Preliminary evaluation of a rapid lateral flow calprotectin test for the diagnosis of prosthetic joint infection

Alexander J Trotter; Rachael Dean; Celia E Whitehouse; Jarle Mikalsen; Claire Hill; Roxanne Brunton-Sim; Gemma L Kay; Majeed Shakokani; Alexander Z E Durst; John Wain; Iain McNamara; Justin O'Grady

doi:10.1302/2046-3758.95.BJR-2019-0213.R1

Preliminary evaluation of a rapid lateral flow calprotectin test for the diagnosis of prosthetic joint infection

Bone Joint Res. 2020 Jun 8;9(5):202-210. doi: 10.1302/2046-3758.95.BJR-2019-0213.R1. eCollection 2020 May.

Authors

Affiliations

¹ University of East Anglia, Norwich, UK, Quadram Institute Bioscience, Norwich Research Park, Norwich, UK.
² Norfolk and Norwich University Hospitals Foundation Trust, Norwich, UK.
³ Lyfstone AS, Tromsø, Norway.
⁴ Quadram Institute Bioscience, Norwich Research Park, Norwich, UK, Norfolk and Norwich University Hospitals Foundation Trust, Norwich, UK.
⁵ Quadram Institute Bioscience, Norwich Research Park, Norwich, UK.
⁶ West Suffolk Hospital, Bury St Edmunds, UK.
⁷ University of East Anglia, Norwich, UK, Norfolk and Norwich University Hospitals Foundation Trust, Norwich, UK.

PMID: 32566141
PMCID: PMC7284294
DOI: 10.1302/2046-3758.95.BJR-2019-0213.R1

Abstract

Aims: This pilot study tested the performance of a rapid assay for diagnosing prosthetic joint infection (PJI), which measures synovial fluid calprotectin from total hip and knee revision patients.

Methods: A convenience series of 69 synovial fluid samples from revision patients at the Norfolk and Norwich University Hospital were collected intraoperatively (52 hips, 17 knees) and frozen. Synovial fluid calprotectin was measured retrospectively using a new commercially available lateral flow assay for PJI diagnosis (Lyfstone AS) and compared to International Consensus Meeting (ICM) 2018 criteria and clinical case review (ICM-CR) gold standards.

Results: According to ICM, 24 patients were defined as PJI positive and the remaining 45 were negative. The overall accuracy of the lateral flow test compared to ICM was 75.36% (52/69, 95% CI 63.51% to 84.95%), sensitivity and specificity were 75.00% (18/24, 95% CI 53.29% to 90.23%) and 75.56% (34/45, 95% CI 60.46% to 87.12%), respectively, positive predictive value (PPV) was 62.07% (18/29, 95% CI 48.23% to 74.19%) and negative predictive value (NPV) was 85.00% (34/40, 95% CI 73.54% to 92.04%), and area under the receiver operating characteristic (ROC) curve (AUC) was 0.78 (95% CI 0.66 to 0.87). Patient data from discordant cases were reviewed by the clinical team to develop the ICM-CR gold standard. The lateral flow test performance improved significantly when compared to ICM-CR, with accuracy increasing to 82.61% (57/69, 95% CI 71.59% to 90.68%), sensitivity increasing to 94.74% (18/19, 95% CI 73.97% to 99.87%), NPV increasing to 97.50% (39/40, 95% CI 85.20% to 99.62%), and AUC increasing to 0.91 (95% CI 0.81 to 0.96). Test performance was better in knees (100.00% accurate (17/17, 95% CI 80.49% to 100.00%)) compared to hips (76.92% accurate (40/52, 95% CI 63.16% to 87.47%)).

Conclusion: This study demonstrates that the calprotectin lateral flow assay could be an effective diagnostic test for PJI, however additional prospective studies testing fresh samples are required.Cite this article: Bone Joint Res. 2020;9(5):202-210.

Keywords: Calprotectin; Prosthetic joint infection; Rapid diagnostics; Synovial fluid.