J Bone Jt Infect 2018; 3(3):156-164. doi:10.7150/jbji.26401

Research Paper

Qualitative Alpha-defensin Versus The Main Available Tests For The Diagnosis Of Periprosthetic Joint Infection: Best Predictor Test?

Giovanni Riccio1, Luca Cavagnaro2, Wassim Akkouche3, Giuliana Carrega1, Lamberto Felli2, Giorgio Burastero4✉

1. Centro MIOS, S.C. Malattie Infettive, ASL 2 Savonese Ospedale di Pietra Ligure-Albenga
2. Clinica Ortopedica - Ospedale Policlinico San Martino, Genova, Italy
3. Patologia Clinica e Microbiologia, ASL 2 Savonese, Liguria
4. Centro MIOS, S.C. Ortopedia 2, ASL 2 Savonese Ospedale di Pietra Ligure-Albenga

Abstract

Introduction: 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 (SynovasureTM) diagnostic ability with the main available clinical tests for periprosthetic joint infection diagnosis in a practical clinical setting of a Bone Infection Unit.

Methods: Between 2015 and 2017, 146 patients with suspected chronic PJI were screened with SynovasureTM. 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 SynovasureTM were recorded and compared with standard diagnostic methods for PJI diagnosis.

Results: SynovasureTM 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 SynovasureTM 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). SynovasureTM 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).

Conclusion: Our findings show that SynovasureTM 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, SynovasureTM should be considered a reliable additional test for periprosthetic joint infection diagnosis in everyday clinical practice.

Keywords: Alpha-defensin, Synovasure, Periprosthetic joint infection, Synovial fluid

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How to cite this article:
Riccio G, Cavagnaro L, Akkouche W, Carrega G, Felli L, Burastero G. Qualitative Alpha-defensin Versus The Main Available Tests For The Diagnosis Of Periprosthetic Joint Infection: Best Predictor Test?. J Bone Jt Infect 2018; 3(3):156-164. doi:10.7150/jbji.26401. Available from http://www.jbji.net/v03p0156.htm