Does Everything That's Counted Count? Value of Inflammatory Markers for Following Therapy and Predicting Outcome in Diabetic Foot Infection

To assess the severity of inflammation associated with diabetic foot infection (DFI), values of inflammatory markers such as white blood count (WBC), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), and neutrophil to lymphocyte ratio (NLR) are often measured and tracked over time. It remains unclear if these markers can aid the clinician in the diagnosis and management of DFI, and ensure more rational use of antibiotics. Hospitalized adult patients (n = 379) with DFI were retrospectively assessed for abnormal inflammatory markers, correlation between values of inflammatory markers, and clinical diagnosis on initial admission and on last follow-up. At admission, WBC, ESR and NLR were each elevated in patients with osteomyelitis and only ESR was significantly elevated in patients with soft tissue infection only. Only WBC was significantly elevated in patients with osteomyelitis compared with uninfected diabetic feet on last follow-up. Considering the predictive performance of these inflammatory markers, they demonstrated excellent positive predictive value at admission, and excellent negative predictive value at the last follow-up visit. Moreover, the number of elevated markers was further associated with probability of infection both at admission and last follow-up.