The Bone Infection Unit, Nuffield Orthopaedic Centre, Oxford University Hospitals Foundation NHS Trust, Oxford, UK.
Medical University of Vienna, Department of Orthopaedics and Trauma Surgery, Vienna, Austria.
Bone Joint J. 2020 Jul;102-B(7):904-911. doi: 10.1302/0301-620X.102B7.BJJ-2019-1739.R1.
The aim of this study was to evaluate the diagnostic value of preoperative serum CRP, white blood cell count (WBC), percentage of neutrophils (%N), and neutrophil to lymphocyte ratio (NLR) when using the fracture-related infection (FRI) consensus definition.
A cohort of 106 patients having surgery for suspected septic nonunion after failed fracture fixation were studied. Blood samples were collected preoperatively, and the concentration of serum CRP, WBC, and differential cell count were analyzed. The areas under the curve (AUCs) of diagnostic tests were compared using the z-test. Regression trees were constructed and internally cross-validated to derive a simple diagnostic decision tree.
Using the FRI consensus definition, 46 patients (43%) were identified as infected. Sensitivity, specificity, and AUC of CRP were 67% (95% confidence interval (CI) 52% to 80%), 61% (95% CI 47% to 74%), and 0.64 (95% CI 0.54 to 0.74); of WBC count were 17% (95% CI 9% to 31%), 95% (95% CI 86% to 99%), and 0.57 (95% CI 0.50 to 0.62); of %N 13% (95% CI 6% to 26%), 87% (95% CI 76% to 93%), and 0.50 (95% CI 0.43 to 0.56); and of NLR 28% (95% CI 17% to 43%), 80% (95% CI 68% to 88%), and 0.54 (95% CI 0.46 to 0.63), respectively. A better performance of serum CRP was shown in comparison to the leucocyte count (p = 0.006), %N (p < 0.001), and NLR (p = 0.001). A statistically lower serum CRP level was shown in patients with an infection caused by a low virulence microorganism in comparison to high virulence bacteria (p = 0.008). We found that a simple decision tree approach using only low serum neutrophils (< 3.615 × 10/l) and low CRP (< 2.45 mg/l) may allow better identification of aseptic cases.
The evaluated serum inflammatory markers showed limited diagnostic value in the preoperative diagnosis of FRI when using the uniform FRI Consensus Definition. Therefore, they should remain as suggestive criteria in diagnosing FRI. Although CRP showed a higher performance in comparison to the other serum markers, it is insufficiently accurate to diagnose a septic nonunion, especially when caused by low virulence microorganisms. Cite this article: 2020;102-B(7):904-911.
本研究旨在评估术前血清 C 反应蛋白（CRP）、白细胞计数（WBC）、中性粒细胞百分比（%N）和中性粒细胞与淋巴细胞比值（NLR）在使用骨折相关感染（FRI）共识定义时的诊断价值。
对 106 例因骨折固定失败后出现疑似感染性非愈合而接受手术的患者进行了研究。采集术前血样，分析血清 CRP、WBC 和细胞分类计数的浓度。使用 z 检验比较诊断试验的曲线下面积（AUC）。构建回归树并进行内部交叉验证，以得出简单的诊断决策树。
使用 FRI 共识定义，46 例（43%）患者被确定为感染。CRP 的灵敏度、特异度和 AUC 分别为 67%（95%CI 52%至 80%）、61%（95%CI 47%至 74%）和 0.64（95%CI 0.54 至 0.74）；WBC 计数为 17%（95%CI 9%至 31%）、95%（95%CI 86%至 99%）和 0.57（95%CI 0.50 至 0.62）；%N 为 13%（95%CI 6%至 26%）、87%（95%CI 76%至 93%）和 0.50（95%CI 0.43 至 0.56）；NLR 为 28%（95%CI 17%至 43%）、80%（95%CI 68%至 88%）和 0.54（95%CI 0.46 至 0.63）。与白细胞计数（p = 0.006）、%N（p < 0.001）和 NLR（p = 0.001）相比，CRP 显示出更好的性能。与高毒力细菌相比，低毒力微生物引起的感染患者血清 CRP 水平较低（p = 0.008）。我们发现，使用仅低血清中性粒细胞（<3.615×10/l）和低 CRP（<2.45mg/l）的简单决策树方法可能可以更好地识别无菌病例。
在使用统一的 FRI 共识定义时，评估的血清炎症标志物在 FRI 的术前诊断中显示出有限的诊断价值。因此，它们应作为诊断 FRI 的提示性标准。尽管 CRP 与其他血清标志物相比表现出更高的性能，但它不足以准确诊断感染性非愈合，尤其是由低毒力微生物引起的感染性非愈合。
