The Canadian C-Spine Rule for Radiography in Alert and Stable Trauma
Patients


Author Information <http://jama.ama-assn.org/issues/v286n15/rfull/#aainfo>
Ian G. Stiell, MD, MSc, FRCPC; George A. Wells, PhD; Katherine L.
Vandemheen, BScN; Catherine M. Clement, RN; Howard Lesiuk, MD; Valerie J. De
Maio, MD, MSc; Andreas Laupacis, MD, MSc; Michael Schull, MD, MSc; R.
Douglas McKnight, MD; Richard Verbeek, MD; Robert Brison, MD, MPH; Daniel
Cass, MD; Jonathan Dreyer, MD; Mary A. Eisenhauer, MD; Gary H. Greenberg,
MD; Iain MacPhail, MD, MHSc; Laurie Morrison, MD, MSc; Mark Reardon, MD;
James Worthington, MBBS
Context  High levels of variation and inefficiency exist in current clinical
practice regarding use of cervical spine (C-spine) radiography in alert and
stable trauma patients.
Objective  To derive a clinical decision rule that is highly sensitive for
detecting acute C-spine injury and will allow emergency department (ED)
physicians to be more selective in use of radiography in alert and stable
trauma patients.
Design  Prospective cohort study conducted from October 1996 to April 1999,
in which physicians evaluated patients for 20 standardized clinical findings
prior to radiography. In some cases, a second physician performed
independent interobserver assessments.
Setting  Ten EDs in large Canadian community and university hospitals.
Patients  Convenience sample of 8924 adults (mean age, 37 years) who
presented to the ED with blunt trauma to the head/neck, stable vital signs,
and a Glasgow Coma Scale score of 15.
Main Outcome Measure  Clinically important C-spine injury, evaluated by
plain radiography, computed tomography, and a structured follow-up telephone
interview. The clinical decision rule was derived using the
kappacoefficient, logistic regression analysis, and chi2 recursive
partitioning techniques.
Results  Among the study sample, 151 (1.7%) had important C-spine injury.
The resultant model and final Canadian C-Spine Rule comprises 3 main
questions: (1) is there any high-risk factor present that mandates
radiography (ie, age 65 years, dangerous mechanism, or paresthesias in
extremities)? (2) is there any low-risk factor present that allows safe
assessment of range of motion (ie, simple rear-end motor vehicle collision,
sitting position in ED, ambulatory at any time since injury, delayed onset
of neck pain, or absence of midline C-spine tenderness)? and (3) is the
patient able to actively rotate neck 45° to the left and right? By
cross-validation, this rule had 100% sensitivity (95% confidence interval
[CI], 98%-100%) and 42.5% specificity (95% CI, 40%-44%) for identifying 151
clinically important C-spine injuries. The potential radiography ordering
rate would be 58.2%.
Conclusion  We have derived the Canadian C-Spine Rule, a highly sensitive
decision rule for use of C-spine radiography in alert and stable trauma
patients. If prospectively validated in other cohorts, this rule has the
potential to significantly reduce practice variation and inefficiency in ED
use of C-spine radiography.
JAMA. 2001;286:1841-1848
JOC10637
More than 1 million patients with blunt trauma and potential cervical spine
(C-spine) injury are treated each year in US emergency departments (EDs). 1
<http://jama.ama-assn.org/issues/v286n15/rfull/#r1> , 2
<http://jama.ama-assn.org/issues/v286n15/rfull/#r2>  Among those patients
presenting with intact neurological status (arriving either walking or by
ambulance), the incidence of acute fracture or spinal injury is less than
1%. 3-5 <http://jama.ama-assn.org/issues/v286n15/rfull/#r3>  Due to concerns
about potentially disabling spinal injuries, most clinicians make liberal
use of C-spine radiography. 6-9
<http://jama.ama-assn.org/issues/v286n15/rfull/#r6>  Nevertheless, such
practice is inefficientmore than 98% of C-spine radiographs are negative for
fracture. 10-16 <http://jama.ama-assn.org/issues/v286n15/rfull/#r10>
Furthermore, there is considerable practice variation among well-trained
emergency physicians, with radiography rates ranging as much as 6-fold. 17
<http://jama.ama-assn.org/issues/v286n15/rfull/#r17>  Cervical spine
radiography is an example of a "little ticket" item, a low-cost procedure
that significantly adds to health care costs due to its high volumes of use.
18 <http://jama.ama-assn.org/issues/v286n15/rfull/#r18> , 19
<http://jama.ama-assn.org/issues/v286n15/rfull/#r19>
There are no widely accepted guidelines that have been shown to be both safe
and efficient in guiding the use of C-spine radiography. Recently, clinical
decision rules have been developed to guide physicians in making diagnostic
or therapeutic decisionsfor example, the use of radiography for patients
with ankle or knee injuries. 20-23
<http://jama.ama-assn.org/issues/v286n15/rfull/#r20>  A clinical decision
rule may be defined as a decision-making tool that is derived from original
research and that incorporates 3 or more variables from the history,
physical examination, or simple tests. 24
<http://jama.ama-assn.org/issues/v286n15/rfull/#r24> , 25
<http://jama.ama-assn.org/issues/v286n15/rfull/#r25>  The National Emergency
X-Radiography Utilization Study (NEXUS) low-risk criteria for C-spine
radiography were recently evaluated in a large study of EDs that found the
criteria to be 99.6% sensitive for clinically important injuries. 26
<http://jama.ama-assn.org/issues/v286n15/rfull/#r26>  However, the
specificity was only 12.9%, leading to concerns that use of the NEXUS
criteria would actually increase the use of radiography in some US
jurisdictions and in most countries outside of the United States.
We believe that the current inefficiency and variability of clinical
practice can be remedied with the development of an accurate, reliable, and
clinically sensible decision rule. Hence, the objective of this study was to
derive a clinical decision rule that would be highly sensitive for detecting
acute C-spine injury among patients sustaining blunt trauma who are alert
and stable but at risk for neck injury. This will ultimately allow
physicians to be more selective in their use of radiography without
jeopardizing patient care.



METHODS



Study Setting and Population

This prospective cohort study was conducted in 10 large Canadian community
and university hospitals and included consecutive adult patients presenting
to the ED after sustaining acute blunt trauma to the head or neck. We did
not include the many patients presenting with trivial injuries, such as
simple lacerations to the face.The treating physician's decision of whether
to order radiography had no bearing on the enrollment of patients into the
study. Patients were eligible for enrollment if they were at some risk for
C-spine injury either because they had neck pain from any mechanism of
injury, or because they had no neck pain but had all of the following: some
visible injury above the clavicles, had not been ambulatory, and had
sustained a dangerous mechanism of injury. In addition, patients had to be
alert, which was defined as a Glasgow Coma Scale (GCS) score of 15 (scale
range, 3-15), and stable, defined as normal vital signs (systolic blood
pressure >90 mm Hg and respiratory rate between 10 and 24/min).
Patients were excluded if they: (1) were younger than 16 years; (2) had
minor injuries, such as simple lacerations, and did not fulfill the first 2
inclusion criteria above; (3) had a GCS score lower than 15; (4) had grossly
abnormal vital signs; (5) were injured more than 48 hours previously; (6)
had penetrating trauma; (7) presented with acute paralysis; (8) had known
vertebral disease (ankylosing spondylitis, rheumatoid arthritis, spinal
stenosis, or previous cervical surgery), as determined by the examining
physician; (9) had returned for reassessment of the same injury; or (10)
were pregnant. Eligible patients transferred from other hospitals with
suspected C-spine injury were enrolled at the study sites with the proviso
that physicians complete the data form prior to reviewing radiographic
films. Many of these patients proved not to have C-spine injury. The
research ethics committees of the study hospitals approved the protocol
without the need for informed consent. Patients followed up had an
opportunity to give verbal consent during the telephone interview conducted
by a study nurse.
Standardized Patient Assessment

All patient assessments were made by staff physicians certified in emergency
medicine or by supervised residents in emergency medicine training programs.
The physician assessors were trained with a 1-hour session to evaluate
patients for 20 standardized clinical findings from the history, general
examination, and assessment of neurological status. These potential
predictor variables were selected by a team of investigators at a planning
consensus conference based on a review of the existing literature and on
results of a pilot study. Findings were recorded on a data collection sheet
prior to radiography. A subset of patients, where feasible, were
independently assessed by a second emergency physician to judge
interobserver agreement. An additional 5 demographic variables were obtained
from hospital records by study nurses.
Outcome Measures and Assessment

The primary outcome measure was clinically important cervical spine injury,
defined as any fracture, dislocation, or ligamentous instability
demonstrated by diagnostic imaging. Clinically unimportant cervical spine
injuries generally do not require stabilizing treatment or specialized
follow-up and the definition for this has been standardized based on the
results of a formal survey of 129 neurosurgeons, spinal surgeons, and
emergency physicians at 8 tertiary care hospitals. 27
<http://jama.ama-assn.org/issues/v286n15/rfull/#r27>  All C-spine injuries
were considered clinically important unless the patient was neurologically
intact and had 1 of 4 injuries: (1) isolated avulsion fracture of an
osteophyte (2) isolated fracture of a transverse process not involving a
facet joint (3) isolated fracture of a spinous process not involving the
lamina or (4) simple compression fracture involving less than 25% of the
vertebral body height.
After the clinical examination, patients underwent plain radiography of the
C-spine according to the judgment of the treating physician, not according
to any preset guidelines. Radiographs were interpreted by qualified staff
radiologists who were blinded to the contents of the data collection sheet.
The reliability of the radiography interpretations was assessed by having
all abnormal radiographs and 1% (randomly selected) of normal radiographs
reviewed by a second radiologist who was blinded to the first
interpretation. Radiography consisted of a minimum of 3 views. Patients also
underwent flexion-extension views and computed tomography of the C-spine at
the discretion of the treating physician.
Because not all patients with blunt trauma routinely undergo C-spine
radiography at the Canadian study sites, we could not ethically mandate
universal radiography for all eligible patients. Consequently, all enrolled
patients who did not have radiography underwent the structured 14-day proxy
outcome measure administered by telephone by a registered nurse. Patient
telephone numbers were verified by the treating emergency physician.
According to this tool, patients were classified as having no clinically
important C-spine injury if they met all of the following 4 explicit
criteria for 14 days: (1) neck pain rated as none or mild, (2) restriction
of neck movement rated as none or mild, (3) use of a cervical collar not
required, and (4) neck injury has not prevented return to usual occupational
activities. The assessment of these criteria was made by registered nurses
who were unaware of the patient's status for the individual predictor
clinical variables. Patients who did not fulfill the criteria were recalled
for clinical assessment and radiography. Patients who could not be reached
were excluded from the final study analysis. These criteria have been
previously shown to identify all C-spine injuries in a substudy that applied
the telephone follow-up questionnaire to a sample of 389 study patients
(including 66 with clinically important C-spine injury) who had all
undergone radiography. 28
<http://jama.ama-assn.org/issues/v286n15/rfull/#r28>
Data Analysis

The interobserver agreement for each variable was measured by calculating
the kappacoefficient, the proportion of potential agreement beyond chance,
along with 95% confidence intervals (CIs). 29
<http://jama.ama-assn.org/issues/v286n15/rfull/#r29> , 30
<http://jama.ama-assn.org/issues/v286n15/rfull/#r30>  kappaValues were not
calculated for variables collected from medical records (eg, age or
mechanisms of injury). Univariate analyses were used to determine the
strength of association between each variable and the primary outcome to aid
selection of the best variables for the multivariable analyses. The
appropriate univariate techniques were chosen according to the type of data.
For nominal data, the chi2 test with continuity correction was used; for
ordinal variables, the Mann-Whitney U test; and for continuous variables,
the unpaired 2-tailed t test, using pooled or separate variance estimates as
appropriate.
Those variables found to be both reliable (kappa>0.6) and strongly
associated with the outcome measure (P<.05) were combined using either
recursive partitioning or logistic regression. The objective was to find the
best combinations of predictor variables, ie, those highly sensitive for
detecting the outcome measure while achieving the maximum possible
specificity. Building of the regression model proceeded with forward
stepwise selection until no variables met the criteria for entry (P<.05) or
removal (P>.10) for the significance levels of the likelihood-ratio test.
Recursive partitioning was performed as an alternative technique using
KnowledgeSEEKER, version 3.1 (Angoss Software International, Toronto,
Ontario). 31 <http://jama.ama-assn.org/issues/v286n15/rfull/#r31> , 32
<http://jama.ama-assn.org/issues/v286n15/rfull/#r32>  Our experience
suggested recursive partitioning may be more suitable than logistic
regression when the objective is to correctly classify one outcome group at
the expense of the other (ie, where high sensitivity is more important than
overall accuracy).
The derived decision rule was cross-validated by comparing the
classification of all patients to their actual status for the primary
outcomes allowing estimates, with 95% CIs, of the sensitivity and
specificity of the rule. In addition, we conducted a statistical validation
using a jackknife nonparametric estimate of bias for the sensitivity,
specificity, and overall accuracy of the rule. 33
<http://jama.ama-assn.org/issues/v286n15/rfull/#r33> , 34
<http://jama.ama-assn.org/issues/v286n15/rfull/#r34>  The a priori sample
size was estimated to be 8000 patients and 120 injury cases, based on the
desired precision of 100% sensitivity for clinically important C-spine
injury with 95% confidence limits of 97% to 100%.



RESULTS



Between October 1996 and April 1999, 12 782 eligible patients were examined
at the study sites. Of these, 8924 patients were enrolled and assessed for
the primary outcome measure, clinically important C-spine injury, and thus
made up the final study group ( Table 1
<http://jama.ama-assn.org/issues/v286n15/fig_tab/joc10637_t1.html> ). Not
included in this study group were 3281 eligible patients examined but not
enrolled by the treating physicians. All characteristics of these
nonenrolled patients were very similar to those of the patients enrolled
except for slightly higher rates of arrival by ambulance (61% vs 54%),
transfer from another hospital (10% vs 4%), and incidence of C-spine injury
(3.2% vs 2.0%). Finally, 577 eligible patients were also not included in the
final study group because they did not undergo C-spine radiography and could
not be reached for the proxy outcome measure. This latter group were much
less severely injured: only 32% arrived by ambulance, 0.2% were transfers
from other hospitals, and only 0.9% were admitted to hospital. Of the
patients in the final study group, 6185 (68.9%) underwent C-spine
radiography and the remaining 31.1% underwent the structured 14-day
telephone proxy outcome measure administered by a registered nurse. Of all
study patients, 151 (1.7%) were determined to have a clinically important
C-spine injury. The radiologists showed 100% agreement in diagnosing C-spine
injury. An additional 28 (0.3%) patients were judged to have a clinically
unimportant C-spine injury, primarily avulsion fractures. No patient
contacted for the proxy outcome measure was later determined to have a
C-spine injury.
Table 2 <http://jama.ama-assn.org/issues/v286n15/fig_tab/joc10637_t2.html>
and Table 3
<http://jama.ama-assn.org/issues/v286n15/fig_tab/joc10637_t3.html>  show the
association between the predictor variables and clinically important C-spine
injury as determined by univariate analyses. Overall, we evaluated 25
primary predictor variables (20 from the physician's form and 5 from the
chart) as well as another 8 created by combination or cutpoints. Table 2
<http://jama.ama-assn.org/issues/v286n15/fig_tab/joc10637_t2.html>  also
shows the interobserver agreement for the primary clinical variables from
those patients (n = 150) examined by 2 physicians.
Logistic regression analysis ( Table 4
<http://jama.ama-assn.org/issues/v286n15/fig_tab/joc10637_t4.html> )
provided a model with good overall accuracy for discriminating cases with
clinically important C-spine injury (area under the receiver operating
characteristic curve, 0.91; P = .94 for the Hosmer-Lemeshow goodness-of-fit
test). We also conducted recursive-partitioning analysis, which ultimately
resulted in a more clinically acceptable model. The predictor variables in
this latter statistical model were then combined into a simple algorithm,
the "Canadian C-Spine Rule" ( Figure 1
<http://jama.ama-assn.org/issues/v286n15/fig_tab/joc10637_f1.html> ). This
clinical decision rule asks 3 basic questions and establishes the safety of
evaluating active range of motion by identifying high-risk and low-risk
factors.
The potential classification performance of the Canadian C-Spine Rule for
identifying 151 cases with clinically important C-spine injury reveals a
sensitivity (95% CI) of 100% (98%-100%) and a specificity of 42.5% (40%-44%)
( Table 5
<http://jama.ama-assn.org/issues/v286n15/fig_tab/joc10637_t5.html> ). From
the jackknife statistical analysis, we calculated the bias-corrected
estimates for sensitivity to be 100% and those for specificity to be 42.63%;
the bias for overall accuracy was estimated to be 2.12%. We estimate a
potential C-spine radiography rate of 58.2% in this cohort, a relative
reduction of 15.5% from 68.9%. The rule also would have identified 27 out of
28 patients with clinically unimportant C-spine injury. One 63-year-old
patient not identified had a small C3 osteophyte avulsion fracture and was
discharged from the ED with a cervical collar.



COMMENT



This represents the largest derivation study yet conducted of patients
having potential C-spine injury, evaluating the accuracy and reliability of
25 clinical variables and enrolling 8 times more patients than any previous
derivation study. We developed a highly sensitive clinical decision rule
that, if prospectively validated, will allow physicians to rationally order
C-spine radiography for alert and stable trauma patients who are at risk for
neck injury. This will lead to more timely and efficient use of resources
without jeopardizing patient care. This new Canadian C-Spine Rule identifies
those trauma patients who require C-spine radiography based on 3 simple
clinical questions. First, patients judged to be at high risk due to age,
dangerous mechanism of injury, or paresthesias must undergo radiography.
Second, patients with any 1 of 5 low-risk characteristics may safely undergo
assessment of active range of motion. Third, patients who are able to
actively rotate their neck 45° to the left and to the right, regardless of
pain, do not require C-spine radiography. The Canadian C-Spine Rule was
derived according to strict methodological standards and provides a very
tight CI around the estimated sensitivity of 100% for detecting injury.
Future studies will further evaluate the rule for accuracy and reliability,
acceptability to clinicians, and actual impact on patient care.
We believe that current use of C-spine radiography for alert and stable
trauma patients is very inefficient and highly variable. 12
<http://jama.ama-assn.org/issues/v286n15/rfull/#r12> , 15
<http://jama.ama-assn.org/issues/v286n15/rfull/#r15> , 16
<http://jama.ama-assn.org/issues/v286n15/rfull/#r16>  Most patients in the
United States undergo radiography regardless of their clinical presentation.
While Canadian practice is more selective, we have shown that there is very
large variation among hospitals and physicians in their use of C-spine
radiography. 17 <http://jama.ama-assn.org/issues/v286n15/rfull/#r17>  This
2-fold variation among hospitals and 6-fold variation among certified
attending emergency physicians persisted even after using multivariable
analysis to control for differences in severity of trauma. There is
considerable controversy among emergency physicians, neurosurgeons, and
trauma surgeons regarding indications for C-spine radiography. Some firmly
maintain that all trauma patients should undergo radiography. 3
<http://jama.ama-assn.org/issues/v286n15/rfull/#r3> , 7
<http://jama.ama-assn.org/issues/v286n15/rfull/#r7> , 35-37
<http://jama.ama-assn.org/issues/v286n15/rfull/#r35>  For example, in its
Advanced Trauma Life Support Course, the American College of Surgeons
recommends that " . . . C-spine films should be attained on every patient
sustaining an injury above the clavicle and especially a head injury." 38
<http://jama.ama-assn.org/issues/v286n15/rfull/#r38>  Other trauma
clinicians agree that a selective approach is ideal but do not give clear
recommendations. 39-41 <http://jama.ama-assn.org/issues/v286n15/rfull/#r39>
Most authors suggest that radiography may not be required in alert patients
with no pain or tenderness of the neck. 42-46
<http://jama.ama-assn.org/issues/v286n15/rfull/#r42>  Such an approach is
still very conservative, but only a few authors are willing to suggest that
radiography may be withheld in alert patients with neck pain if there is no
midline bone tenderness of the neck. 47
<http://jama.ama-assn.org/issues/v286n15/rfull/#r47> , 48
<http://jama.ama-assn.org/issues/v286n15/rfull/#r48>  According to Neifeld
and colleagues, 13 <http://jama.ama-assn.org/issues/v286n15/rfull/#r13>
"the real difficulty exists in patients who are awake, alert, have normal
physical examination findings and have minimal or no symptoms." This latter
group represents the largest group of blunt trauma patients and the greatest
potential for improved efficiency of radiography. Our own surveys have shown
that most Canadian physicians and those in the United States disagree with
guidelines for universal C-spine radiography and support evidence-based
guidelines if they are shown to be accurate and reliable. 49
<http://jama.ama-assn.org/issues/v286n15/rfull/#r49>
A number of studies have been conducted in recent years by emergency
physicians, trauma surgeons, and radiologists to identify a group of trauma
patients who do not need C-spine radiography. Unfortunately, these studies
have great variability in design and none could be considered robust
according to methodological standards for the development of clinical
decision rules. An exception are the US-based NEXUS criteria, which have
recently received prominent attention after the publication of a huge
validation study incorporating more than 34 000 patients. 26
<http://jama.ama-assn.org/issues/v286n15/rfull/#r26> , 48
<http://jama.ama-assn.org/issues/v286n15/rfull/#r48> , 50
<http://jama.ama-assn.org/issues/v286n15/rfull/#r50>  These guidelines state
that no C-spine radiography is required if patients satisfy all 5 low-risk
criteria: absence of midline tenderness, normal level of alertness, no
evidence of intoxication, no abnormal neurological findings, and no painful
distracting injuries. We have concerns about the sensitivity, specificity,
and reliability of these criteria. The authors' own calculated specificity
of 12% is very low and may actually lead to an increase in the use of
C-spine radiography in most countries outside of the United States.
Clinicians in Canada have found 2 of the criteria ("presence of
intoxication" and "distracting painful injuries") to be poorly reproducible.
We recently attempted a retrospective validation of the NEXUS criteria based
upon our database of 8924 patients and found that the criteria failed to
predict 10 of 148 clinically important injuries, yielding a sensitivity of
only 93%. 51 <http://jama.ama-assn.org/issues/v286n15/rfull/#r51>  We
believe that the NEXUS criteria should be further evaluated, prospectively
and explicitly, for sensitivity, specificity, and interobserver agreement in
multiple sites before they can be accepted for widespread clinical use.
One strength of our study was the strict adherence to methodological
standards for the derivation of clinical decision rules. 24
<http://jama.ama-assn.org/issues/v286n15/rfull/#r24> , 25
<http://jama.ama-assn.org/issues/v286n15/rfull/#r25> , 52-54
<http://jama.ama-assn.org/issues/v286n15/rfull/#r52>  The primary outcome
measure, clinically important C-spine injury, was clearly defined and was
assessed in a blinded fashion. In addition, the clinical findings used as
predictors were standardized and collected without knowledge of the outcome
measure. The reproducibility of the predictor findings was assessed by
having a subset of patients examined by 2 physicians. The study subjects
were selected without bias and based on preset criteria rather than on the
subjective decision of individual physicians to order C-spine radiography.
These patients represented a wide spectrum of clinical characteristics and
geographic sites, hence increasing generalizability. The mathematical
techniques for deriving the rule were explicit and appropriate. We believe
that the format of the rule, a simple list of questions, makes it clinically
sensible for the intended audience of busy emergency physicians.
Furthermore, the rule appears to be highly sensitive for the clinically
important outcome, making its use safe for patient care. In addition, it is
relatively specific, making it an efficient tool. The true impact of the
Canadian C-Spine Rule, however, can only be determined in a prospective
study to evaluate the accuracy, interobserver agreement, clinician
acceptability, and potential radiograph ordering rates in a new patient
population.
Conversely, our study has potential limitations that warrant discussion.
Some may be concerned about our use of clinically important C-spine injury
as the primary outcome. Our definition has, however, been well accepted by
Canadian academic neurosurgeons, spine surgeons, and emergency physicians.
We believe that this represents a pragmatic and very safe approach to
patient care. The priority of diagnostic imaging for these trauma patients
should be to identify C-spine injuries that require treatment and follow-up.
Clinically unimportant C-spine injuries, according to the academic surgeons
in our survey, require neither stabilizing treatment nor specialized
follow-up and are unlikely to be associated with long-term problems.
Furthermore, the Canadian C-Spine Rule has also proven to be very sensitive
for the clinically unimportant injuries, missing only 1 small avulsion
fracture that required treatment with a cervical collar only.
Another potential limitation is that not all study patients underwent
C-spine radiography. The Canadian clinicians in our study often withhold
diagnostic imaging for trauma patients whom they consider to be at low risk
for injury. Consequently, we could not ethically insist upon universal
radiography for all patients. Patients were only classified as having no
clinically important injury if they satisfied all criteria on the structured
14-day telephone proxy outcome tool. Patients who could not fulfill all
criteria were recalled for radiography and patients who could not be reached
were excluded from the final analysis. The proxy outcome tool has been
validated and shown to be very accurate in identifying patients with
clinically important injuries. In addition, we acknowledge that not all
eligible patients were enrolled in the study. However, this is not unusual
for a clinical study and we are confident that there was no selection
biasthe characteristics of patients not enrolled were very similar to those
of the patients who were enrolled.
The Canadian C-Spine Rule encompasses many variables that have previously
not been prominently considered in guidelines for the use of C-spine
radiography. We found that patients 65 years or older and those experiencing
paresthesias were at considerable risk of C-spine injury, and that all such
patients should undergo radiography. In addition, our data clearly
demonstrate that particular mechanisms of injury are associated with
substantially increased risk of important injury and that patients with such
injuries should not be further examined prior to radiography. Furthermore,
our results demonstrate that 5 factors put the patient at very low risk of
injury and allow safe assessment of range of motion: simple rear-end motor
vehicle collision, found to be in the sitting position in the ED, ambulatory
status at any time after the injury, delayed onset of neck pain, and absence
of midline C-spine tenderness. The final common pathway of the Canadian
C-Spine Rule requires patients to successfully demonstrate an ability to
rotate the neck actively left and right a minimum of 45°, regardless of
pain. This assessment mirrors clinical practice in Canada but would appear
to be a relatively uncommon approach in US sites that have adopted the NEXUS
criteria.
There are 2 potential implications of a decision rule or guideline for the
use of C-spine radiography in alert and stable trauma patients. First,
patient management would become standardized and more efficient. The great
variation of current practice and the extremely low yield of radiography
suggest a need for accurate and reliable guidelines. A sensitive and
specific decision rule would reduce the unnecessary use of radiography and
would allow much more rapid triage and evaluation of patients brought to the
ED by ambulance stretcher. Such patients often languish for hours on an
uncomfortable backboard before their C-spine is judged free of injury.
Second, an accurate decision rule could lead to significant savings for our
health care systems. The current variation in practice and very low yield of
C-spine radiography among alert and stable trauma patients would suggest
significant potential for reducing the use of this radiography. Our survey
of emergency physicians in 5 North American and European countries clearly
indicates a willingness to adopt a decision rule for C-spine radiography. 55
<http://jama.ama-assn.org/issues/v286n15/rfull/#r55>  Based on our studies
that show large reductions in the use of ankle radiography after the
implementation of the Ottawa Ankle Rules, 20
<http://jama.ama-assn.org/issues/v286n15/rfull/#r20> , 21
<http://jama.ama-assn.org/issues/v286n15/rfull/#r21>  we estimate that a 25%
to 50% relative reduction in the use of C-spine radiography could be safely
achieved.
There is currently much controversy in the literature and much variation and
inefficiency in clinical practice regarding the use of C-spine radiography
for alert and stable trauma patients. Our study has developed the highly
sensitive Canadian C-Spine Rule to identify a large group of patients for
whom C-spine radiography is unnecessary. If prospectively validated in other
cohorts, this rule has the potential to standardize and improve efficiency
in the use of C-spine radiography in EDs.



Author/Article Information


Author Affiliations: Division of Emergency Medicine (Drs Stiell, Greenberg,
Reardon, and Worthington), Department of Medicine (Drs Stiell, Wells, and
Laupacis), Department of Epidemiology and Community Medicine (Drs Stiell and
Wells), Division of Neurosurgery (Dr Lesiuk), and Clinical Epidemiology Unit
(Drs Stiell and De Maio, and Mss Vandemheen and Clement), University of
Ottawa, Ottawa, Ontario; Department of Emergency Medicine, Queen's
University, Kingston, Ontario (Dr Brison); Division of Emergency Medicine,
University of Toronto, Toronto, Ontario (Drs Schull, Verbeek, Cass, and
Morrison); Division of Emergency Medicine, University of Western Ontario,
London (Drs Dreyer and Eisenhauer); Division of Emergency Medicine,
University of British Columbia, Vancouver (Drs McKnight and MacPhail).

Corresponding Author: Ian G. Stiell, MD, MSc, FRCPC, Clinical Epidemiology
Unit, F6, Ottawa Health Research Institute, 1053 Carling Ave, Ottawa,
Ontario, Canada K1Y 4E9 (e-mail: [log in to unmask] <mailto:[log in to unmask]> ).
Author Contributions: Study concept and design: Stiell, Wells, Vandemheen,
Lesiuk, Laupacis, McKnight, Verbeek, Brison, Dreyer, Eisenhauer, Greenberg,
MacPhail, Reardon.
Acquisition of data: Stiell, Vandemheen, Clement, McKnight, Verbeek, Brison,
Cass, Dreyer, Eisenhauer, Greenberg, MacPhail, Morrison, Worthington.
Analysis and interpretation of data: Stiell, Wells, De Maio.
Drafting of the manuscript: Stiell, Schull.
Critical revision of the manuscript for important intellectual content:
Stiell, Wells, Vandemheen, Clement, Lesiuk, De Maio, Laupacis, Schull,
McKnight, Verbeek, Brison, Cass, Dreyer, Eisenhauer, Greenberg, MacPhail,
Morrison, Reardon, Worthington.
Statistical expertise: Stiell, Wells, De Maio.
Obtained funding: Stiell, Wells, Vandemheen, Lesiuk, Laupacis.
Administrative, technical, or material support: Stiell, Vandemheen, Schull.
Study supervision: Vandemheen, Clement,
Funding/Support: This study was funded by peer-reviewed grants from the
Medical Research Council of Canada (MT-13700) and the Ontario Ministry of
Health Emergency Health Services Committee (11996N). Drs Stiell and Laupacis
hold Investigator Awards from the Canadian Institutes of Health Research.
Acknowledgment: We thank the following for their much appreciated
assistance: study nurses Erica Battram, RN, 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, and Jan Buchanan, RN; My-Linh Tran and Emily
Moen for data management; Irene Harris for manuscript preparation; and all
the physicians, nurses, and clerks at the study sites who voluntarily and
patiently assisted with case identification and data collection.




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Edward E. Rylander, M.D.
Diplomat American Board of Family Practice.
Diplomat American Board of Palliative Medicine.