SLR - May 2019 - Ashley N. Arzadon

Role of Procalcitonin as a Predictor of Clinical Outcome in Acute Diabetic Foot Infections: A Prospective Study

Reference: Asirvatham AR, Menon U, Pavithran PV, Vasukutty JR, Kumar H, Bhavani N, et al. Role of Procalcitonin as a Predictor of Clinical Outcome in Acute Diabetic Foot Infections: A Prospective Study. Indian Journal of Endocrinology and Metabolism. 2019; 23, 122–7.

Scientific Literature Review

Reviewed By: Ashley N. Arzadon, DPM
Residency Program: Health Alliance Hospital, Kingston, NY

Podiatric Relevance: As physicians, it is imperative to educate patients living with diabetes on the importance of glycemic control and to refer patients to various specialties as secondary complications from poor diabetic control are common. Such complications include acute diabetic foot infections (DFIs), which can be life- or limb-threatening if the infection is severe. Podiatrists rely on various labs, including erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and white blood cell (WBC) count, in predicting the clinical outcome of acute DFIs. Procalcitonin (PCT), a precursor of calcitonin, is a highly sensitive test. Elevated PCT in cases with inflammatory response mechanisms are almost exclusively of bacterial origin. In this prospective study, authors compare ESR and CRP with PCT levels in predicting the outcome of acute DFI.

Methods: Two hundred fifty subjects presenting with acute DFIs to the Department of Endocrinology and Podiatry between January 2013 and December 2014 were included in this study. WBC count, ESR, CRP and PCT were performed on every patient after obtaining consent. Lab results were divided into two groups: bad and good outcomes. Other labs and imaging in this study included HbA1c, blood urea nitrogen, serum creatinine, liver function tests, fasting lipid profile, serum albumin, radiograph of the chest and infected foot and deep-tissue culture. Subjects were managed per hospital protocol. Clinical diagnosis of acute DFIs was based on the Infectious Disease Society of America (IDSA) 2012 guidelines and classification. Onset of acute DFIs were less than two weeks. Excluded were patients with type 1 diabetes mellitus, history of inflammatory disease and chronic bacterial infections. Clinical outcome was assessed based on mobility and morbidity status of the patient. Each subject had a one-month follow-up period.

Results: Old age, anemia, hyponatremia, hypoalbuminemia and elevated serum creatinine were risk factors for poor outcomes. Patients with history of cardiac failure, diabetic retinopathy, peripheral vascular disease (PVD), previous amputations and positive bone culture were predisposed to poor outcomes. Elevated WBC count, ESR, CRP and serum PCT were also associated with bad outcomes. A serum PCT of > 2 ng/ml, gangrene and sepsis were good predictors of bad outcomes in acute DFIs.

Conclusions: As physicians, it is important for us to monitor and to evaluate the progress/regress of a patient’s acute DFI. Typically, we monitor patients’ CMP, particularly blood urea nitrogen, and serum creatinine if a patient is receiving parenteral antibiotics. Additionally, we obtain CRP and WBC count as well as baseline ESR if osteomyelitis is of concern. In this study, PCT was considered a reliable marker of acute DFI and a better predictor of clinical outcome than the existing markers, ESR, CRP and WBC count. Consideration of gangrene, sepsis and/or elevated serum PCT may also be useful for clinicians in prognosticating clinical outcome, decision making and managing patients with acute DFIs. 

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