Diagnostic performance and predictive value of serum markers for the diagnosis of rheumatoid arthritis

  • IEA Hoffman1,

    Affiliated with

    • I Peene1,

      Affiliated with

      • A Union2,

        Affiliated with

        • L Meheus2,

          Affiliated with

          • L De Clercq3,

            Affiliated with

            • L Schatteman3,

              Affiliated with

              • S Poriau4,

                Affiliated with

                • H Mielants1, 3,

                  Affiliated with

                  • EM Veys1 and

                    Affiliated with

                    • F De Keyser1, 4

                      Affiliated with

                      Arthritis Res Ther20046(Suppl 1):17

                      DOI: 10.1186/ar1059

                      Received: 16 January 2004

                      Published: 24 February 2004

                      Background

                      Rheumatoid factor (RF) is the classical serum marker for rheumatoid arthritis (RA). Anti-citrullinated peptide antibodies (ACPA) have a higher sensitivity and specificity (spec) for RA.

                      Objective

                      Our aim was to evaluate the diagnostic and predictive value for RA of RF and antibodies to pepA and pepB (two synthetic substrates for ACPA detection) in a setting relevant to routine clinical practice.

                      Methods

                      In this prospective multicentre study, samples were collected at academic and nonacademic centres from 1003 consecutive patients presenting for diagnostic work-up when the clinician included RA in the differential diagnosis. RF was detected by latex fixation. A research INNO-LIA™ RA (Innogenetics, Belgium) was used to detect anti-pepA and anti-pepB antibodies. Diagnoses were made by the clinician using ACR criteria after 1 year follow-up. ROC curve analysis was used to evaluate the diagnostic performance of the tests.

                      Results

                      The following diagnoses were made: definite RA (n = 144), non-RA (n = 629), undifferentiated (n = 156), and lost to follow up (n = 74). The first two groups were used to determine sensitivity, specificity, and positive predictive value (PPV). ROC curve analysis (Fig. 1) showed a higher area under the curve for RF than for anti-pepA and anti-pepB antibodies (0.839 versus 0.784 and 0.788, respectively), but in the high specificity region anti-pepA and anti-pepB antibodies performed better than RF (Table 1).
                      http://static-content.springer.com/image/art%3A10.1186%2Far1059/MediaObjects/13075_2004_Article_1049_Fig1_HTML.jpg
                      Figure 1

                      ROC curves.

                      Table 1

                      Diagnostic performance of serum markers using different cut offs

                      Antibody

                      Cutoff

                      Sensitivity (%)

                      Specificity (%)

                      PPV (%)

                      PepA

                      Low

                      63.6

                      90.6

                      60.7

                      PepB

                       

                      64.3

                      90.0

                      59.0

                      RF

                       

                      69.2

                      90.1

                      61.5

                      PepA

                      Intermediate

                      62.9

                      95.1

                      74.4

                      PepB

                       

                      61.5

                      95.1

                      73.3

                      RF

                       

                      55.2

                      94.6

                      69.9

                      PepA

                      High

                      58.7

                      98.1

                      87.5

                      PepB

                       

                      48.3

                      98.1

                      85.2

                      RF

                       

                      42.0

                      97.8

                      81.1

                      PepA

                      Very high

                      41.3

                      99.0

                      90.8

                      PepB

                       

                      37.1

                      99.0

                      89.8

                      RF

                       

                      21.0

                      99.0

                      83.3

                      Conclusion

                      When high specificity is required, anti-pepA and anti-pepB antibodies have a markedly higher sensitivity than RF. The highest PPV are found when ACPA are very high.

                      Authors’ Affiliations

                      (1)
                      Rheumatology, Gent University Hospital
                      (2)
                      Innogenetics
                      (3)
                      Rheumatology, St-Augustinus Hospital
                      (4)
                      Locomotion Center, Elisabeth Hospital

                      Copyright

                      © BioMed Central Ltd 2004

                      Advertisement