Evaluation of synovial calprotectin by using a lateral flow stool test for the diagnosis of prosthetic joint infections

The analysis of synovial fluid is a crucial step in the diagnostic process of prosthetic joint infections (PJI) and several studies illustrated the efficacy of synovial calprotectin in supporting the diagnosis of PJI. In this study, synovial calprotectin was analyzed by a commercial stool test to explore whether the detected levels might predict PJIs. The synovial fluids of 55 were analyzed. Calprotectin levels were compared to other synovial biomarkers of PJI. Of the 55 synovial fluids, 13 patients were diagnosed with PJI and 42 with an aseptic failure of the implant. The specificity, sensitivity, and AUC of calprotectin resulted 0.90, 0.85, and 0.86 (95%CI: 0.72-0.99), respectively with a set threshold of 226.5 µg/g. The values of calprotectin had a moderate and statistically relevant correlation with the synovial leucocyte counts (rs = 0.54, p = 0.0003) and percentage of synovial neutrophils (rs = 0.68, p = 0.0000). From this analysis, it can be concluded that synovial calprotectin is a valuable biomarker that correlates with other established indicator of local infection, and the use of a commercial lateral flow stool test could be a cost-effective strategy delivering rapid and reliable results and supporting the diagnostic process of PJI.滑液分析是人工关节感染（prosthetic joint infections, PJI）诊断流程中的关键步骤，多项研究已证实滑液钙卫蛋白（synovial calprotectin）在辅助PJI诊断中的应用价值。本研究采用商用粪便检测试剂盒对滑液钙卫蛋白进行检测，以探究其检测水平能否预测PJI的发生。本研究共纳入55份滑液样本开展分析，并将钙卫蛋白水平与其他PJI相关滑液生物标志物进行对比。在55份滑液样本中，13例患者被确诊为PJI，42例为假体无菌性松动。当阈值设定为226.5 μg/g时，钙卫蛋白的特异性、灵敏度及曲线下面积（AUC）分别为0.90、0.85和0.86（95%置信区间：0.72-0.99）。钙卫蛋白水平与滑液白细胞计数（rs=0.54, p=0.0003）及滑液中性粒细胞百分比（rs=0.68, p=0.0000）均呈中等强度且具有统计学意义的相关性。综上，滑液钙卫蛋白是一种极具临床价值的生物标志物，与其他已确立的局部感染指示指标存在显著关联；采用商用侧向流粪便检测试剂盒可作为一种成本效益优异的策略，能够快速且可靠地获取检测结果，辅助PJI的诊断流程。