JBJI Journal of Bone and Joint Infection JBJI J. Bone Joint Infect. 2206-3552 Ivyspring Göttingen, Germany 10.7150/jbji.26401 Qualitative Alpha-defensin Versus The Main Available Tests For The Diagnosis Of Periprosthetic Joint Infection: Best Predictor Test? Riccio Giovanni 1 Cavagnaro Luca 2 Akkouche Wassim 3 Carrega Giuliana 1 Felli Lamberto 2 Burastero Giorgio 4 Centro MIOS, S.C. Malattie Infettive, ASL 2 Savonese Ospedale di Pietra Ligure-Albenga Clinica Ortopedica - Ospedale Policlinico San Martino, Genova, Italy Patologia Clinica e Microbiologia, ASL 2 Savonese, Liguria Centro MIOS, S.C. Ortopedia 2, ASL 2 Savonese Ospedale di Pietra Ligure-Albenga 27 07 2018 3 3 156 164 Copyright: © 2018 Giovanni Riccio et al. 2018 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://jbji.copernicus.org/articles/3/156/2018/jbji-3-156-2018.html The full text article is available as a PDF file from https://jbji.copernicus.org/articles/3/156/2018/jbji-3-156-2018.pdf

<p class="p p-first" id="__p2"><strong>Introduction:</strong> Biomarkers such as α-defensin demonstrated to be a potentially useful option in periprosthetic joint infection (PJI) diagnosis. Recently, a new point-of-care test for α-defensin level detection in synovial fluid has been commercialized in Europe. The aim of this study is to compare the α-defensin test (Synovasure<sup>TM</sup>) diagnostic ability with the main available clinical tests for periprosthetic joint infection diagnosis in a practical clinical setting of a Bone Infection Unit.</p><p id="__p3"><strong>Methods:</strong> Between 2015 and 2017, 146 patients with suspected chronic PJI were screened with Synovasure<sup>TM</sup>. Seventy-three of these met the Musculoskeletal Infection Society (MSIS) criteria and were included in the analysis. According to MSIS criteria, 40 patients (54.7%) were classified as infected and 33 (45.3%) as not infected. The results obtained with Synovasure<sup>TM</sup> were recorded and compared with standard diagnostic methods for PJI diagnosis.</p><p id="__p4"><strong>Results:</strong> Synovasure<sup>TM</sup> showed a sensitivity of 85.0 % (95% CI 70.2 to 94.3) and a specificity of 96.9 % (95% CI 83.8 to 99.9) for PJI detection. The positive likelihood ratio of Synovasure<sup>TM</sup> was 27.2 (95% CI 3.9 to 188.1) and the negative likelihood ratio was 0.2 (95% CI 0.1 to 0.3). The diagnostic odds ratio was 181.3 (95% CI 20.7 to 1590.4). Synovasure<sup>TM</sup> demonstrated a statistical significant difference when compared to Erythrocyte Sedimentation Rate (ESR) and C-reactive Protein (CRP) specificity (at least one positive test) and preoperative culture sensitivity (1 positive culture).</p><p class="p p-last" id="__p5"><strong>Conclusion:</strong> Our findings show that Synovasure<sup>TM</sup> sensitivity is lower than quantitative α-D test, but when compared to the main available tests shows a good specificity and the highest DOR. On the SF it is the easier test to do, due to the fact that it needs a minimal amount of SF and it is not limited by blood contamination or antibiotic use. Whereas there is no single standalone test, Synovasure<sup>TM</sup> should be considered a reliable additional test for periprosthetic joint infection diagnosis in everyday clinical practice.</p>

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