (Chhabra and Arora 2012) and in one study from China (Hua et al. 2013). Other studies from the region found that MVCs were the second leading cause of SCI, including in Beijing (22.3%) and other areas of China (Tianjin (34.1%; 36.4%) (Ning et al. 2011; Li et al. 2011; Wu et al. 2012) as well as Pakistan (32.0%) (Qureshi et al. 2010). Similar to other studies, MVCs leading to SCI were most common among young, males, with MVCs occurring due to fatigue with highway driving without the use of seatbelts (Ning et al. 2011).
Two papers with a specific focus on SCIs resulting from MVCs were found in the most recent update. One paper reporting on MVCs in the United States used both the Crash Injury Research Engineering Network (CIREN), and the National Automotive Sampling System’s Crashworthiness Data System (NASS-CDS) databases (Stein et al. 2011). The CIREN database includes only newer fleet of vehicles and thus newer safety features, in addition to the reporting of significant injuries, whereas the NASS-CDS database represents a national probability sample of vehicles that are involved in any police-reported MVCs. The authors found that among the more serious MVCs as those included in the CIREN database, 11.5% of case occupants (n=3,524) had cervical spine injuries, whereas 0.35% of all occupants (N=48,660,000) in the NASS-CDS database sustained a cervical spine injury. Rollover and other severe crashes led to much higher risk of cervical spine injury. Older individuals (>65 years) were at an increase risk of cervical spine injury. Seat belt use was effective at preventing cervical spine injuries whereas airbag deployment may increase the risk of sustaining a cervical spine injury when in a serious MVC.
Lieutaud et al. (2010) reported on data from an epidemiological database of every MVC requiring medical attention in health facilities in the Rhone area of France since 1995. From 1997 to 2006, 144 (0.15%) individuals suffered a SCI out of the 97,341 patients included in the database. Cervical SCIs were the most frequent type of injury. More motorcyclists sustained a SCI compared to other types of major spinal trauma. Being younger, male, a motorcyclist, and not wearing a seatbelt were identified as risk factors for SCI.