H. K. Eriksson, J. Nordström, N. P. Hailer, S. Lazarinis, Department of Surgical Sciences/Orthopaedics, Uppsala University Hospital, Uppsala, Sweden K. Gabrysch, UCR | Uppsala Clinical Research Center, Uppsala, Sweden.
Clin Orthop Relat Res. 2018 May;476(5):1065-1072. doi: 10.1007/s11999.0000000000000244.
Measuring alpha-defensin concentrations in synovial fluid may help to diagnose periprosthetic joint infection (PJI). There are two commercially available methods for measuring alpha-defensin in synovial fluid: the enzyme-linked immunosorbent assay-based Synovasure® alpha-defensin immunoassay, which gives a numeric readout within 24 hours, and the Synovasure lateral flow test, which gives a binary readout within 20 minutes. There is no compilation of the existing literature to support the use of one of these two tests over the other.
QUESTIONS/PURPOSES: Does the immunoassay or the lateral flow test have better diagnostic value (sensitivity and specificity) in diagnosing PJI?
We followed PRISMA guidelines and identified all studies on alpha-defensin concentration in synovial fluid as a PJI diagnostic marker, indexed to April 14, 2017, in PubMed, JSTOR, Google Scholar, and OVID databases. The search retrieved 1578 records. All prospective and retrospective studies on alpha-defensin as a PJI marker (PJI classified according to the criteria of the Musculoskeletal Infection Society) after THA or TKA were included in the analysis. All studies used only one of the two commercially available test methods, but none of them was comparative. After excluding studies with overlapping patient populations, four studies investigating the alpha-defensin immunoassay and three investigating the lateral flow test remained. Alpha-defensin immunoassay studies included 482 joints and lateral flow test studies included 119. The quality of the trials was assessed according to the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. The heterogeneity among studies was evaluated by the I index, indicating that the heterogeneity of the included studies was low. Pooled sensitivity, specificity, positive and negative likelihood ratios, and receiver operating curves were calculated for each method and compared with each other.
The alpha-defensin immunoassay had superior overall diagnostic value compared with the lateral flow test (area under the curve, 0.98 versus 0.75) with higher sensitivity (96% [90%-98%] versus 71% [55%-83%], p < 0.001), but no difference in specificity with the numbers available (96% [93%-97%] versus 90% [81%-95%], p = 0.060).
Measurement of alpha-defensin in synovial fluid is a valuable complement to existing diagnostic criteria, and the immunoassay test detects PJI more accurately than the lateral flow test. The lateral flow test has lower sensitivity, making it difficult to rule out infection, but its relatively high specificity combined with the advantage of a quick response time can make it useful to rule in infection perioperatively.
Level III, diagnostic study.
测量滑液中的α-防御素浓度有助于诊断假体周围关节感染（PJI）。有两种商业上可用于测量滑液中α-防御素的方法：基于酶联免疫吸附测定的Synovasure®α-防御素免疫分析，可在 24 小时内提供数值读数，以及 Synovasure 侧流测试，可在 20 分钟内提供二进制读数。目前尚无文献综述支持这两种方法中的任何一种优于另一种。
问题/目的：免疫分析或侧流测试在诊断 PJI 方面具有更好的诊断价值（敏感性和特异性）？
我们遵循 PRISMA 指南，确定了截至 2017 年 4 月 14 日在 PubMed、JSTOR、Google Scholar 和 OVID 数据库中索引的所有关于滑液中α-防御素浓度作为 PJI 诊断标志物的研究。该检索共检索到 1578 条记录。所有前瞻性和回顾性研究均纳入了α-防御素作为 PJI 标志物（根据肌肉骨骼感染协会的标准分类为 PJI），并在 THA 或 TKA 后进行。所有研究均仅使用两种商业上可获得的测试方法中的一种，但均未进行比较。在排除具有重叠患者人群的研究后，有四项研究调查了α-防御素免疫分析，三项研究调查了侧流测试。α-防御素免疫分析研究纳入了 482 个关节，侧流测试研究纳入了 119 个关节。根据诊断准确性研究的质量评估（QUADAS-2）工具评估了试验的质量。通过 I 指数评估研究之间的异质性，表明纳入研究的异质性较低。为每种方法计算了合并敏感性、特异性、阳性和阴性似然比以及受试者工作特征曲线，并相互比较。
与侧流测试相比，α-防御素免疫分析具有更高的整体诊断价值（曲线下面积，0.98 对 0.75），且具有更高的敏感性（96%[90%-98%]对 71%[55%-83%]，p<0.001），但特异性无差异根据可用数量（96%[93%-97%]对 90%[81%-95%]，p=0.060）。
滑液中α-防御素的测量是现有诊断标准的有价值的补充，免疫分析检测比侧流测试更准确地检测 PJI。侧流测试的敏感性较低，难以排除感染，但它相对较高的特异性与快速响应时间的优势相结合，可以在围手术期有用地检测感染。
III 级，诊断研究。
