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Clinical and epidemiological research
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Diagnostic value of anti-MCV antibodies in differentiating early inflammatory arthritis
  1. L Damjanovska1,2,
  2. M M Thabet1,3,
  3. E W N Levarth1,
  4. G Stoeken-Rijsbergen1,
  5. E I van der Voort1,
  6. R E M Toes1,
  7. T W J Huizinga1,
  8. A H M van der Helm-van Mil1
  1. 1Department of Rheumatology, Leiden University Medical Centre, Leiden, The Netherlands
  2. 2Rheumatology Clinic Dr Dimitar Arsov, University Sts Cyril and Methodius, Skopje FYR, Macedonia
  3. 3Department of Internal Medicine, Assiut University Hospital, Assiut, Egypt
  1. Correspondence to Dr M M Thabet, Department of Rheumatology, Leiden University Medical Centre, PO Box 9600, 2300 RC Leiden, The Netherlands; m.thabet{at}lumc.nl

Abstract

Objectives To evaluates the diagnostic performance of the anti-CCP2, anti-CCP3 and anti-mutated citrullinated vimentin (anti-MCV) tests in differentiating rheumatoid arthritis (RA) from other forms of arthritis in a clinical setting of early arthritis.

Methods In 917 patients with recent-onset arthritis (566 RA, 351 other diseases) and in 99 healthy controls the anti-MCV, anti-CCP2 and anti- CCP3.1 tests were performed and the test characteristics compared.

Results Comparison of the tests for differentiating RA from other causes of arthritis showed a lower specificity for anti-MCV (82.9%) than for anti-CCP2 (93.4%) and anti-CCP3.1 (90.0%). Similarly, the positive likelihood ratio for anti-MCV was also lower (3.6, compared with 8.7, 5.8 for anti-CCP2 and anti-CCP3.1). The anti-MCV test had a higher sensitivity (62% vs 56.9% and 58.1%, respectively). In psoriatic arthritis, spondyloarthropathy and other arthritis anti-MCV antibodies had a prevalence of 15.2%, 13.9% and 19.4%.

Conclusion The diagnostic performance of the anti-MCV test in the differential diagnosis of early arthritis is lower than that of the anti-CCP tests.

https://doi.org/10.1136/ard.2009.108456

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    Introduction

    Autoantibody formation is characteristic for rheumatoid arthritis (RA). The best known autoantibody is rheumatoid factor, which, however, lacks specificity. More recently, several tests have been developed that detect anti-citrullinated protein antibodies (ACPA). These tests include the commercially available anti-CCP2 and anti-CCP3 assays as well as the anti-mutated citrullinated vimentin (anti-MCV) test. The first two assays use citrullinated peptide(s) for the detection of ACPA, whereas the later assay is based on an entire protein, citrullinated vimentin.1 2

    Several recent studies examined the test characteristics of the anti-MCV test and the anti-CCP21 3,–,9 and anti-CCP3 tests,3 7 showing conflicting results (online supplementary table). This might be partly due to a limited sample size.3,–,9 In addition, in the majority of these studies patients with RA were compared with healthy controls, which means that the results cannot be easily extrapolated to clinical practice where these tests are used to differentiate early RA from other forms of early inflammatory arthritis. Therefore this study aimed to evaluate the diagnostic performance of the anti-MCV test in the differentiation of RA from other forms of inflammatory arthritis in a large inception cohort of patients with early arthritis and to compare these test characteristics with those of the anti-CCP2 and anti-CCP3.1 tests.

    Patients and methods

    Patients

    A total of 917 patients with early arthritis who were part of the Leiden Early Arthritis Clinic (EAC) were studied. The Leiden EAC is an inception cohort that started in 1993 at the Department of Rheumatology, Leiden University Medical Centre, the Netherlands and includes patients with recent-onset arthritis (symptom duration <2 years).10 All patients with RA, psoriatic arthritis (PsA), spondyloarthropathy (SpA) and baseline serum available, as well as a random selection of patients with other forms of arthritis were evaluated. The 917 patients had the following diagnoses: 566 RA according to the 1987 revised American College of Rheumatology classification criteria for RA,11 99 PsA, 72 SpA, 38 patients reactive arthritis, 32 inflammatory osteoarthritis, 30 remitting seronegative symmetrical synovitis with pitting oedema, 21 connective tissue diseases, 26 sarcoidosis, 11 paramalignant arthritis, 6 gout and pseudo-gout, 6 Lyme disease, 2 juvenile idiopathic arthritis and 8 patients with other inflammatory arthritis. RA was diagnosed at baseline (75%) or within the first year of follow-up (25%). The other patients were diagnosed at baseline in 73% and within the first year in 27%. The diagnoses made by the treating doctor were checked by an independent rheumatologist using chart review and existing criteria. Ninety-nine anonymous blood donors who served as healthy controls were also studied.

    ACPA measurement

    From all patients and controls, stored baseline serum samples were used to perform the anti-MCV, anti-CCP2 and anti-CCP3.1 tests. Anti-MCV antibodies were measured by a commercially available anti-MCV ELISA (Orgentec Diagnostika, Mainz, Germany). The assay was performed according to the manufacturer's instructions and values >20 U/ml were considered positive. Anti-CCP2 antibodies were measured by Immunoscan CCPlus (Euro-Diagnostica, Arnhem, the Netherlands) and anti-CCP3.1 antibodies using Quanta Lite CCP 3.1 IgG/IgA (Inova, California, USA). The cut-off points were used as determined by manufacturers, 25 U/ml for CCP2 and 20 U/ml for CCP3.1.

    Statistical analysis

    Sensitivity and specificity with 95% CI as well as the positive and negative likelihood ratios (LR+, LR–) were calculated for each of the tests. Receiver operating characteristic curves were constructed by plotting sensitivity (true-positive rate) against 1–specificity (false-positive rate) and the areas under the curve (AUCs) were compared. For analysis SPSS version 16 (SPSS 16 Chicago, Illinois, USA) was used. In all tests, p values <0.05 were considered statistically significant.

    Results

    Of the 917 patients with early arthritis 566 patients had RA, 99 PsA, 72 SpA and 180 other forms of inflammatory arthritis. To evaluate the diagnostic performance of the tests in the differentiation of RA from other forms of arthritis, the patients with PsA, SpA and other diagnoses were grouped. Among the patients with RA 379 (67%) were female; the mean age was 56.9±15 years. In the group with all other patients with early arthritis the mean age was 45.9±16.8 years and 184 (52%) were female (both p values <0.001 vs RA).

    Anti-MCV antibodies were present in 351/566 (62%) patients with RA and in 60/351 (17.1%) of all other forms of inflammatory arthritis. Dividing this group into disease categories showed that anti-MCV antibodies were present in 13.9% of patients with SpA, 15.2% with PsA and 19.4% with other forms of arthritis. As depicted in figure 1 the prevalence of anti-CCP2 and anti-CCP3.1 antibody positivity in these conditions was significantly lower. Figure 2 shows the prevalence of autoantibodies in RA, PsA plus SpA and other forms of early inflammatory arthritis, given that they were positive in the anti-CCP2/3, respectively anti-MCV assay. This figure indicates that most anti-MCV-positive patients with RA (82%) are also positive in the anti-CCP assays. More importantly, the results depicted in figure 2 illustrate that only 40% of anti-MCV-positive patients with other inflammatory arthritides are anti-CCP positive. These results indicate that the anti-MCV assay is less specific for RA than the two anti-CCP assays.

    Figure 1
    Figure 1

    Prevalence of autoantibody positivity in early arthritis and in healthy controls. CCP, cyclic citrullinated peptide; MCV, anti-mutated citrullinated vimentin; PsA, psoriatic arthritis; RA, rheumatoid arthritis; SpA, spondyloarthropathy.

    Figure 2
    Figure 2

    Prevalence of anti-MCV and anti-CCP2/3 antibodies in different diagnoses. AB+, antibody positive; AB−, antibody negative; CCP+, patients tested positive for either anti-CCP2 and/or anti-CCP3; MCV+, patients tested positive for anti-MCV; CCP+ MCV+, patients tested positive for (either anti-CCP2 and/or anti-CCP3) and positive for anti-MCV. CCP, cyclic citrullinated peptide; MCV, anti-mutated citrullinated vimentin; PsA, psoriatic arthritis; RA, rheumatoid arthritis; SpA, spondyloarthropathy.

    Indeed, as shown in table 1, in differentiating RA from other forms of inflammatory arthritis, the anti-MCV test displayed a slightly higher sensitivity than anti-CCP2 and anti-CCP3.1 (62% vs 56.9% and 58.1%). Importantly, however, the specificity of anti-MCV was lower (82.9% vs 93.4% and 90% for anti-CCP2 and anti-CCP3.1). In addition the LR+ was clearly higher for anti-CCP2 (8.7) and anti-CCP3.1 (5.8) than for anti-MCV (3.6). The AUCs of anti-CCP3.1 and anti-CCP2 were greater than the AUC of anti-MCV.

    View this table:
    Table 1

    Diagnostic performance of anti-MCV, anti-CCP2 and anti-CCP3.1 in differentiating RA from other early arthritis and from healthy controls

    In the 99 healthy controls six subjects had anti-MCV antibodies (6.1%), compared with one person positive for anti-CCP2 and one person positive for anti-CCP3.1. The test characteristics in differentiating RA from healthy controls showed that the anti-MCV test had the highest sensitivity but the lowest specificity (93.9% compared with 99.0% for anti-CCP2 and anti-CCP3.1) (table 1). In addition, the LR+ was markedly higher for anti-CCP2 and anti-CCP3.1 than for anti-MCV (56.3, 57.5 and 10.2, respectively).

    Discussion

    This study evaluated the diagnostic performance of a novel commercially available anti-MCV ELISA test for the detection of anti-MCV antibodies in differentiating patients with RA from those with other forms of early inflammatory arthritis, taking advantage of a large inception cohort. Using the cut-off values as indicated by the manufacturer, the anti-MCV assay displayed a higher sensitivity but a lower specificity than with a second- and third-generation anti-CCP test. In addition, the LR+ was higher for anti-CCP2 and anti-CCP3.1 than for anti-MCV, suggesting that a positive anti-CCP2 or anti-CCP3.1 test indicates a greater probability for RA than a positive anti-MCV test. This finding is further supported by the observation of a high prevalence of anti-MCV antibodies in other forms of arthritis, reducing its discriminative ability in an early arthritis setting.

    An increased prevalence (6–10%) of anti-CCP2 antibodies has been reported previously in PsA.12,–,14 We observed a prevalence of anti-CCP2 of 6.1% in PsA and an approximately three times higher percentage of anti-MCV positivity. The antibodies detected by the anti-MCV test were relatively frequently present in PsA and also in SpA and other forms of inflammatory arthritis, suggesting that these antibodies are not highly specific for RA.

    The current observation of a higher sensitivity but a lower specificity in differentiating RA from other inflammatory arthritis is in line with a previous study comparing the test characteristics in 92 patients with RA and 150 patients with other forms of arthritis.8 The strengths of our study are the sample size (n=917) and the early arthritis setting, representing the situation in clinical practice where these autoantibody tests are used. Generally, the autoantibody tests are performed in patients with recent-onset arthritis in order to differentiate between different diagnoses.

    In conclusion, the diagnostic performance of the anti-MCV test in the differential diagnosis of early arthritis is lower than that of the anti-CCP tests. Anti-MCV antibodies are present in 13.9–19.4% of non-RA arthritis. It will be interesting to know whether the presence of the antibodies detected by the anti-MCV assay is related to arthritis only or whether they will be found in other inflammatory disorders as well.

    Acknowledgments

    Cypress Bioscience, Inc is acknowledged for providing anti-CCP3 and anti-MCV ELISAs.

    References

    1. ↵
      1. Bang H,
      2. Egerer K,
      3. Gauliard A,
      4. et al
      . Mutation and citrullination modifies vimentin to a novel autoantigen for rheumatoid arthritis. Arthritis Rheum 2007;56:2503–11.
      OpenUrlCrossRefPubMedWeb of Science
    2. ↵
      1. Vossenaar ER,
      2. Després N,
      3. Lapointe E,
      4. et al
      . Rheumatoid arthritis specific anti-Sa antibodies target citrullinated vimentin. Arthritis Res Ther 2004;6:R142–50.
    3. ↵
      1. Coenen D,
      2. Verschueren P,
      3. Westhovens R,
      4. et al
      . Technical and diagnostic performance of 6 assays for the measurement of citrullinated protein/peptide antibodies in the diagnosis of rheumatoid arthritis. Clin Chem 2007;53:498–504.
      OpenUrlAbstract/FREE Full Text
    4. ↵
      1. Soós L,
      2. Szekanecz Z,
      3. Szabó Z,
      4. et al
      . Clinical evaluation of anti-mutated citrullinated vimentin by ELISA in rheumatoid arthritis. J Rheumatol 2007;34:1658–63.
      OpenUrlAbstract/FREE Full Text
    5. ↵
      1. Mathsson L,
      2. Mullazehi M,
      3. Wick MC,
      4. et al
      . Antibodies against citrullinated vimentin in rheumatoid arthritis: higher sensitivity and extended prognostic value concerning future radiographic progression as compared with antibodies against cyclic citrullinated peptides. Arthritis Rheum 2008;58:36–45.
      OpenUrlCrossRefPubMedWeb of Science
    6. ↵
      1. Dejaco C,
      2. Klotz W,
      3. Larcher H,
      4. et al
      . Diagnostic value of antibodies against a modified citrullinated vimentin in rheumatoid arthritis. Arthritis Res Ther 2006;8:R119.
      OpenUrlCrossRefPubMed
    7. ↵
      1. Bizzaro N,
      2. Tonutti E,
      3. Tozzoli R,
      4. et al
      . Analytical and diagnostic characteristics of 11 2nd- and 3rd-generation immunoenzymatic methods for the detection of antibodies to citrullinated proteins. Clin Chem 2007;53:1527–33.
      OpenUrlAbstract/FREE Full Text
    8. ↵
      1. Poulsom H,
      2. Charles PJ
      . Antibodies to citrullinated vimentin are a specific and sensitive marker for the diagnosis of rheumatoid arthritis. Clin Rev Allergy Immunol 2008;34:4–10.
      OpenUrlCrossRefPubMedWeb of Science
    9. ↵
      1. Roland PN,
      2. Mignot SG,
      3. Bruns A,
      4. et al
      . Antibodies to mutated citrullinated vimentin for diagnosing rheumatoid arthritis in anti-CCP-negative patients and for monitoring infliximab therapy. Arthritis Res Ther 2008;10(6):R142.
      OpenUrlCrossRefPubMed
    10. ↵
      1. van Aken J,
      2. van Bilsen JH,
      3. Allaart CF,
      4. et al
      . The Leiden Early Arthritis Clinic. Clin Exp Rheumatol 2003;21(5 Suppl 31):S100–5.
      OpenUrlPubMedWeb of Science
    11. ↵
      1. Arnett FC,
      2. Edworthy SM,
      3. Bloch DA,
      4. et al
      . The American Rheumatism Association 1987 revised criteria for the classification of rheumatoid arthritis. Arthritis Rheum 1988;31:315–24.
      OpenUrlPubMedWeb of Science
    12. ↵
      1. Korendowych E,
      2. Owen P,
      3. Ravindran J,
      4. et al
      . The clinical and genetic associations of anti-cyclic citrullinated peptide antibodies in psoriatic arthritis. Rheumatology (Oxford) 2005;44:1056–60.
      OpenUrlAbstract/FREE Full Text
    13. ↵
      1. Candia L,
      2. Marquez J,
      3. Gonzalez C,
      4. et al
      . Low frequency of anticyclic citrullinated peptide antibodies in psoriatic arthritis but not in cutaneous psoriasis. J Clin Rheumatol 2006;12:226–9.
      OpenUrlCrossRefPubMedWeb of Science
    14. ↵
      1. Alenius GM,
      2. Berglin E,
      3. Rantapää Dahlqvist S
      . Antibodies against cyclic citrullinated peptide (CCP) in psoriatic patients with or without joint inflammation. Ann Rheum Dis 2006;65:398–400.
      OpenUrlAbstract/FREE Full Text

    Supplementary materials

    • Web Only Data ard.2009.108456

      Files in this Data Supplement:

    Footnotes

    • LD and MMT contributed equally to this work

    • Funding This work was supported by a EULAR Scientific Training Bursary to LD. The work is supported by the Netherlands Organisation for Health Research and Development, the Dutch Arthritis Association and grants from the European Commission (FP6 AutoCure and FP7 Masterswitch).

    • Competing interests None.

    • Patient consent Obtained.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Ethics approval This study was conducted with the approval of the Commissie Medische Ethiek (the Leiden institutional review board).