Synovial fluid α-defensin in the diagnosis of periprosthetic joint infection: the lateral flow test is an effective intraoperative detection method

Abstract

Background Synovial fluid α-defensin is a valuable biomarker for periprosthetic joint infection (PJI). Its diagnostic value for PJI has been widely evaluated recently, but results are inconsistent, especially for different test methods. The objective of this study was to evaluate the diagnostic value of laboratory-based immunoassay and lateral flow testing for the detection of α-defensin against hip and knee PJI. Methods We systematically searched MEDLINE and EMBASE for articles on the diagnostic accuracy of α-defensin for PJI published up to September 2018. The pooled sensitivity, specificity, area under the curve (AUC), positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were calculated for the evaluation of the diagnostic value of α-defensin for PJI. Results Nineteen studies were included. Eleven evaluated laboratory-based immunoassay, and 10 evaluated the lateral flow test results. The pooled sensitivity, specificity, AUC, PLR, NLR, and DOR of laboratory-based immunoassays were 0.96 (95% confidence interval [CI] 0.90–0.98), 0.97 (95% CI 0.95–0.99), 0.99 (95% CI 0.98–1.00), 35.0 (95% CI 18.5–66.2), 0.04 (95% CI 0.02–0.11), and 811 (95% CI 220–2990), respectively. The pooled sensitivity, specificity, AUC, PLR, NLR, and DOR of the lateral flow test were 0.86 (95% CI 0.81–0.91), 0.96 (95% CI 0.93–0.98), 0.95 (95% CI 0.93–0.97), 21.2 (95% CI 11.7–38.5), 0.14 (95% CI 0.10–0.21), and 148 (95% CI 64–343), respectively. Conclusions Laboratory-based immunoassay of α-defensin is highly accurate for the diagnosis of hip and knee PJI. The lateral flow test is less sensitive but still a useful intraoperative detection tool for PJI.

Diagnostic Accuracy of the Synovial Fluid α‐Defensin Lateral Flow Test in Periprosthetic Joint Infection: A Meta‐analysis

“…The diagnostic reliability and accuracy of α‐defensin in PJI has been widely evaluated during the past few years 12,24,27,36,39,42 , and some studies have confirmed that α‐defensin is highly accurate for diagnosing PJI 27,36,39,42,44 . While some indicate that the α‐defensin lateral flow test is less sensitive and may be used as a confirmatory test for PJI 23,39 . This systematic review and meta‐analysis of 17 studies indicated that the α‐defensin lateral flow test had a pooled sensitivity, specificity, and AUC of 0.83 (95% CI 0.77, 0.88), 0.95 (95% CI 0.93, 0.97), and 0.97 (95% CI 0.95, 0.98), respectively.…”

“…It induces rapid death of the microorganisms by promoting depolarization of the cell membrane via interacting with or binding to the negatively charged membranes 16,21,22 . Recent evidence shows that Alpha‐defensin might be an ideal biomarker for PJI 14,23 . Ahmad et al 14 .…”

“…proved that laboratory‐based α‐defensin ELISA test showed a higher ever reported accuracy in PJI diagnosis compared with Synovasure lateral flow test. In 2018, Han et al 23 . indicated that laboratory‐based α‐defensin ELISA test has a higher pooled sensitivity, specificity, and accuracy than the α‐defensin lateral flow test (sensitivity: 0.96 vs 0.86; specificity: 0.97 vs 0.96; accuracy: 0.99 vs 0.95, respectively).…”

“…However, some studies showed the higher accuracy of the α‐defensin lateral flow test in PJI diagnosis than the MSIS criteria including CRP and erythrocyte sedimentation rate (ESR), and polymorphonuclear lymphocytes 2,24 . Accordingly, α‐defensin protein has been recommended to be included in the diagnostic algorithm in the future 12,14,23 . Before that, the accuracy of the α‐defensin lateral flow test in PJI should be fully analyzed.…”

New developments and future challenges in prevention, diagnosis, and treatment of prosthetic joint infection

“…Produced primarily by PMN, α‐defensins are a set of related low molecular weight polypeptides (called antimicrobial peptides) that have antibacterial activity 14 . When used for the diagnosis of PJI in SF, it achieved sensitivity and specificity of over 90% in the hands of multiple investigators 14,69–74 . In addition, a recently introduced lateral flow immunoassay kit, Synovasure, is now recommended for rapid analysis (~20 minutes) in the surgical suite, though it was found to be slightly less sensitive 15,16,74 .…”