SLR - July 2022 - Joseph S. Coppola, DPM
Reference: Vangaveti VN, Heyes O, Jhamb S, Haleagrahara N, Malabu UH. Usefulness of Procalcitonin in Diagnosing Diabetic Foot Osteomyelitis: A Pilot Study. Wounds. 2021 Jul;33(7):192-196. doi: 10.25270/wnds/2021.192196. PMID: 34237013.Level of Evidence: Level II
Scientific Literature Review
Reviewed By: Joseph S. Coppola, DPM
Residency Program: MetroWest Medical Center- Framingham, MA
Podiatric Relevance:
Diabetes Mellitus (DM) is a chronic, metabolic disease with increasing prevalence. Complications are common including soft tissue (cellulitis) and bony infections (osteomyelitis). These are detrimental to the healthcare system, complications are some of the leading causes of hospital admission for people with diabetes. In addition, they carry a high cost of care, partly due to the lack of quick and effective tests to differentiate between cellulitis and osteomyelitis. Procalcitonin (PCT) is a hormone released by nonneuroendocrine parenchymal cells which has previously been reported to be elevated in both osteomyelitis and cellulitis. However, serum levels are typically lower in cases of cellulitis ruling out more advanced infections such as osteomyelitis. No previous studies have been conducted to determine current values of serum PCT distinguishing between soft tissue and bone infections of the lower extremity. Therefore, this study aims to determine clinical usefulness of serum PCT to differentiate and support a diagnosis of diabetic foot cellulitis from osteomyelitis.
Methods:
A prospective, cohort study was performed at Moundsville University Hospital and Kirwan Community Health Center in Australia which looked at biomarkers of patients with diabetic foot osteomyelitis (group 1) and soft tissue infection of the foot (cellulitis, group 2, control). Inclusion criteria included patients with type 2 DM, aged 18 years or older, and moderate/severe ulcer based on IDSA classifications. Exclusion criteria included patients who had planned surgical intervention, clinically significant lower extremity ischemia (ABI less than 0.65), ulcer of nondiabetic pathophysiology, currently taking immunosuppressive therapies, organ and/or hematological malignancies, or end-stage renal disease requiring dialysis. Antibiotics were administered after obtaining diagnostic blood and tissue samples. The diabetic foot osteomyelitis group was defined by intraoperative bone sampling with histologic findings, presence of probable bone underlying ulcer or by imaging such as radiographs or MRI. Morning fasting venous blood samples were obtained for procalcitonin and other inflammatory markers such as IL-6. All categorical variables were tested, and ROC curves were generated
Results:
Thirty-seven (37) participants were enrolled in the study with 19 participants in the osteomyelitis group and 18 participants in the control group. Both groups had a similar mean age, percentages of participants taking oral hypoglycemic agents and insulin as well as similar percentages of nontraumatic lower limb amputations (59 percent & 74 percent respectively). Fifty-seven (57) ulcerations were studied comprising 28 ulcers in the osteomyelitis group and 29 ulcers in the control group. Seventy-eight (78) percent of the osteomyelitis group had forefoot ulcers and 86 percent of the control group. There was no statistical significance regarding differences for alcohol consumption and smoking between the groups. Mean serum levels of PCT for DFO group were 108.5 pg/ml and for control 57 pg/ml with a sensitivity of 79 percent and specificity of 70 percent. For IL-6, DFO group was 22 pg/ml and for control 3.5 pg/ml with a sensitivity of 75 percent and specificity of 64 percent. Both values were deemed significant.
Conclusions:
In summary, the authors conclude a significantly high level of PCT is an additional method in aiding the clinician when diagnosing osteomyelitis versus solely a soft tissue infection in the DM population. This has been validated in other studies with similar findings regarding sensitivity and specificity of PCT as a marker for bone infection. The current study will augment the diagnostic toolkit in aiding the clinician to make a prompt and appropriate diagnosis while maintaining cost effectiveness. Despite the limited sample size, these findings are consistent with similar studies expressing the validity of PCT in clinical practice to rule out/in osteomyelitis. Further studies, on a larger scale, are warranted to obtain more reliable findings.