Journal Club: Clinical Prediction Rules
Article Outline
Editor's Capsule Summary for Vaillancourt et al1 What is already known on this topic
Previous out-of-hospital studies indicate that selective spinal immobilization may miss patients with cervical injury.
What question this study addressed
Can paramedics apply the Canadian C-Spine Rule in alert, stable, cooperative, blunt-trauma patients to reserve spinal immobilization for high-risk patients while avoiding immobilization for low-risk patients?
What this study adds to our knowledge
In this 1,949-patient cohort, paramedics achieved 100% sensitivity and 38% specificity for important cervical fractures.
How this might change clinical practice
Use of the Canadian C-spine Rule by paramedics may safely avoid unnecessary spinal immobilization.
SEE RELATED ARTICLE, P. 663.
Discussion Points
A. Define the term “clinical prediction rule.”
B. Clinical prediction rules have been developed for many common emergency department (ED) complaints (eg, syncope, cervical spine injury, ankle pain). Physician scientists, including this Journal Club's authors, have differing opinions of the contribution of decision rules to physician decisionmaking. Discuss the pros and cons of clinical prediction rules and their effect on patient care.
A. Prediction modeling experts have established detailed methodological standards for the development and validation of a clinical prediction rule.2, 3 Your department's research director asks you to develop a prediction model for determining which patients with flulike symptoms need a chest radiograph to exclude pneumonia. Describe the recommended procedures for developing a new clinical prediction rule. What are some of the problems with the methodology described in 2 cited articles?B. Publications describing the development of a new clinical prediction rule often caution readers that the model must be validated before use in clinical practice. Why should clinical prediction rules be validated? Describe common internal and external validation techniques.C. The original Canadian C-Spine Rule was developed and validated for patients evaluated by physicians in the ED for possible cervical spine injury. This study examines the performance of a slightly modified rule when implemented by a different group of evaluators, specially trained paramedics. Describe what can happen when a prediction rule is enacted by a different group of evaluators than those for whom it was developed. Do you think the authors adequately accounted for this possibility?D. The criterion standard for the primary outcome, acute cervical spine injury, was defined as “any fracture dislocation, or ligamentous instability demonstrated by radiographic imaging.” Nearly half (1,126/2,393) of the eligible patients enrolled were not evaluated with cervical spine radiographs. What did the authors use as a surrogate measure for the criterion standard for these patients? The authors present the baseline characteristics for the patients with incomplete and complete outcome assessments. Why did the authors include this information in the appendix?
A. What is the estimated radiation exposure dose from a 2-view chest radiograph? Compare that dose to a cervical spine radiograph series and to a computed tomography (CT) scan of the cervical spine. What is the estimated lifetime risk of cancer attributable to these imaging studies?B. Many EDs perform “pan scan” CT imaging studies on trauma patients, regardless of whether the physical examination is concerning for injuries to each of the body regions. Why do many trauma surgeons advocate the use of whole-body CT imaging? What is the estimated radiation exposure and CT-related cancer risk from a single pan scan CT? Include in your answer how patient age and sex affect the overall risk of developing a cancer from ionizing radiation. How might cancer risk from imaging affect your management of trauma patients?
A. The rotating emergency medicine EMS resident recommends that the spine immobilization protocol be changed to include out-of-hospital application of the Canadian C-Spine Rule. The resident cites the Vaillancourt et al article and suggests that reducing unnecessary cervical spine immobilizations would result in decreased expenses and improved patient approval ratings. Would you amend the immobilization protocol according to the data?B. This study's cervical spine injuries incidence was smaller (0.6%) than that of previous reports (2%). This resulted in a large 95% confidence interval for the rule's sensitivity. How might the wide confidence intervals affect your decision to permit out-of-hospital cervical spine injury screening?
Reference
- The out-of-hospital validation of the canadian c-spine rule by paramedics. Ann Emerg Med. 2009;54:663–671
- . Methodologic standards for the development of clinical decision rules in emergency medicine. Ann Emerg Med. 1999;33:437–447
- . Clinical prediction rules: A review and suggested modifications of methodological standards. JAMA. 1997;277:488–494
Section editors: Tyler W. Barrett, MD; David L. Schriger, MD, MPH
Editor's Note: You are reading the twelfth installment of Annals of Emergency Medicine Journal Club. This bimonthly feature seeks to improve the critical appraisal skills of emergency physicians and other interested readers through a guided critique of actual Annals of Emergency Medicine articles. Each Journal Club will pose questions that encourage readers—be they clinicians, academics, residents, or medical students—to critically appraise the literature. During a 2- to 3-year cycle, we plan to ask questions that cover the main topics in research methodology and critical appraisal of the literature. To do this, we will select articles that use a variety of study designs and analytic techniques. These may or may not be the most clinically important articles in a specific issue, but they are articles that serve the mission of covering the clinical epidemiology curriculum.Journal Club entries are published in 2 phases. In the first phase, a list of questions about the article is published in the issue in which the article appears. Questions are rated “novice” (), “intermediate” (), and “advanced” () so that individuals planning a journal club can assign the right question to the right student. The answers to this journal club will be published in the April 2010 issue. US residency directors will have immediate access to the answers through the Council of Emergency Medicine Residency Directors Share Point Web site. International residency directors can gain access to the questions by going to http://www.emergencymedicine.ucla.edu/annalsjc/ and following the directions. Thus, if a program conducts its journal club within 5 months of the publication of the questions, no one will have access to the published answers except the residency director. The purpose of delaying the publication of the answers is to promote discussion and critical review of the literature by residents and medical students and discourage regurgitation of the published answers. It is our hope that the Journal Club will broaden Annals of Emergency Medicine's appeal to residents and medical students. We are interested in receiving feedback about this feature. Please e-mail journalclub@acep.org with your comments.
PII: S0196-0644(09)01553-4
doi:10.1016/j.annemergmed.2009.09.015
© 2009 Published by Elsevier Inc.
Refers to article:
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The Out-of-Hospital Validation of the Canadian C-Spine Rule by Paramedics
, 27 April 2009
