Novel Biomarkers: Help or Hindrance to Patient Care in the Emergency Department?
Article Outline
Editor's Capsule Summary for Shapiro et al1 What is already known on this topic
Acute kidney injury is common in severe infection. At present, there are no biomarkers that accurately detect its presence before increase of the creatinine level.
What question this study addressed
This 661-patient observational study tested the diagnostic performance of neutrophil gelatinase–associated lipocalin (NGAL) to detect acute kidney injury in emergency department patients with suspected infection.
What this study adds to our knowledge
Plasma concentrations of NGAL greater than 150 ng/dL were 96% sensitive and 51% specific for acute kidney injury occurring within the first 72 hours of hospitalization.
How this might change clinical practice
These preliminary results should not change clinical practice but suggest that NGAL may be useful for identifying patients at risk for acute kidney injury.
SEE RELATED ARTICLE, P.52.
Discussion Points
A. Define the term biomarker. How might biomarkers assist in the risk stratification of patients with chest pain suggestive of acute pulmonary embolism? Consider using the Bayesian approach to answering this clinical question.
B. Why do you think that there is a frenzy of biomarker research?C. Discuss some of the benefits and limitations of using biomarkers to direct patient care in the emergency department (ED). Have studies proven that biomarkers perform better than physician gestalt and result in better patient outcomes?D. Compare the language of the conclusion of the abstract and the conclusion of the capsule summary that the Annals of Emergency Medicine editor prepared. What are the differences between them? Why do you think they differ?A. Discuss how the sensitivity and specificity of NGAL to predict acute kidney injury change as the cut point is decreased from 400 ng/mL to 150 ng/mL.B. According to existing knowledge, would you choose 150 ng/mL or 400 ng/mL as the optimal cut point for NGAL to predict acute kidney injury in ED patients with a suspected infection? Why?C. If an inexpensive therapy (eg, actual treatment cost of $100/patient) existed that could prevent acute kidney injury when administered in the ED and had minimal risk for toxicity, what cut point for NGAL would you choose? Would your cut point change if the treatment cost $10,000/patient and required intensive care monitoring?A. Review the recommended study design criteria for evaluating a novel biomarker. What type of study design is preferred for prognostic research? Why is it important for investigators to clearly define the outcome measure a priori? What are the advantages and limitations of using a composite outcome when evaluating a new biomarker?B. Hlatky et al2 suggest that the first test of a biomarker is to determine whether it differentiates subjects with and without the outcome. What additional evaluations are required to prove the biomarker's value in patient care?C. Shapiro et al1 define acute kidney injury as an increase in creatinine level of more than 0.5 mg/dL or the acute need for renal replacement therapy within 72 hours. Can you figure out how many of the 24 patients defined as having acute kidney injury had a peak creatinine level that exceeded 1.5 mg/dL? 2.0 mg/dL? Do you think that it would be important to know the peak creatinine levels of the patients deemed to have acute renal failure?
D. Shapiro et al1 suggest that the use of NGAL for the prediction of acute kidney injury in ED patients with suspected infection may be most beneficial for patients with a normal initial serum creatinine level. In this study, 13 of the 558 patients (2.3%) with an initial serum creatinine level less than or equal to 2.0 mg/dL subsequently met the definition for acute kidney injury. Discuss how the prevalence of acute kidney injury would factor into the cost-effectiveness of NGAL in this population compared with a different population with a higher prevalence of disease..4A. Conduct a brief review of the medical literature, tracing the progress of NGAL from initial discovery to current investigations as an early predictor of acute kidney injury..4B. According to your review for question 4A, did the previous studies adhere to the recommended procedures advocated by Hlatky et al?2 Would you advocate to your ED administration to invest in the NGAL point-of-care testing according to the available literature?
References
- The diagnostic accuracy of plasma neutrophil gelatinase–associated lipocalin (NGAL) in the prediction of acute kidney injury in emergency department patients with suspected sepsis. Ann Emerg Med. 2010;56:52–59
- Criteria for evaluation of novel markers of cardiovascular risk: a scientific statement from the American Heart Association. Circulation. 2009;119:2408–2416
Section editors: Tyler W. Barrett, MD, MSCI; David L. Schriger, MD, MPH
Editor's Note: You are reading the 16th 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 December 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)00447-6
doi:10.1016/j.annemergmed.2010.04.026
© 2010 Published by Elsevier Inc.
Refers to article:
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The Diagnostic Accuracy of Plasma Neutrophil Gelatinase–Associated Lipocalin in the Prediction of Acute Kidney Injury in Emergency Department Patients With Suspected Sepsis
, 05 April 2010
