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Rönnelid J, Turesson C, Kastbom A. Autoantibodies in Rheumatoid Arthritis - Laboratory and Clinical Perspectives. Front Immunol 2021; 12:685312. [PMID: 34054878 PMCID: PMC8161594 DOI: 10.3389/fimmu.2021.685312] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 04/20/2021] [Indexed: 01/03/2023] Open
Abstract
Measurement of two groups of autoantibodies, rheumatoid factor (RF) and anti-citrullinated protein/peptide antibodies (ACPA) have gained increasing significance in the diagnosis and classification of rheumatoid arthritis (RA) over the last 65 years. Despite this rising importance of autoimmune serology in RA, there is a palpable lack of harmonization between different commercial RF and ACPA tests. While a minimal diagnostic specificity has been defined for RF tests, which almost always are related to an international reference preparation, neither of this applies to ACPA. Especially assays with low diagnostic specificity are associated with very low positive predictive values or post-test probabilities in real world settings. In this review we focus on issues of practical bearing for the clinical physician diagnosing patients who potentially have RA, or treating patients diagnosed with RA. We advocate that all clinically used assays for RF and ACPA should be aligned to a common diagnostic specificity of 98-99% compared to healthy controls. This high and rather narrow interval corresponds to the diagnostic specificity seen for many commercial ACPA tests, and represents a specificity that is higher than what is customary for most RF assays. Data on antibody occurrence harmonized in this way should be accompanied by test result-specific likelihood ratios for the target diagnosis RA on an ordinal or interval scale, which will provide the clinical physician with more granular and richer information than merely relating numerical values to a single cut-off point. As many physicians today are used to evaluate autoantibodies as positive or negative on a nominal scale, the introduction of test result-specific likelihood ratios will require a change in clinical mindset. We also discuss the use of autoantibodies to prognosticate future arthritis development in at-risk patients as well as predict severe disease course and outcome of pharmacological treatment.
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Affiliation(s)
- Johan Rönnelid
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden.,Department of Clinical Immunology and Transfusion Medicine, Uppsala University Hospital, Uppsala, Sweden
| | - Carl Turesson
- Rheumatology, Department of Clinical Sciences, Malmö, Lund University, Malmö, Sweden.,Department of Rheumatology, Skåne University Hospital, Malmö, Sweden
| | - Alf Kastbom
- Department of Rheumatology, Linköping University Hospital, Linköping, Sweden.,Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
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Westra J, Brouwer E, Raveling-Eelsing E, Arends S, Eman Abdulle A, Roozendaal C, van Delft MAM, Toes REM, Trouw LA, Vissink A, de Smit MJ. Arthritis autoantibodies in individuals without rheumatoid arthritis: follow-up data from a Dutch population-based cohort (Lifelines). Rheumatology (Oxford) 2021; 60:658-666. [PMID: 32594174 PMCID: PMC7850523 DOI: 10.1093/rheumatology/keaa219] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 03/19/2020] [Indexed: 12/20/2022] Open
Abstract
OBJECTIVES To assess whether the presence of arthritis autoantibodies alongside IgG ACPA predicts clinically suspect arthralgia in ACPA-positive subjects without RA. METHODS In the population-based Lifelines cohort (n = 40 136), 308 IgG ACPA-positive individuals without RA were present. Serum levels of IgA ACPA, IgA and IgM RF, and IgG anti-carbamylated antibodies were measured at baseline. Individuals were divided based on the Connective tissue disease Screening Questionnaire after 2 years follow-up. Antibodies to Porphyromonas gingivalis were determined at baseline and related to presence of periodontitis and joint complaints at 2 years follow-up. RESULTS Of 308 subjects 53.6% were also seropositive for IgA ACPA, 42.2% for IgM RF, 23.7% for IgA RF and 13.6% for anti-carbamylated antibodies. We defined 75 persons with clinically suspect arthralgia at risk for RA based on CTD Screening Questionnaire at follow-up. Significantly more seropositivity for IgM RF and higher levels of IgG ACPA, IgA ACPA and IgM RF were found in clinically suspect arthralgia compared with no-clinically suspect arthralgia. In multivariate logistic regression correcting for age, gender and never smoking, positivity for three or more extra autoantibodies was significantly associated with clinically suspect arthralgia. Although levels of anti-P. gingivalis were not different between groups, they were significantly correlated to levels of both RFs, and both ACPAs in clinically suspect arthralgia. CONCLUSIONS ACPA-positive individuals without RA who develop clinically suspect arthralgia have more and higher levels of other arthritis autoantibodies at baseline. Levels of anti-P. gingivalis are not related to self-reported periodontitis or clinically suspect arthralgia, but are correlated to arthritis autoantibodies in clinically suspect arthralgia.
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Affiliation(s)
- Johanna Westra
- Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Elisabeth Brouwer
- Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Elisabeth Raveling-Eelsing
- Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Suzanne Arends
- Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Amaal Eman Abdulle
- Department of Internal Medicine, Division Vascular Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Caroline Roozendaal
- Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Myrthe A M van Delft
- Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands
| | - Rene E M Toes
- Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands
| | - Leendert A Trouw
- Department of Rheumatology, Leiden University Medical Center, Leiden, The Netherlands
| | - Arjan Vissink
- Department of Oral and Maxillofacial Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Menke J de Smit
- Department of Rheumatology and Clinical Immunology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.,Department of Oral and Maxillofacial Surgery, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
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