Erythrocyte sedimentation rate and C-reactive protein to monitor treatment outcomes in diabetic foot osteomyelitis

Abstract

This study sought to evaluate the effectiveness of the inflammatory markers, erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP), in monitoring treatment of osteomyelitis in the diabetic foot. We screened 150 charts of patients admitted to our hospital with diabetic foot osteomyelitis (DFO), confirmed by positive results of bone culture and/or histopathology. We included patients who had an initial ESR/CRP within 72 hours of admission and two reported follow-up values. We dichotomised patients based on the outcomes wound healing, re-infection, recurrent ulceration, re-hospitalisation, additional surgery, re-amputation and death, all within 12 months, and analysed the trajectories of the markers over time. Our primary outcome, DFO remission, was defined as wound healing within 12 months of follow-up without re-infection. We included 122 subjects; 65 patients (53·3%) had a combination of positive culture and histopathology. Factors associated with DFO remission (n = 46) were a lower white blood count (WBC) at admission (P = 0·006) and a higher glomerular filtration rate (GFR, P = 0·049). Factors associated with healing were a lower WBC (P = 0·004), a higher GFR (P = 0·01), longer wound duration before admission (P = 0·01), location of the ulcer on the great toe (P = 0·01) and higher glycated haemoglobin (P = 0·03). Logistic regression analysis demonstrated no associations between DFO remission and other variables collected. Trajectories of the inflammatory markers showed an association between stagnating values of ESR and CRP and poor clinical outcomes. In this study population, the trajectories of both ESR and CRP during 12 months follow-up suggest a predictive role of both inflammatory markers when monitoring treatment of DFO.

Keywords: Biomarkers; C-reactive protein; Diabetic foot infection; Erythrocyte sedimentation rate; Osteomyelitis.

Figure 1

Trajectories of average erythrocyte sedimentation rate within the outcome groups DFO remission, healing, re‐infection, re‐amputation and re‐hospitalisation over 12 months of follow‐up. (A) Average ESR within outcome group DFO remission, (B) average ESR within outcome group healing, (C) average ESR within outcome group reinfection, (D) average ESR within outcome group re‐amputation and (E) average ESR within outcome group re‐hospitalization. DFO, diabetic foot osteomyelitis; ESR, erythrocyte sedimentation rate.

Figure 2

Tajectories of average C‐reactive protein (CRP) within the outcome groups diabetic foot osteomyelitis (DFO) remission, healing and re‐amputation over 12 months of follow‐up. (A) Average CRP within outcome group DFO remission, (B) average CRP within outcome group healing (C) average CRP within outcome group re‐amputation.