Discriminative Accuracy of Procalcitonin and Traditional Biomarkers in Pediatric Acute Musculoskeletal Infection

Objectives: Septic arthritis (SA) is responsible for 20% of pediatric musculoskeletal infections (MSKI) and can have significant consequences. Early detection of SA is critical, and procalcitonin (PCT) has emerged as a promising biomarker. This study assessed the test performance of PCT and traditional biomarkers for suspected SA.

Methods: We conducted a prospective study at two pediatric emergency departments (ED). Data collected measured serum levels of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), white blood cell (WBC) count, and PCT. Box and whisker plots were generated to compare the of the biomarkers by positive MSKI or a non-MSKI diagnosis. The diagnostic performance of biomarkers was examined using the area under the receiver operating characteristic curve (AUC), and optimal cut -points were identified using the Liu method.

Results: Procalcitonin performed reasonably well for detection of MSKI (AUC, 0.72; confidence interval [95% CI], 0.59-0.84). However, CRP and ESR performed better (AUC, 0.88 and 0.78, respectively). White blood cell count was not predictive of MSKI. Patients with a PCT value >0.1 ng/mL, ESR values >19.5 mm/h, and a temperature higher than 99.0°F were more than twice as likely to have acute MSKI. A high CRP level was most predictive of acute MSKI, and patients with levels >2.38 mg/dL were 3.5 times more likely to have acute MSKI.

Conclusions: Procalcitonin is a potential biomarker for the clinical differential of MSKI in the pediatric ED. Additional research is warranted to establish the optimal diagnostic level for PCT, to increase sample size, and to examine any impact on cost.