Calcitonin Gene-Related Peptide for Identifying Pediatric Bacterial Musculoskeletal Infections: A Prospective,...

Bacterial musculoskeletal infections (MSKIs) can be challenging to diagnose. We compared the accuracy of calcitonin gene-related peptide (CGRP), a neuropeptide which is transcribed from the same gene as procalcitonin, to procalcitonin for the diagnosis of a MSKI in children.

We conducted a prospective cohort study of patients 21 years old or younger who underwent evaluation for MSKIs at one of 3 emergency departments. Our primary outcome was a MSKI, defined as septic arthritis, osteomyelitis, or pyomyositis. We used a Spearman correlation coefficient to measure the association between serum CGRP and procalcitonin and compared the diagnostic accuracy using area under the receiver operating characteristic curve (AUC) analysis.

Of the 200 enrolled patients, 33 (17%) had a MSKI. Overall, median serum CGRP level did not differ between patients with and without a MSKI (13.5 pg/mL MSKI vs 10.9 pg/mL no MSKI; difference: 2.6, 95% CI: -0.6, 5.8), while PCT was higher in patients with a MSKI (0.12 ng/mL MSKIs vs 0.04 ng/mL no MSKI; difference: 0.08, 95% CI: 0.03 to 0.13). CGRP and PCT levels were not correlated (Spearman rank coefficient: -0.01, 95% CI: -0.15 to 0.13). CGRP had a lower AUC than procalcitonin [0.57, 95% CI: 0.47 to 0.66 CGRP vs 0.78, 95% CI: 0.69 to 0.87 PCT, P < 0.01].

Although biochemically related, CGRP was not correlated with procalcitonin in children undergoing evaluation for a MSKI. Our exploratory pilot highlights the ongoing need for novel biomarkers for the accurate and timely identification of children with a MSKI.