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 κ coefficient, logistic regression
analysis, and χ2 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.
More than 1 million patients with blunt trauma and potential cervical
spine (C-spine) injury are treated each year in US emergency departments (EDs).1,2 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
Due to concerns about potentially disabling spinal injuries, most clinicians
make liberal use of C-spine radiography.6-9
Nevertheless, such practice is inefficient—more than 98% of C-spine
radiographs are negative for fracture.10-16
Furthermore, there is considerable practice variation among well-trained emergency
physicians, with radiography rates ranging as much as 6-fold.17
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.18,19
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 decisions—for example, the use of radiography for patients
with ankle or knee injuries.20-23
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.24,25
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 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.
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
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
The interobserver agreement for each variable was measured by calculating
the κ coefficient, the proportion of potential agreement beyond chance,
along with 95% confidence intervals (CIs).29,30 κ
Values 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 χ2 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 (κ>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).31,32
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.33,34 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%.
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). 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 and Table 3 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 also shows
the interobserver agreement for the primary clinical variables from those
patients (n = 150) examined by 2 physicians.
Logistic regression analysis (Table
4) 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). 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). 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.
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.12,15,16
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 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.3,7,35-37
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 Other trauma clinicians agree that a selective approach
is ideal but do not give clear recommendations.39-41
Most authors suggest that radiography may not be required in alert patients
with no pain or tenderness of the neck.42-46
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.47,48
According to Neifeld and colleagues,13 "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
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.26,48,50
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 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.24,25,52-54
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 bias—the 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 Based on our studies that show large reductions in
the use of ankle radiography after the implementation of the Ottawa Ankle
Rules,20,21 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.
1.McCaig LF. National Hospital Ambulatory Medical Care Survey: 1992 emergency department
summary.
Adv Data.1994;245:1-12.Google Scholar 2.National Center for Health Statistics. National Hospital Ambulatory Medical Care Survey 1992. Hyattsville, Md: National Center for Health Statistics; 1994.
3.Reid DC, Henderson R, Saboe L, Miller JD. Etiology and clinical course of missed spine fractures.
J Trauma.1987;27:980-986.Google Scholar 4.Diliberti T, Lindsey RW. Evaluation of the cervical spine in the emergency setting: who does
not need an x-ray?
Orthopedics.1992;15:179-183.Google Scholar 5.Bachulis BL, Long WB, Hynes GD, Johnson MC. Clinical indications for cervical spine radiographs in the traumatized
patient.
Am J Surg.1987;153:473-478.Google Scholar 6.McNamara RM, Heine E, Esposito B. Cervical spine injury and radiography in alert, high-risk patients.
J Emerg Med.1990;8:177-182.Google Scholar 7.McKee TR, Tinkoff G, Rhodes M. Asymptomatic occult cervical spine fracture: case report and review
of the literature.
J Trauma.1990;30:623-626.Google Scholar 8.Roberge RJ, Wears RC, Kelly M.
et al. Selective application of cervical spine radiography in alert victims
of blunt trauma: a prospective study.
J Trauma.1988;28:784-788.Google Scholar 9.Jacobs LM, Schwartz R. Prospective analysis of acute cervical spine injury: a methodology
to predict injury.
Ann Emerg Med.1986;15:44-49.Google Scholar 10.Fischer RP. Cervical radiographic evaluation of alert patients following blunt
trauma.
Ann Emerg Med.1984;13:905-907.Google Scholar 11.Gbaanador GBM, Fruin AH, Taylon C. Role of routine emergency cervical radiography in head trauma.
Am J Surg.1986;152:643-648.Google Scholar 12.Bayless P, Ray VG. Incidence of cervical spine injuries in association with blunt head
trauma.
Am J Emerg Med.1989;7:139-142.Google Scholar 13.Neifeld GL, Keene JG, Hevesy G, Leikin J, Proust A, Thisted RA. Cervical injury in head trauma.
J Emerg Med.1988;6:203-207.Google Scholar 14.Vandemark RM. Radiology of the cervical spine in trauma patients: practice pitfalls
and recommendations for improving efficiency and communication.
AJR Am J Roentgenol.1990;155:465-472.Google Scholar 15.Roberge RJ. Facilitating cervical spine radiography in blunt trauma.
Emerg Med Clin North Am.1991;9:733-742.Google Scholar 16.Daffner RH. Cervical radiography in the emergency department: who, when, how extensive?
J Emerg Med.1993;11:619-620.Google Scholar 17.Stiell IG, Wells GA, Vandemheen K.
et al. Variation in emergency department use of cervical spine radiography
for alert, stable trauma patients.
CMAJ.1997;156:1537-1544.Google Scholar 18.Moloney TW, Rogers DE. Medical technology: a different view of the contentious debate over
costs.
N Engl J Med.1979;301:1413-1419.Google Scholar 19.Angell M. Cost containment and the physician.
JAMA.1985;254:1203-1207.Google Scholar 20.Stiell IG, McKnight RD, Greenberg GH.
et al. Implementation of the Ottawa Ankle Rules.
JAMA.1994;271:827-832.Google Scholar 21.Stiell IG, Wells G, Laupacis A.
et al. for the Multicentre Ankle Rule Study Group. A multicentre trial to introduce the Ottawa ankle rules for the use
of radiography in acute ankle injuries.
BMJ.1995;311:594-597.Google Scholar 22.Stiell IG, Greenberg GH, Wells GA.
et al. Prospective validation of a decision rule for the use of radiography
in acute knee injuries.
JAMA.1996;275:611-615.Google Scholar 23.Stiell IG, Wells GA, Hoag RA.
et al. Implementation of the Ottawa Knee Rule for the use of radiography in
acute knee injuries.
JAMA.1997;278:2075-2079.Google Scholar 24.Laupacis A, Sekar N, Stiell IG. Clinical prediction rules: a review and suggested modifications of
methodological standards.
JAMA.1997;277:488-494.Google Scholar 25.Stiell IG, Wells GA. Methodologic standards for the development of clinical decision rules
in emergency medicine.
Ann Emerg Med.1999;33:437-447.Google Scholar 26.Hoffman JR, Mower WR, Wolfson AB, Todd KH, Zucker MI. Validity of a set of clinical criteria to rule out injury to the cervical
spine in patients with blunt trauma.
N Engl J Med.2000;343:94-99.Google Scholar 27.Stiell IG, Lesiuk H, Vandemheen K.
et al. Obtaining consensus for a definition of "Clinically Important Cervical
Spine Injury" in the CCC Study [abstract 196].
Acad Emerg Med.1999;6:435.Google Scholar 28.Stiell IG, Vandemheen K, Brison R.
et al. Validity evaluation of the cervical spine injury proxy outcome assessment
tool in the CCC Study [abstract 195].
Acad Emerg Med.1999;6:434.Google Scholar 29.Kramer MS, Feinstein AR. Clinical biostatistics, LIV: the biostatistics of concordance.
Clin Pharmacol Ther.1981;29:111-123.Google Scholar 30.Landis JR, Koch GG. The measurement of observer agreement for categorical data.
Biometrics.1977;33:159-174.Google Scholar 31.Ciampi A, Hogg SA, McKinney S, Thiffault J. RECPAM: a computer program for recursive partition and amalgamation
for censored survival data and other situations frequently occurring in biostatistics,
I: methods and program features.
Comput Methods Programs Biomed.1988;26:239-256.Google Scholar 32.Friedman JH. A recursive partitioning decision rule for nonparametric classification.
IEEE Trans Comput.1977;16:404-408.Google Scholar 33.Efron B. The Jackknife, the Bootstrap and Other Resampling
Plans. Philadelphia, Pa: Society for Industrial and Applied Mathematics;
1982.
34.Efron B, Tibshirani R. An Introduction to the Bootstrap. New York, NY: Chapman & Hall; 1993.
35.Changaris DG. Cervical spine films, cost, and algorithms.
Am J Surg.1987;153:478.Google Scholar 36.Woodring JH, Lee C. Limitations of cervical radiography in the evaluation of acute cervical
trauma.
J Trauma.1993;34:32-39.Google Scholar 37.Davis JW, Phreaner DL, Hoyt DB, Mackersie RC. The etiology of missed cervical spine injuries.
J Trauma.1993;34:342-346.Google Scholar 38. Advanced Trauma Life Support Instructor Manual. 5th ed. Chicago, Ill: American College of Surgeons; 1993.
39.Hills MW, Deane SA. Head injury and facial injury: is there an increased risk of cervical
spine injury?
J Trauma.1993;34:549-554.Google Scholar 40.Frye G, Wolfe T, Knopp R, Lesperance R, Williams J. Intracranial hemorrhage as a predictor of occult cervical-spine fracture.
Ann Emerg Med.1994;23:797-801.Google Scholar 41.Williams J, Jehle D, Cottington E, Shufflebarger C. Head, facial, and clavicular trauma as a predictor of cervical-spine
injury.
Ann Emerg Med.1992;21:719-722.Google Scholar 42.Roberge RJ, Wears RC. Evaluation of neck discomfort, neck tenderness, and neurologic deficits
as indicators for radiography in blunt trauma victims.
J Emerg Med.1992;10:539-544.Google Scholar 43.Roth BJ, Martin RR, Foley K, Barcia PJ, Kennedy P. Roentgenographic evaluation of the cervical spine: a selective approach.
Arch Surg.1994;129:643-645.Google Scholar 44.Domeier RM, Evans RW, Swor RA, Frederiksen SM. Prospective validation of prehospital spinal clearance criteria [abstract
053].
Acad Emerg Med.1995;2:355-356.Google Scholar 45.Rosen P, Barkin RM, Danzl DF.
et al. Emergency Medicine: Concepts and Clinical Practice. 4th ed. Toronto, Ontario: CV Mosby Co; 1998.
46.Tintinalli JE, Kelen GD, Stapczynski JS. Emergency Medicine: A Comprehensive Study Guide. 5th ed. Toronto, Ontario: McGraw-Hill Inc; 2000.
47.McNamara RM, O'Brien MC, Davidheiser S. Post-traumatic neck pain: a prospective and follow-up study.
Ann Emerg Med.1988;17:906-911.Google Scholar 48.Hoffman JR, Schriger DL, Mower W, Luo JS, Zucker M. Low-risk criteria for cervical-spine radiography in blunt trauma: a
prospective study.
Ann Emerg Med.1992;21:1454-1460.Google Scholar 49.Graham ID, Stiell IG, Laupacis A, O'Connor AM, Wells GA. Emergency physicians' attitudes toward the use of clinical decision
rules for radiography.
Acad Emerg Med.1998;5:134-140.Google Scholar 50.Hoffman JR, Wolfson AB, Todd K, Mower WR. Selective cervical spine radiography in blunt trauma: methodology of
the National Emergency X-Radiography Utilization Study(NEXUS).
Ann Emerg Med.1998;32:461-469.Google Scholar 51.Stiell IG, McKnight RD, Wells GA.
et al. Application of the Nexus Low-Risk Criteria for cervical spine radiography
in Canadian emergency departments [abstract 417].
Acad Emerg Med.2000;7:566.Google Scholar 52.Wasson JH, Sox HC, Neff RK, Goldman L. Clinical prediction rules: application and methodological standards.
N Engl J Med.1985;313:793-799.Google Scholar 53.Feinstein AR. Clinimetrics. New Haven, Conn: Yale University Press; 1987.
54.McGinn TG, Guyatt GH, Wyer PC, Naylor CD, Stiell IG, Richardson WS. Users' guides to the medical literature, XXII: how to use articles
about clinical decision rules.
JAMA.2000;284:79-84.Google Scholar 55.Graham ID, Stiell IG, Laupacis A.
et al. Emergency physicians' views on the use of computed tomography and cervical
spine radiography. In: Proceedings of the 14th Annual Meeting of the International Society
of Technology Assessment in Health Care; June, 7-10 1998; Ottawa, Ontario.