Abstract and Introduction
Introduction: Infected diabetic foot is the leading cause of hospital admissions for people with diabetes mellitus. Diabetic foot osteomyelitis (DFO) causes high morbidity and significant mortality. Current diagnostic tests for DFO are either expensive, invasive, or of low diagnostic yield.
Objective: The objective of the study was to determine whether serum levels of procalcitonin (PCT), an inflammatory marker, differ between DFO and diabetic foot ulcers without osteomyelitis (ie, cellulitis) as controls. The authors also aimed to assess the usefulness of PCT in diagnosing DFO.
Methods: A case-control study was designed comparing DFO with diabetic foot cellulitis as the control. Patients were classified as having osteomyelitis and cellulitis based on the International Working Group on the Diabetic Foot diagnostic criteria. Serum inflammatory markers PCT, adiponectin, C-reactive protein-1, osteoprotegerin (OPG), osteopontin (OPN), and interleukin 6 (IL-6) were analyzed in patients with DFO and controls.
Results: The median serum procalcitonin was significantly higher in the DFO group 108.5 pg/mL (range, 65.0–124.0 pg/mL) compared with 57.0 pg/mL (range, 37.2–77.0 pg/mL) controls (P = .02). Procalcitonin had a sensitivity of 79% compared with 50%, 63%, 66%, and 75% for adiponectin, OPG, OPN, and IL-6, respectively. Procalcitonin had a specificity of 70% compared with 50%, 71%, 70%, and 64%. Receiver operator characteristic curves showed a value of area under the curve of 0.73 and 0.77 for PCT and IL-6 compared with 0.4, 0.6, and 0.6 for adiponectin, OPG, and OPN, respectively.
Conclusions: In this study, procalcitonin was a useful diagnostic test for DFOs and provided distinct diagnostic discrimination between DFO from cellulitis. It may serve as a useful marker for diagnosing DFO. Further studies in a larger population are needed to verify the findings.
Infected diabetic foot soft tissue (cellulitis) and bone (osteomyelitis) are the leading causes of hospital admissions for people with diabetes mellitus and precede 90% of lower limb amputations. Diabetic foot osteomyelitis (DFO) with or without cellulitis causes high morbidity and significant mortality of 50% at 5 years after major amputation. These substantial issues become more prevalent with aging and are coupled with substantial economic burden. Each year in Australia, there are 5600 minor amputations (toe, midfoot) and 1500 major amputations (above/below knee) due to diabetes. Admission alone costs the hospital system $16 000 for a minor amputation and $34 000 for a major amputation, which increases stepwise with advancing age. Part of the reason for the high cost of care, morbidity, and mortality is due to the lack of a simple, effective test to differentiate the 2 common foot infections—cellulitis and osteomyelitis. Current diagnostic tests for the 2 conditions are either too expensive (magentic resonance imaging [MRI], bone scans), involve an invasive procedure (bone biopsy), limited availability (MRI/bone scan), or are of low diagnostic yield (x-ray).
Serum procalcitonin (PCT), a propeptide of the hormone calcitonin released by non-neuroendocrine parenchymal cells, was reported to be elevated in both cellulitis[5,6] and osteomyelitis,[7,8] with evidence showing lower values for cellulitis compared with osteomyelitis. Despite the apparent differences in serum levels of this biomarker in diabetic foot infections, to the authors' knowledge, no studies have been conducted to determine cutoff values of serum PCT to distinguish diabetic foot cellulitis from osteomyelitis. The aim of the study was to determine the clinical usefulness of serum PCT in diagnosing/differentiating diabetic foot cellulitis from osteomyelitis.
Wounds. 2021;33(7):192-196. © 2021 HMP Communications, LLC