SLR - January 2023 - Archana Krishnan, PGY-2
Title: A new inflammatory marker of clinical and diagnostic importance in diabetic foot infection: Systemic immune-inflammation indexReference: Ozer Balin S, Ozcan EC, Uğur K. A New Inflammatory Marker of Clinical and Diagnostic Importance in Diabetic Foot Infection: Systemic Immune-Inflammation Index. Int J Low Extrem Wounds. 2022 Oct 11:15347346221130817. doi: 10.1177/15347346221130817. Epub ahead of print. PMID: 36221931.
Level of Evidence: Level 3, retrospective cohort study
Scientific Literature Review
Reviewed by: Archana Krishnan, PGY-2
Residency Program: LECOM/Millcreek Community Hospital, Erie, PA
Podiatric Relevance: This article explores the use of inflammatory biomarkers for the diagnosis of osteomyelitis. Although bone biopsy is the current gold standard for diagnosis of osteomyelitis, there are clinical situations in which using these inflammatory markers may facilitate early diagnosis as well as differentiation between cellulitis and osteomyelitis. The purpose of this study is to evaluate the significance of inflammatory markers including Systemic Immune-Inflammation Index (SII), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and procalcitonin (PCT) in the diagnosis of osteomyelitis secondary to diabetic foot infections.
Methods: The study included 247 patients with type 2 diabetes who were divided into two groups. Group 1 had 151 patients and included patients with osteomyelitis. Group 2 had 96 patients and included patients with soft tissue infections only. The patients were chosen retrospectively from those admitted to the endocrinology ward between January 2020 and February 2022 with moderate to severe diabetic foot infections.
Results: The patients in Group 1 were diagnosed with osteomyelitis based on clinical findings, radiographic alterations, MRI, positive probe to bone test. These patients all also had confirmed osteomyelitis based on positive bone culture. The ESR, CRP, PCT, Platelet-lymphocyte ration (PLR), Neutrophil-lymphocyte ratio (NLR) and SII were obtained for both groups of patients. The SII was calculated using the following formula: platelet x (neutrophils/lymphocytes). The PLR and NLR were calculated using ration of neutrophils to lymphocytes and platelets to lymphocytes respectively. The SII, NLR, PLR, WBC, ESR, CRP and PCT levels were significantly higher in patients in Group 1. The rate of minor and major amputation was 11% and 69% approximately, while there were only two patients in group 2 who underwent minor amputation. The SII was moderately and positively correlated with ESR, CRP and PCT in patients with osteomyelitis.
Conclusions: The positive correlation between SII and ESR, CRP, and PCT in patients with osteomyelitis shows that SII may be an auxiliary marker in the diagnosis of osteomyelitis. The authors suggest that the use of these inflammatory markers may lead to early diagnosis of osteomyelitis in settings in which bone culture is not readily available. This is a small, retrospective study with a small size, and thus the results need to be further investigated with larger prospective studies. ESR and CRP have been reliably used in as indicators of osteomyelitis. The additional markers discussed in this article provide more data when analyzing patient that may lend themselves to a positive diagnosis of osteomyelitis. The relevance of this study in patient care is that these biomarkers can be used to evaluate a patient’s prognosis, however, bone biopsy continues to be the gold standard to rule out osteomyelitis.