Concentration standardization improves the capacity of drainage CRP and IL-6 to predict surgical site infections.

IMPACT STATEMENT: The ability to predict surgical site infections (SSIs) early would be advantageous. Previous studies have investigated the use of inflammatory factors in fluids drained from surgical sites to predict SSI, but the diagnostic efficacy of this method requires improvement. Baseline levels of inflammatory factors vary between individuals, but this variation tends to differ in patients with and without SSIs. Therefore, we standardized subsequently acquired concentrations of interleukin 6 and C-reactive protein in fluids drained from surgical sites by dividing them by the concentrations determined at day 1 to preclude the confounding effects of differences in baseline levels. The standardized concentrations had higher predictive efficacy than the absolute concentrations. Standardizing the data rendered SSI prediction more precise and practical in a diverse group of real patients. This translational study suggests that inflammatory factors in fluid drained from injury sites are promising tools for the prediction of SSI in the clinic.