Based on studies with modest methodologic quality and 1 direct comparison, the Canadian C-spine rule appears to have better diagnostic accuracy than the National Emergency X-Radiography Utilization Study (NEXUS) criteria when used to assess the need for cervical spine imaging, say authors of a systematic review published in CMAJ. Future studies need to follow rigorous methodologic procedures to ensure that the findings are as free of bias as possible, they add.

For this review, the authors identified studies by an electronic search of CINAHL, Embase, and MEDLINE. They included articles that reported on a cohort of patients who experienced blunt trauma and for whom clinically important cervical spine injury detectable by diagnostic imaging was the differential diagnosis, evaluated the diagnostic accuracy of the Canadian C-spine rule or NEXUS or both, and used an adequate reference standard. They assessed the methodologic quality using the Quality Assessment of Diagnostic Accuracy Studies criteria. They used the extracted data to calculate sensitivity, specificity, likelihood ratios, and posttest probabilities.

Fifteen studies of modest methodologic quality were included in the review. For the Canadian C-spine rule, sensitivity ranged from 0.90 to 1.00 and specificity ranged from 0.01 to 0.77. For NEXUS, sensitivity ranged from 0.83 to 1.00 and specificity ranged from 0.02 to 0.46. One study directly compared the accuracy of these 2 rules using the same cohort and found that the Canadian C-spine rule had better accuracy. For both rules, a negative test was more informative for reducing the probability of a clinically important cervical spine injury.