Procalcitonin and IL-6 Predict Early Infection in Open Fracture Patients Undergoing Definitive Fixation

Fracture-related infections (FRI) are a significant complication, particularly in open fractures, leading to prolonged morbidity and increased healthcare costs. Current diagnostic methods for FRI often rely on clinical signs, which typically manifest once the infection is already established, delaying crucial intervention. Biomarkers like procalcitonin (PCT) and interleukin-6 (IL-6) have demonstrated utility in detecting periprosthetic joint infections (PJI), suggesting a potential role in early FRI diagnosis. This study investigates if these biomarkers can predict FRI in patients with open fractures undergoing staged, early conversion from external to definitive internal fixation, addressing a critical gap in timely infection detection.

This prospective cohort study enrolled 86 patients with open long bone fractures initially treated with external fixation. Patients were included if they underwent definitive internal fixation within 2 weeks of primary external fixation. Serum IL-6 and PCT levels were measured at multiple time points: on day 0, day 3, and day 7 following primary external fixator application, and again 1 day prior to the definitive internal fixation surgery. The study determined the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), likelihood ratios (LR+ and LR-), diagnostic accuracy, and area under the receiver operating characteristic (AUC-ROC) curve for both biomarkers, individually and in combination, to predict subsequent FRI.

Out of the 86 patients initially enrolled, 10 patients developed an infection before definitive fixation. An additional 28 patients were excluded due to complications like wound dehiscence or pin-tract infection, or being unfit for a second surgery. Ultimately, 48 patients proceeded to definitive internal fixation, with 5 of these developing infections during follow-up. This resulted in a total of 15 patients being classified into the infection cohort. The analysis revealed that Procalcitonin (PCT) demonstrated better sensitivity compared to IL-6 alone or the IL-6 and PCT combination. Conversely, the combined use of IL-6 and PCT yielded superior specificity. Both biomarkers individually exhibited poor positive predictive value (PPV) but showed good negative predictive value (NPV). > When used in combination, IL-6 and PCT achieved good diagnostic accuracy and a better area under the curve (AUC) than either biomarker used alone, suggesting enhanced predictive power for FRI when assessed together.