Biomarkers for Early Detection of Charcot Arthropathy: A Prospective Study on Type 2 Diabetes Patients with Severe Neuropathy

Background: Charcot arthropathy (CA) is a progressive noninfectious inflammatory disease that causes irreversible destruction to pedal architecture in diabetic neuropathy (DN) patients. The debilitating prognosis demands early detection to prevent the development and progression of this disorder. Dysregulated and persistent production of inflammatory cytokines is reported as the key element in initiating osteoclastogenesis in CA. The study analyzed the potential association of markers of inflammation and bone turnover of prediagnostic serum samples on CA. Methods: Seventy-one type 2 severe DN patients were selected based on inclusion-exclusion criteria. Serum samples of interleukin 6 (IL-6), osteoprotegerin (OPG), bone alkaline phosphatase (BALP), and C-reactive protein (CRP) were analyzed. These patients were followed for the development of symptoms of CA for 12 months. In the year of monitoring, 7 patients developed CA (group 1), whereas the remaining 64 patients did not develop CA (group 2). Results: The rate of development of CA in patients with severe DN was 9.8%. In this group, significantly increased median values of Hb A1c (group 2: 8.00 [7.00-9.00], group 1: 10.00 [9.25-11.50], P = .013); IL-6 (group 2: 1.21 [0.72-2.16], group 1: 11.08 [6.65-63.64], P = .008); and CRP (group 2: 1.25 [0.78-3.20], group 1: 3.31 [1.18-41.33], P = .041) were found. The receiver operating characteristic analysis showed that IL-6 was more strongly associated with the onset of CA (IL-6: area under the curve = 0.808; P = .008) than CRP. Cut-off values of ≥6.6 for IL-6 show potential to rule out CA in high-risk patients, with a positive predictive value of 26.1%, a negative predictive value of 97.9%, a sensitivity of 85.7%, and a specificity of 73.4%. Conclusion: In our study population, we found that an exacerbated inflammatory state, reflected by IL-6 values, generally occurred in DN patients before the clinical detection of CA. Level of Evidence: Level II, prospective comparative study.