Wound alpha defensin levels are significantly higher in patients with fracture related infection: A pilot, prospective cohort study.

Background: In absence of frank purulence, wound cultures represent 'gold-standard' for diagnosis of fracture related infection (FRI). However, these are time-intensive, and may be falsely negative, necessitating the need for accurate and rapid biomarker-based diagnosis. We conducted this study to determine the accuracy of 3 wound-based biomarkers for the diagnosis of FRI.

Methods: This was a prospective cohort study on adult patients who underwent an operative procedure for an upper or lower limb fracture. Wound fluid levels of alpha-defensin (AD), neutrophil elastase (NE) and IL-6 were evaluated on post-operative day 2, and patients were followed up for one month. Patients were categorized as cases (FRI) or controls (no FRI), on the basis of the consensus definition of FRI. Univariate analysis, along with receiver operating characteristic (ROC) analysis was performed.

Results: 48 patients were included. AD levels showed a 2.6-fold elevation in cases (n = 26, Median = 23.74 µg/ml) as compared to controls (n = 22, Median = 8.78 µg/ml). The area under the curve for this variable was 0.71 (95% Confidence Intervals = 0.56 - 0.86). The levels of NE and IL-6 were not significantly different between cases and controls.

Conclusion: Wound AD levels are significantly elevated in patients with FRI. However, these results need to be validated in a larger cohort of patients before it can be used as a biomarker of FRI.