ESR and CRP Testing in an Urban Emergency Department

OBJECTIVES: Pediatricians in the Emergency Department frequently evaluate febrile children. To help identify the cause of fever and assess the severity of the underlying condition, practitioners often utilize erythrocyte sedimentation rate and C-reactive protein testing. While these markers of inflammation are deeply embedded in the practice of pediatrics, they were each developed more than 90 years ago, and their utility to current clinical practice is not well characterized. METHODS: We conducted a 1-year retrospective study of children who underwent CRP and ESR testing at an urban Children's Hospital. We recorded and analyzed indications for testing, concordance between testing methods and metrics, including admission status and test performance, as reflected by sensitivity, specificity, and likelihood ratios. RESULTS: ESR and CRP tests were frequently ordered in patients with clinically evident diagnoses. There were no cases of occult bacteremia, and patients with bacteremia typically had presentations indicative of bacterial infection. CRP was superior to ESR as a predictor of bacterial infection; however, the positive likelihood ratio was only 2.1. Combined testing was ordered for 39.4% of all CRP tests, and there was a high concordance (69.9%) between CRP and ESR testing. Combined testing offered limited incremental value for the detection of bacterial infections. CONCLUSIONS: CRP and ESR testing are currently overused in our Pediatric Emergency Department, providing limited diagnostic value while adding unnecessary hospital cost. Combined CRP and ESR testing provides limited incremental value. Stewardship of these testing modalities and an active reconsideration of how these tests are employed should be considered.