Diagnostic Value of Erythrocyte Sedimentation Rate and CReactive Protein in detecting Diabetic Foot Osteomyelitis;a Cross-sectional Study

Osteomyelitis is one of the complications of diabetic foot infection. The present study aimedto evaluate the diagnostic value of erythrocyte sedimentation rate (ESR) and C reactive protein (CRP) in detec-tion of osteomyelitis in patients with diabetic foot.

In this cross-sectional study, serum levels of ESRand CRP were measured for patients with diabetic foot referring to emergency department or endocrinologyclinic and the screening performance characteristics of these markers in detection of osteomyelitis were calcu-lated. The diagnosis of osteomyelitis was based on clinical examination and positive probe-to-bone test, whichwas confirmed by plain x-rays or MRI.

142 diabetic patients with an average age of 61.2±11.8 yearswere evaluated (66.2% male). The area under the ROC curve of ESR in detection of osteomyelitis in diabeticfoot cases was 0.70 (95% CI: 0.62-0.79). The best ESR cut-off point in this regard was 49 mm/hour. Sensitiv-ity, specificity, positive and negative predictive values, and positive and negative likelihood ratios of ESR in 49mm/Hour cut-point were 74.6% (95% CI: 62.9-83.9), 57.7% (95% CI: 45.5-69.2), 63.9% (95% CI: 52.5-73.9), 69.5%(95% CI: 56.0-80.0), 1.8 (95% CI: 1.3-2.4) and 0.4 (95% CI: 0.3-0.7), respectively. The area under the ROC curveof CRP in detection of osteomyelitis was 0.67 (95% CI: 0.58-0.76). The best cut-off point for CRP in this regardwas 35 mg/liter with sensitivity, specificity, positive and negative predictive values, and positive and negativelikelihood ratios of 76% (95% CI: 64.2-85), 54.9% (95% CI: 42.7-66.6), 62.8% (95% CI: 51.6-72.8), 69.6% (95% CI:51.7-80.8), 1.7 (95% CI, 1.3-2.2), and 0.4 (95% CI: 0.3-0.7), respectively.

Based on the findings ofROC curve analysis, ESR and CRP had fair and poor accuracy, respectively, in detecting the diabetic foot caseswith osteomyelitis.