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Analytical validation of a new point-of-care assay for serum amyloid A in horses.
Abstract: Serum amyloid A (SAA) is a major acute phase protein in horses. A new point-of-care (POC) test for SAA (Stablelab) is available, but studies evaluating its analytical accuracy are lacking. Objective: To evaluate the analytical performance of the SAA POC test by 1) determining linearity and precision, 2) comparing results in whole blood with those in serum or plasma, and 3) comparing POC results with those obtained using a previously validated turbidimetric immunoassay (TIA). Methods: Assay validation. Methods: Analytical validation of the POC test was done in accordance with American Society of Veterinary Clinical Pathology guidelines using residual equine serum/plasma and whole blood samples from the Clinical Pathology Laboratory at the University of California-Davis. A TIA was used as the reference method. We also evaluated the effect of haematocrit (HCT). Results: The POC test was linear for SAA concentrations of up to at least 1000 μg/mL (r = 0.991). Intra-assay CVs were 13, 18 and 15% at high (782 μg/mL), intermediate (116 μg/mL) and low (64 μg/mL) concentrations. Inter-assay (inter-batch) CVs were 45, 14 and 15% at high (1372 μg/mL), intermediate (140 μg/mL) and low (56 μg/mL) concentrations. SAA results in whole blood were significantly lower than those in serum/plasma (P = 0.0002), but were positively correlated (r = 0.908) and not affected by HCT (P = 0.261); proportional negative bias was observed in samples with SAA>500 μg/mL. The difference between methods exceeded the 95% confidence interval of the combined imprecision of both methods (15%). Conclusions: Analytical validation could not be performed in whole blood, the sample most likely to be used stall side. Conclusions: The POC test has acceptable accuracy and precision in equine serum/plasma with SAA concentrations of up to at least 1000 μg/mL. Low inter-batch precision at high concentrations may affect serial measurements, and the use of the same test batch and sample type (serum/plasma or whole blood) is recommended. Comparison of results between the POC test and the TIA is not recommended.
© 2018 EVJ Ltd.
Publication Date: 2018-02-19 PubMed ID: 29344980DOI: 10.1111/evj.12807Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
Summary
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The research focuses on the evaluation of a new point-of-care (POC) test for Serum Amyloid A (SAA) in horses. The study finds that the test has a reasonable level of accuracy and precision, although some issues were noted with variations between batches and results in whole blood.
Objectives and Methods
The aim of the research was to evaluate a new point-of-care (POC) test for Serum Amyloid A (SAA), an important protein that signifies immediate-phase response in horses. The study accomplished this by:
- Determining the linearity and precision of the POC test
- Comparing results obtained from whole blood with those from serum or plasma
- Comparing POC results with those obtained using a previously validated test, known as a turbidimetric immunoassay (TIA)
The analytical validation of the POC test was conducted in accordance with the American Society of Veterinary Clinical Pathology’s guidelines.
Results
The point-of-care test showed linearity for SAA concentrations upto at least 1000 μg/mL. However, the inter-assay (inter-batch) Coefficients of Variation (CVs) were revealed to be quite high at high concentrations.
It was also discovered that SAA results when using whole blood were notably lower than those obtained using serum/plasma. However, despite this, the two results still showed a positive correlation and didn’t appear to be affected by haematocrit.
The study also notes a significant proportional negative bias in samples containing SAA concentrations over 500 μg/mL and warns against comparing results between the POC test and the TIA, as their methods varied significantly.
Conclusions
The study concludes that, while the POC test displayed acceptable accuracy and precision in equine serum or plasma for SAA concentrations up to at least 1000 μg/mL, the analytical validation couldn’t be performed in whole blood. This is significant because whole blood is usually the sample type used for on-field tests. It suggests using the same batch and sample type to reduce variability. The study also highlights that comparing results from the POC test and the traditional TIA should be avoided.
Cite This Article
APA
Schwartz D, Pusterla N, Jacobsen S, Christopher MM.
(2018).
Analytical validation of a new point-of-care assay for serum amyloid A in horses.
Equine Vet J, 50(5), 678-683.
https://doi.org/10.1111/evj.12807 Publication
Researcher Affiliations
- Department of Pathology, Microbiology and Immunology, University of California, Davis, California, USA.
- Department of Medicine and Epidemiology, University of California, Davis, California, USA.
- Department of Veterinary Clinical Sciences, University of Copenhagen, Taastrup, Denmark.
- Department of Pathology, Microbiology and Immunology, University of California, Davis, California, USA.
MeSH Terms
- Animals
- Horses / blood
- Immunoassay / instrumentation
- Immunoassay / methods
- Immunoassay / veterinary
- Point-of-Care Systems
- Reproducibility of Results
- Serologic Tests / instrumentation
- Serologic Tests / methods
- Serologic Tests / veterinary
- Serum Amyloid A Protein / chemistry
- Serum Amyloid A Protein / metabolism
Citations
This article has been cited 14 times.- Hepworth-Warren KL, Estell K, Cowles B, Amodie D, Crisman M. Utility of serum amyloid A in monitoring clinical response to antimicrobial treatment in horses with bacterial pneumonia. J Vet Intern Med 2023 Sep-Oct;37(5):1917-1922.
- Ferlini Agne G, May BE, Lovett A, Simon O, Steel C, Santos L, Guedes do Carmo L, Barbosa B, Werner LC, Daros RR, Somogyi AA, Sykes B, Franklin S. Horse Grimace Scale Does Not Detect Pain in Horses with Equine Gastric Ulcer Syndrome. Animals (Basel) 2023 May 12;13(10).
- Palmisano M, Javsicas L, McNaughten J, Gamsjäger L, Renaud DL, Gomez DE. Effect of plasma transfusion on serum amyloid A concentration in healthy neonatal foals and foals with failure of transfer of passive immunity. J Vet Intern Med 2023 Mar;37(2):697-702.
- Berryhill EH, Urbina NS, Marton S, Vernau W, Alonso FH. Validation and method comparison for a point-of-care lateral flow assay measuring equine whole blood insulin concentrations. J Vet Diagn Invest 2023 Mar;35(2):124-131.
- Taylor SD, Serpa PBS, Santos AP, Hart KA, Vaughn SA, Moore GE, Mukhopadhyay A, Page AE. Effects of intravenous administration of peripheral blood-derived mesenchymal stromal cells after infusion of lipopolysaccharide in horses. J Vet Intern Med 2022 Jul;36(4):1491-1501.
- Kiemle J, Hindenberg S, Bauer N, Roecken M. Comparison of a point-of-care serum amyloid A analyzer frequently used in equine practice with 2 turbidimetric immunoassays used in human and veterinary medicine. J Vet Diagn Invest 2022 Jan;34(1):42-53.
- Escribano D, Bustillo AO, Marín LP, Rabasco AN, Herrera PR, Cerón JJ, Tvarijonaviciute A. Analytical Validation of Two Point-of-Care Assays for Serum Amyloid A Measurements in Cats. Animals (Basel) 2021 Aug 27;11(9).
- Menzel A, Samouda H, Dohet F, Loap S, Ellulu MS, Bohn T. Common and Novel Markers for Measuring Inflammation and Oxidative Stress Ex Vivo in Research and Clinical Practice-Which to Use Regarding Disease Outcomes?. Antioxidants (Basel) 2021 Mar 9;10(3).
- Frydendal C, Nielsen KB, Berg LC, van Galen G, Adler DMT, Andreassen SM, Jacobsen S. Influence of clinical and experimental intra-articular inflammation on neutrophil gelatinase-associated lipocalin concentrations in horses. Vet Surg 2021 Apr;50(3):641-649.
- Long A, Nolen-Walston R. Equine Inflammatory Markers in the Twenty-First Century: A Focus on Serum Amyloid A. Vet Clin North Am Equine Pract 2020 Apr;36(1):147-160.
- Jacobsen S, Vinther AM, Kjelgaard-Hansen M, Nielsen LN. Validation of an equine serum amyloid A assay with an unusually broad working range. BMC Vet Res 2019 Dec 19;15(1):462.
- Odelros E, Kendall A, Hedberg-Alm Y, Pringle J. Idiopathic peritonitis in horses: a retrospective study of 130 cases in Sweden (2002-2017). Acta Vet Scand 2019 Apr 25;61(1):18.
- Souto PC, Santos MR, Orozco AMO, Bento LD, Ramirez-Lopez CJ, Girardi FM, Machado JCA, de Oliveira LL, da Fonseca LA. Enzyme-Linked Immunosorbent Assay (ELISA) Development for Equine Serum Amyloid A (SAA) Determination Using Recombinant Proteins. Methods Protoc 2025 Apr 7;8(2).
- Usimaki A, Ciamillo SA, Barot D, Linardi RL, Engiles JB, Ortved KF. Single injection of intra-articular autologous protein solution in horses with acute interleukin-1B-induced synovitis decreases joint pathology scores. Equine Vet J 2025 May;57(3):806-816.
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