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EliA Assays for Rheumatoid Arthritis (RA)

1 in 5 of those diagnosed with rheumatoid arthritis are incorrectly diagnosed.1

Use EliATM rheumatoid arthritis assays in your laboratory and help improve the diagnostic confidence of RA diagnoses.

What assays are a part of the are the EliA rheumatoid arthritis portfolio?

The EliA™ rheumatoid arthritis portfolio contains assays that detect ACPA (anti-citrullinated peptide antibodies) using CCP2 (2nd generation anti-cyclic citrullinated peptide) antigens as well as isotype-specific assays for rheumatoid factors (RF) IgM and IgA, all of which are recommended for a well-informed patient diagnosis.2-6

Three important RA assays to add in your laboratory

EliA CCP assay
In addition to testing for a highly specific RA marker, anti-CCP antibodies may be of prognostic value with respect to the development of radiographic joint damage. 3-7

IgM icon@3x
IgM icon@3x

EliA RF IgM assay

The EliA RF IgM assay tests for one of the most largely established biomarkers and rheumatoid factor isotypes found in RA patients. Paired with RF IgA, RF IgM can help clinicians diagnose RA with high confidence.5, 8, 12

EliA RF IgA assay

The EliA RF IgA assay tests for a marker which indicates severe disease outcomes and poor clinical responses to some drugs, such as TNF-α inhibitors, providing vital information to clinicians for disease management.9-11

Why use EliA CCP assay to aid in diagnosing rheumatoid arthritis?

Testing with the gold-standard antigen

The EliA CCP assay is highly specific, fully automated, and comprised of second generation CCP (CCP2), which is considered the gold standard antigen for ACPA testing.3

Why use EliA RF IgM and RF IgA assays to aid in diagnosing rheumatoid arthritis?

Isotype-specific RF testing  

EliA RF IgM and EliA RF IgA assays are isotype-specific, which provides added value compared to total RF assays based on agglutination (e.g. nephelometric or turbidimetric RF assays).12-13

EliA RF IgM and EliA RF IgA assays are isotype-specific, which provides added value compared to total RF assays based on agglutination (e.g. nephelometric or turbidimetric RF assays).12-13

Testing with EliA CCP, EliA RF IgM, and EliA RF IgA assays in parallel allows you to identify patients with positivity to two or more analytes, significantly increasing the positive likelihood ratio (LR+) and the positive predictive value (PPV) of test results as well as diagnostic confidence.14-16

Because positivity to only one RF isotype is not often associated with rheumatoid arthritis and because both IgM and IgA isotypes can appear years before the onset of disease symptoms, combining EliA RF IgM and EliA RF IgA in laboratory analysis is vital in helping identify and quickly manage RA.7, 8, 17

Why combine EliA RF and EliA CCP assays for rheumatoid arthritis?

Provide valuable information to clinicians

Less than 5% of non-RA patients are positive for both RF IgM and IgA, meaning double positivity is a strong indication of rheumatoid arthritis.12

Those positive for both anti-CCP and RF IgM and/or RF IgA are at a high risk for frequent and larger bone erosions as well as enhanced bone marrow edema.8

View EliA assays for rheumatoid arthritis in our product catalog

EliA rheumatoid arthritis laboratory testing algorithm

Applying a standardized testing profile with EliA assays for RA allow for convenient and efficient testing for primary care and specialists alike.

EliA CCP + EliA RF IgM + EliA RF IgA All EliA single tests negative EliA RF IgM positive or EliA RF IgA positive and EliA CCP negative EliA RF IgM positive and EliA RF IgA positive and EliA CCP negative EliA CCP positive and EliA RF IgA and/or EliA RF IgM positive or negative EliA CCP IgA and EliA RF IgG negative EliA CCP IgA and/or EliA RF IgG positive EliA CCP IgA + EliA RF IgG* RA unlikely** RA possible RA likely RA very likely * in case of clinical suspicion ** consider possible seronegativity Note: this test algorithm is presenting only some of the diagnostic approaches possible. Additional clinical and diagnostic tests are needed for a final diagnosis. Selected relevant guidelines and references for this test algorithm: “2010 ACR/EULAR classification criteria for rheumatoid arthritis”, Aletaha et al. 2010 2 “Relationship between rheumatoid factor isotypes and IgG anti-cyclic citrullinated peptide antibodies”, Jaskowski et al. 2010 14 “Determination of Autoantibody Isotypes Increases the Sensitivity of Serodiagnostics in Rheumatoid Arthritis”, Sieghart et al. 2018 15










For additional information on EliA RA testing, autoimmune diseases, and/or educational tools and resources, contact our experts.


Whether you’re a healthcare provider or laboratorian, Thermo Fisher Scientific offers valuable resources geared to your specific needs.


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  1. Santos-Moreno P, Villarreal-Peralta L, Gomez-Mora D, Castillo E, Malpica A, Castro C, et al. Osteoarthritis is the Most Frequent Cause of Rheumathoid Arthritis Misdiagnosis in a Rheumatology Center. Osteoarthritis and Cartilage. 2017;25:S219.
  2. Aletaha D, Neogi T, et al. 2010 Rheumatoid arthritis classification criteria: an American College of Rheumatology/European League Against Rheumatism collaborative initiative. Arthritis Rheum. 2010 Sep;62(9):2569-81. doi: 10.1002/art.27584. PMID: 20872595.
  3. van Venrooij, Walther J et al. “Anti-CCP antibodies: the past, the present and the future.” Nature reviews. Rheumatology vol. 7,7 391-8. 7 Jun. 2011, doi:10.1038/nrrheum.2011.76
  4. de Brito Rocha, S., Baldo, D.C. & Andrade, L.E.C. Clinical and pathophysiologic relevance of autoantibodies in rheumatoid arthritis. Adv Rheumatol 59, 2 (2019).
  5. Bizzaro, Nicola. “Antibodies to citrullinated peptides: a significant step forward in the early diagnosis of rheumatoid arthritis.” Clinical chemistry and laboratory medicine vol. 45,2 (2007): 150-7. doi:10.1515/CCLM.2007.027
  6. Littlejohn, Emily A, and Seetha U Monrad. “Early Diagnosis and Treatment of Rheumatoid Arthritis.” Primary care vol. 45,2 (2018): 237-255. doi:10.1016/j.pop.2018.02.010
  7. Rantapää-Dahlqvist, Solbritt et al. “Antibodies against cyclic citrullinated peptide and IgA rheumatoid factor predict the development of rheumatoid arthritis.” Arthritis and rheumatism vol. 48,10 (2003): 2741-9. doi:10.1002/art.11223
  8. Falkenburg, Willem J J, and Dirkjan van Schaardenburg. “Evolution of autoantibody responses in individuals at risk of rheumatoid arthritis.” Best practice & research. Clinical rheumatology vol. 31,1 (2017): 42-52. doi:10.1016/j.berh.2017.07.005
  9. Bobbio-Pallavicini, Francesca et al. “High IgA rheumatoid factor levels are associated with poor clinical response to tumour necrosis factor alpha inhibitors in rheumatoid arthritis.” Annals of the rheumatic diseases vol. 66,3 (2007): 302-7. doi:10.1136/ard.2006.060608
  10. Jónsson, T et al. “Raised IgA rheumatoid factor (RF) but not IgM RF or IgG RF is associated with extra-articular manifestations in rheumatoid arthritis.” Scandinavian journal of rheumatology vol. 24,6 (1995): 372-5. doi:10.3109/03009749509095183
  11. Houssien, D A et al. “Rheumatoid factor isotypes, disease activity and the outcome of rheumatoid arthritis: comparative effects of different antigens.” Scandinavian journal of rheumatology vol. 27,1 (1998): 46-53. doi:10.1080/030097498441173
  12. Jónsson, T et al. “Combined elevation of IgM and IgA rheumatoid factor has high diagnostic specificity for rheumatoid arthritis.” Rheumatology international vol. 18,3 (1998): 119-22. doi:10.1007/s002960050069
  13. Bas, S et al. “Comparative study of different enzyme immunoassays for measurement of IgM and IgA rheumatoid factors.” Annals of the rheumatic diseases vol. 61,6 (2002): 505-10. doi:10.1136/ard.61.6.505
  14. Jaskowski, Troy D et al. “Relationship between rheumatoid factor isotypes and IgG anti-cyclic citrullinated peptide antibodies.” The Journal of rheumatology vol. 37,8 (2010): 1582-8. doi:10.3899/jrheum.091236
  15. Sieghart, Daniela et al. “Determination of Autoantibody Isotypes Increases the Sensitivity of Serodiagnostics in Rheumatoid Arthritis.” Frontiers in immunology vol. 9 876. 24 Apr. 2018, doi:10.3389/fimmu.2018.00876
  16. Internal Study. Data on File
  17. Jónsson, T et al. “Elevation of only one rheumatoid factor isotype is not associated with increased prevalence of rheumatoid arthritis--a population based study.” Scandinavian journal of rheumatology vol. 29,3 (2000): 190-1. doi:10.1080/030097400750002094