Journal Club: Is the Golden Hour Tarnished? Registries and Multivariable Regression
Article Outline
Editor's Capsule Summary for Newgard et al1
What is already known on this topic
The “golden hour” concept in trauma is pervasive despite little evidence to support it.
What question this study addressed
Is there an association between various emergency medical services (EMS) intervals and inhospital mortality in seriously injured adults?
What this study adds to our knowledge
In 3,656 injured patients with substantial perturbations of vital signs or mental status, transported by 146 EMS agencies to 51 trauma centers across North America, no association was found among any EMS interval and mortality.
How this might change clinical practice
This study suggests that in our current out-of hospital and emergency care system time may be less crucial than once thought. Routine lights-and-sirens transport for trauma patients, with its inherent risks, may not be warranted.
Discussion Points
A. Explain how missing data might bias a study's conclusions. Include in your answer a discussion about how missing data on patients' initial vitals signs might have altered this study's conclusion.B. Describe what the term “pattern of missingness” means. Why is it important to understand whether data are missing at random or not?
C. There are multiple methods for handling missing data. Discuss the advantages and disadvantages of some of the more common methods, including excluding cases with missing data, treating binary categorical as yes/no/missing rather than yes/no, carrying forward the last known value, assigning the sample mean for missing data, and performing multiple imputation.D. The most successful investigators design studies and data collection forms to minimize the potential for missing data. If you were planning a large registry study, what design features might you incorporate to decrease the amount of missing data?
A. Conduct a brief review of the medical literature and lay press, tracing the introduction of medical helicopter transport to the current debates over patient and flight personnel safety.B. According to your review for question 2.A and the conclusions from the Newgard et al1 article, what is your opinion on the proper role for medical helicopter transport in trauma resuscitations? Should medical helicopter transport be used when anticipated ground transport times are greater than 60 minutes, 90 minutes, 120 minutes, or none of the above? What additional patient or emergency medical services (EMS) system factors must be considered when determining the best transport mode for a critically ill trauma patient?C. The Federal Emergency Treatment and Active Labor Act (EMTALA) requires that the transferring physician “ensure that the transfer of an unstabilized individual is effected through qualified personnel and transportation equipment, including the use of medically appropriate life support measures.”2 Discuss how EMTALA might affect the decisions on transporting a trauma patient to the regional trauma center. What other measures does EMTALA require of hospitals and physicians when transferring or accepting patients?
A. One advantage of a registry study is that one can enroll large numbers of patients, thereby increasing precision. Unfortunately, registries are subject to certain biases that can result in erroneous conclusions. Describe the advantages and limitations of this study design. What are some potential biases of registries? What types of quality assurance measures did the investigators incorporate into the study's operating procedures to minimize these limitations?B. Explain in layman's terms what multivariable regression is. Why is multivariable regression especially important to biomedical research? Contrast a fully explicated model (one that includes all interaction terms) versus one that has no interaction terms. How do logistic regression, linear regression, and Cox proportional hazards survival regression analyses differ in their outcome variables and output? What are some of the assumptions and limitations associated with each type of regression analysis?C. In the “Limitations” section, the authors mention that they used a fixed-effect model to account for the “likely variation in field care, hospital care, and injury characteristics between sites, EMS agencies, and hospitals.” Define what a fixed-effect model is and how it differs from a random-effects model.
In your opinion, what are the most important conclusions from this article? How might these conclusions affect EMS transport of trauma patients in urban and rural settings? How might the limitations mentioned by the authors affect your medical control recommendations for patient transport by medical helicopter versus ground transport with or without lights and sirens?
References
- Emergency medical services intervals and survival in trauma: assessment of the “golden hour” in a north american prospective cohort. Ann Emerg Med. 2010;55:235–246
- . State operations manual (Appendix v--interpretive guidelines & responsibilities of medicare participating hospitals in emergency cases). http://www.cms.hhs.gov/manuals/Downloads/som107ap_v_emerg.pdfAccessed December 22, 2009
Section editors: Tyler W. Barrett, MD; David L. Schriger, MD, MPH
SEE RELATED ARTICLE, P. 235.
Editor's Note: You are reading the 14th 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 August 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(10)00003-X
doi:10.1016/j.annemergmed.2010.01.001
© 2010 Published by Elsevier Inc.
Refers to article:
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Emergency Medical Services Intervals and Survival in Trauma: Assessment of the “Golden Hour” in a North American Prospective Cohort
, 24 September 2009
