Elsevier

Annals of Emergency Medicine

Volume 42, Issue 3, September 2003, Pages 395-402
Annals of Emergency Medicine

Trauma
The Canadian C-Spine rule performs better than unstructured physician judgment

https://doi.org/10.1016/S0196-0644(03)00422-0Get rights and content

Abstract

Study objective

We compare the predictive accuracy of emergency physicians' unstructured clinical judgment to the Canadian C-Spine rule.

Methods

This prospective multicenter cohort study was conducted at 10 Canadian urban academic emergency departments. Included in the study were alert, stable, adult patients with a Glasgow Coma Scale score of 15 and trauma to the head or neck. This was a substudy of the Canadian C-Spine and CT Head Study. Eligible patients were prospectively evaluated before radiography. Physicians estimated the probability of unstable cervical spine injury from 0% to 100% according to clinical judgment alone and filled out a data form. Interobserver assessments were done when feasible. Patients underwent cervical spine radiography or follow-up to determine clinically important cervical spine injuries. Analyses included comparison of areas under the receiver operating characteristic (ROC) curve with 95% confidence intervals (CIs) and the κ coefficient.

Results

During 18 months, 6,265 patients were enrolled. The mean age was 36.6 years (range 16 to 97 years), and 50.1% were men. Sixty-four (1%) patients had a clinically important injury. The physicians' κ for a 0% predicted probability of injury was 0.46 (95% CI 0.28 to 0.65). The respective areas under the ROC curve for predicting cervical spine injury were 0.85 (95% CI 0.80 to 0.89) for physician judgment and 0.91 (95% CI 0.89 to 0.92) for the Canadian C-Spine rule (P<.05). With a threshold of 0% predicted probability of injury, the respective indices of accuracy for physicians and the Canadian C-Spine rule were sensitivity 92.2% versus 100% (P<.001) and specificity 53.9% versus 44.0% (P<.001).

Conclusion

Interobserver agreement of unstructured clinical judgment for predicting clinically important cervical spine injury is only fair, and the sensitivity is unacceptably low. The Canadian C-Spine rule was better at detecting clinically important injuries with a sensitivity of 100%. Prospective validation has recently been completed and should permit widespread use of the Canadian C-Spine rule.

Introduction

More than 13 million patients with potential neck injuries are evaluated in US emergency departments (EDs) annually, of whom approximately 30,000 have cervical spine injuries and 10,000 have spinal cord injuries.1, 2, 3, 4, 5 The results from 1 Canadian study would suggest that 185,000 alert, stable adults with potential cervical spine injuries are treated in Canadian EDs annually, 0.9% of whom have cervical spine fractures or dislocations.6 Previous reports have suggested that clinical judgment is inadequate for predicting cervical spine injuries.7, 8, 9 The American College of Surgeons Advanced Trauma Life Support course therefore recommends that “… a c-spine film … be obtained on every patient sustaining an injury above the clavicle, and especially a head injury.”10 Previous reports have supported universal screening for cervical spine injuries, and approximately 97% of US trauma centers have at one time routinely ordered cervical spine radiography for all trauma patients.11, 12, 13 A recent Canadian study revealed institutional imaging rates ranging from 37% to 72% for alert, stable trauma patients at risk for cervical spine injuries.6

Universal cervical spine radiography has yielded a positive test rate of less than 3% in most trauma series.8, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25 We estimate that 110,000 cervical spine radiography assessments are done each year in Canada on alert, stable, adult trauma patients, of which 98% are normal.6 The cost of inexpensive, high-volume tests may contribute more to rising health care costs than more expensive “high technology” procedures.26, 27 We estimate that more than CDN$30 million is spent annually in Canada on outpatient cervical spine radiography.28 Comprehensive radiography to clear the cervical spine requires a large time commitment on the part of medical and hospital staff, distracting them from other responsibilities.29 A recent survey found that 98% of 300 Canadian emergency physicians would consider using a sensitive, reliable decision rule for the use of cervical spine radiography, suggesting insight into the fallibility of current clinical judgment.30 Such a rule would have the potential to significantly reduce health care costs, improve efficiency, and improve patient care.

The Canadian C-Spine and CT Head (CCC) Study is a prospective multiphase multicenter study.31, 32 Phase I of the CCC study involved derivation of a decision rule for cervical spine radiography by using 8,924 patients from 10 Canadian urban teaching and community EDs.33 Variables were assessed for their interobserver agreement and for their univariate association with clinically important cervical spine injury. The final Canadian C-Spine rule, derived by multivariate recursive partitioning of the strongest variables, was found to be 100% sensitive for detecting the 151 clinically important injuries (Figure 1). To justify the time and effort involved in validating and disseminating a clinical decision rule, it is important to know whether the rule improves on diagnostic accuracy of unstructured physician judgment alone. We sought to determine whether the Canadian C-Spine rule would have performed better than physician judgment during Phase I of the CCC Study.

Section snippets

Methods

The multicenter, multiphase CCC Study was undertaken with reference to previously described guidelines for developing clinical decision rules.34, 35 This prospective observational cohort study was undertaken as part of phase I of the CCC Study. It was carried out in 10 Canadian urban teaching and community EDs. Inclusion criteria were all ambulatory or immobilized adult patients who (1) were hemodynamically stable (systolic blood pressure ≥90 mm Hg and respiratory rate between 10 and 24

Results

This component of the CCC Study took place from October 1996 to April 1999. There were 6,265 patients enrolled by more than 200 physicians. Patient characteristics are summarized in Table 1. Assessments for 564 (9%) of the patients were carried out by resident physicians. Patients had been transferred from another institution in 180 (3%) cases. The mean patient age was 36.5 years (range 16 to 97 years), and 50.6% were men. Sixty-four patients (1.0%) had at least 1 clinically important cervical

Discussion

Overall, physician judgment based on unstructured assessment alone is relatively sensitive for predicting zero risk of cervical spine injury in adult blunt trauma patients. In this study, however, physicians' unstructured judgments did miss a small number of important injuries. The recently validated Canadian C-Spine rule performed better than unstructured physician judgment in predicting the absence of important cervical spine injury. The Canadian C-Spine rule has the potential to safely

Acknowledgements

We thank the following for their assistance: Erica Battram, BA, Kim Bradbury, RN, Teresa Cacciotti, RN, Pamela Sheehan, RN, Taryn MacKenzie, RN, Kathy Bowes, RN, Karen Code, RN, Virginia Blak-Genoway, RN, Debbie Karsh, RN, Sharon Mason, RN, Percy MacKerricher, RN, Jan Buchanan, BSN (study nurses); My-Linh Tran and Emily Moen (data management); Irene Harris (manuscript preparation); and all the physicians, nurses, and clerks at the study sites who voluntarily and patiently assisted with case

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    Dr. Stiell holds a Distinguished Investigator Award and Dr. Schull a New Investigator Award, both from the Canadian Institutes of Health Research.

    Supported by peer-reviewed grants from the Medical Research Council of Canada (MT-13699) and the Ontario Ministry of Health Emergency Health Services Committee (11896N).

    Reprints not available from the authors.

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