Comparison of Point-of-Care Versus Laboratory Troponin Testing in an Emergency Department Setting

Abstract

Background: There have been concerns regarding troponin results accuracy between point-of-care (POC) testing preformed in an emergency department (ED) setting and laboratory testing. The purpose of this study was to compare the results of cardiac troponin I testing as concerns POC testing and laboratory analysis as a way to show that these results are interchangeable.

Methods: A retrospective chart review was performed from October 2012 through September 2013 to identify all patients who presented to the ED that received both a POC and laboratory troponin associated with the same blood draw.

Findings: A total of 189 patients met inclusion criteria. Three laboratory samples were hemolyzed and not available for comparison. Of the remaining 186 samples, when a positive cutoff value of 0.034 ng/mL was used: 37 POC tests were positive and 149 POC tests were negative, sensitivity 0.85 (95% confidence interval [CI] = 0.69-0.94), specificity 0.98 (95% CI = 0.94-0.99), positive predictive value 91.9% (95% CI = 77-97.9%), and negative predictive value 96% (95% CI = 91.1-98.4%). When a POC troponin positive cutoff value of 0.12 ng/mL was used: 20 POC tests were positive and 164 were negative: sensitivity 1.0 (95% CI = 0.8-1.0), specificity 0.99 (95% CI = 0.95-1.0), positive predictive value 91% (95% CI = 69-98.4%), and negative predictive value 100% (95% CI = 97.1-100%).

Discussion: In an ED setting; POC testing is accurate and correlates well with laboratory testing. Considering that the POC analysis takes a fraction of time to yield results, the validity of its data is important. The results of this study show that the POC system is a suitable test for rapid evaluation of patients presenting to the ED. This correlation increased with a higher testing positive cutoff value (0.12 versus 0.034 ng/mL). These data can assist the emergency physician with rapid identification of evidence of cardiac injury and be assured that the results are accurate.

Recommendations: POC lab testing should be considered whenever possible to provide the fastest troponin results.