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Schumacher F, Zimmermann M, Kanbach M, Schulze W, Wollsching-Strobel M, Kroppen D, Stanzel SB, Majorski D, Windisch W, Strunk J, Berger M. Clinical relevance of positively determined myositis antibodies in rheumatology: a retrospective monocentric analysis. Arthritis Res Ther 2024; 26:132. [PMID: 39014499 PMCID: PMC11251291 DOI: 10.1186/s13075-024-03368-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 07/05/2024] [Indexed: 07/18/2024] Open
Abstract
BACKGROUND The increased availability of myositis autoantibodies represents new possibilities and challenges in clinical practice (Lundberg IE, Tjärnlund A, Bottai M, Werth VP, Pilkington C, de Visser M, et al. 2017 European League Against Rheumatism/American College of Rheumatology classification criteria for adult and juvenile idiopathic inflammatory myopathies and their major subgroups. Ann Rheum Dis. 2017;76:1955-64. https://doi.org/10.1136/annrheumdis-2017-211468 .). The aim of this study was to perform a retrospective data analysis of patient cases with positive myositis autoantibodies to analyse their significance in routine rheumatology practice. METHODS A monocentric analysis of all the orders used to determine myositis autoantibodies from July 2019 to May 2022 in the Department of Rheumatology, Krankenhaus Porz am Rhein, Cologne, Germany, was carried out. RESULTS In the defined time interval, a total of 71,597 laboratory values for the antibodies mentioned above were obtained. A total of 238 different positive autoantibodies were detected in 209 patients. Idiopathic inflammatory myopathy was diagnosed in 37 patients (18%), and inflammatory rheumatic diseases other than idiopathic inflammatory myopathy were diagnosed in 90 patients (43%). No inflammatory rheumatic disease was diagnosed in 82 patients (39%). General clusters of clinical manifestations were observed. CONCLUSIONS In our cohort, we were able to show that a relevant proportion of patients with positive myositis antibodies did not have idiopathic inflammatory myopathies or inflammatory rheumatic diseases. This finding indicates the importance of myositis autoantibodies in this group of patients. However, further studies on the course of symptoms and examination results in patients without inflammatory rheumatic diseases and with positive myositis antibodies are necessary.
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Affiliation(s)
- Falk Schumacher
- Department of Rheumatology, Krankenhaus Porz am Rhein, Cologne, Germany.
- Faculty of Health/School of Medicine, Witten/Herdecke University, Witten, Germany.
| | - Maximilian Zimmermann
- Department of Pneumology, Kliniken der Stadt Köln, Cologne, Germany
- Faculty of Health/School of Medicine, Witten/Herdecke University, Witten, Germany
| | - Malte Kanbach
- Faculty of Health/School of Medicine, Witten/Herdecke University, Witten, Germany
| | | | - Maximilian Wollsching-Strobel
- Department of Pneumology, Kliniken der Stadt Köln, Cologne, Germany
- Faculty of Health/School of Medicine, Witten/Herdecke University, Witten, Germany
| | - Doreen Kroppen
- Department of Pneumology, Kliniken der Stadt Köln, Cologne, Germany
- Faculty of Health/School of Medicine, Witten/Herdecke University, Witten, Germany
| | - Sarah Bettina Stanzel
- Department of Pneumology, Kliniken der Stadt Köln, Cologne, Germany
- Faculty of Health/School of Medicine, Witten/Herdecke University, Witten, Germany
| | - Daniel Majorski
- Department of Pneumology, Kliniken der Stadt Köln, Cologne, Germany
- Faculty of Health/School of Medicine, Witten/Herdecke University, Witten, Germany
| | - Wolfram Windisch
- Department of Pneumology, Kliniken der Stadt Köln, Cologne, Germany
- Faculty of Health/School of Medicine, Witten/Herdecke University, Witten, Germany
| | - Johannes Strunk
- Department of Rheumatology, Krankenhaus Porz am Rhein, Cologne, Germany
| | - Melanie Berger
- Department of Pneumology, Kliniken der Stadt Köln, Cologne, Germany
- Faculty of Health/School of Medicine, Witten/Herdecke University, Witten, Germany
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Chang YC, Yang L, Budhram A. Positive predictive value of myositis antibody line blot testing in patients with suspected idiopathic inflammatory myopathy. Muscle Nerve 2024; 69:626-630. [PMID: 38321821 DOI: 10.1002/mus.28050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 01/16/2024] [Accepted: 01/21/2024] [Indexed: 02/08/2024]
Abstract
INTRODUCTION/AIMS Line blot (LB) is in widespread use for myositis antibody detection. Yet, studies of its positive predictive value (PPV) in patients with suspected idiopathic inflammatory myopathy (IIM), which would be of particular relevance to neuromuscular clinicians, are lacking. We aimed to determine the PPV of myositis antibody LB testing in patients with suspected IIM, and examine whether PPV was significantly impacted by intensity of antibody positivity. METHODS This was a retrospective study of patients who underwent myositis antibody LB testing for suspected IIM between March 2019 and August 2022. RESULTS Of 70 patients who underwent testing for suspected IIM and had positive myositis antibody LB results, 43 (61%) were female and the median age was 61 years (range: 10-83 years). Forty-four were classified as true-positives, yielding a PPV of 63%. The PPV of patients with weak-positive myositis antibody results (14/30, 47%) was significantly lower than the PPV of patients with moderate-positive or strong-positive myositis antibody results (30/40, 75%) (p = .02). DISCUSSION Our study found that myositis antibody LB testing in patients with suspected IIM had a modest PPV, underscoring the need for antibody interpretation in the context of all available clinical and ancillary test data to avoid misdiagnosis. The significantly lower PPV in patients with weak-positive results emphasizes the particular importance of clinical correlation in such patients. Further study into the diagnostic performance of various LBs for myositis antibody detection is needed to inform their interpretation in clinical practice.
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Affiliation(s)
- Yiu-Chia Chang
- Department of Clinical Neurological Sciences, Western University, London Health Sciences Centre, London, Ontario, Canada
| | - Liju Yang
- Department of Pathology and Laboratory Medicine, Western University, London Health Sciences Centre, London, Ontario, Canada
| | - Adrian Budhram
- Department of Clinical Neurological Sciences, Western University, London Health Sciences Centre, London, Ontario, Canada
- Department of Pathology and Laboratory Medicine, Western University, London Health Sciences Centre, London, Ontario, Canada
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Ghirardello A, Gatto M, Franco C, Zanatta E, Padoan R, Ienna L, Gallo N, Zen M, Lundberg IE, Mahler M, Doria A, Iaccarino L. Detection of Myositis Autoantibodies by Multi-Analytic Immunoassays in a Large Multicenter Cohort of Patients with Definite Idiopathic Inflammatory Myopathies. Diagnostics (Basel) 2023; 13:3080. [PMID: 37835823 PMCID: PMC10572214 DOI: 10.3390/diagnostics13193080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 09/22/2023] [Accepted: 09/25/2023] [Indexed: 10/15/2023] Open
Abstract
BACKGROUND The usefulness of myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs) for the assessment of idiopathic inflammatory myopathies (IIMs) is acknowledged, but laboratory standardization remains a challenge. We detected MSAs/MAAs by multi-analytic line immunoassay (LIA) and particle-based multi-analyte technology (PMAT) in a multicenter cohort of patients with IIMs. METHODS We tested the sera from 411 patients affected with definite IIM, including 142 polymyositis (PM), 147 dermatomyositis (DM), 19 cancer-associated myositis, and 103 overlap myositis syndrome (OM), and from 269 controls. MSAs/MAAs were determined by 16Ags LIA in all sera, and anti-HMGCR by ELISA in 157/411 IIM sera and 91/269 control sera. The analytical specificity of LIA/HMGCR ELISA was compared with that of PMAT in 89 MSA+ IIM sera. RESULTS MSAs/MAAs were positive in 307/411 (75%) IIM patients and 65/269 (24%) controls by LIA (Odds Ratio 9.26, 95% CI 6.43-13.13, p < 0.0001). The sensitivity/specificity of individual MSAs/MAAs were: 20%/100% (Jo-1), 3%/99.3% (PL-7), 4%/98.8% (PL-12), 1%/100% (EJ), 0.7%/100% (OJ), 9%/98% (SRP), 5.6%/99.6% (TIF1γ), 4.6%/99.6% (MDA5), 8%/96% (Mi-2), 1.5%/98% (NXP2), 1.7%/100% (SAE1), 4%/92% (Ku), 8.5%/99% (PM/Scl-100), 8%/96% (PM/Scl-75), and 25.5%/79% (Ro52). Anti-HMGCR was found in 8/157 (5%) IIM patients and 0/176 (0%) controls by ELISA (p = 0.007). Concordance between LIA/HMGCR ELISA and PMAT was found in 78/89 (88%) samples. Individual MSAs detected by LIA were associated with IIM subsets: Jo-1 with PM and OM, PL-12 with OM, Mi-2, TIF1γ, and MDA5 with DM, SRP with PM, and PM/Scl-75/100 with OM (p < 0.001 for all). CONCLUSIONS Since MSAs are mostly mutually exclusive, multi-specific antibody profiling seems effective for a targeted clinical-serologic approach to the diagnosis of IIMs.
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Affiliation(s)
- Anna Ghirardello
- Rheumatology Unit, Department of Medicine-DIMED, University Hospital of Padova, 35128 Padova, Italy; (A.G.); (M.G.); (C.F.); (E.Z.); (R.P.); (L.I.); (M.Z.); (L.I.)
| | - Mariele Gatto
- Rheumatology Unit, Department of Medicine-DIMED, University Hospital of Padova, 35128 Padova, Italy; (A.G.); (M.G.); (C.F.); (E.Z.); (R.P.); (L.I.); (M.Z.); (L.I.)
- Rheumatology Unit, Department of Clinical and Biological Sciences, Mauriziano Hospital, University of Turin, 10124 Turin, Italy
| | - Chiara Franco
- Rheumatology Unit, Department of Medicine-DIMED, University Hospital of Padova, 35128 Padova, Italy; (A.G.); (M.G.); (C.F.); (E.Z.); (R.P.); (L.I.); (M.Z.); (L.I.)
| | - Elisabetta Zanatta
- Rheumatology Unit, Department of Medicine-DIMED, University Hospital of Padova, 35128 Padova, Italy; (A.G.); (M.G.); (C.F.); (E.Z.); (R.P.); (L.I.); (M.Z.); (L.I.)
| | - Roberto Padoan
- Rheumatology Unit, Department of Medicine-DIMED, University Hospital of Padova, 35128 Padova, Italy; (A.G.); (M.G.); (C.F.); (E.Z.); (R.P.); (L.I.); (M.Z.); (L.I.)
| | - Luana Ienna
- Rheumatology Unit, Department of Medicine-DIMED, University Hospital of Padova, 35128 Padova, Italy; (A.G.); (M.G.); (C.F.); (E.Z.); (R.P.); (L.I.); (M.Z.); (L.I.)
| | - Nicoletta Gallo
- Unit of Laboratory Medicine, Department of Medicine-DIMED, University Hospital of Padova, 35128 Padova, Italy;
| | - Margherita Zen
- Rheumatology Unit, Department of Medicine-DIMED, University Hospital of Padova, 35128 Padova, Italy; (A.G.); (M.G.); (C.F.); (E.Z.); (R.P.); (L.I.); (M.Z.); (L.I.)
| | - Ingrid E. Lundberg
- Rheumatology Unit, Department of Medicine, Karolinska University Hospital in Solna, Karolinska Institutet, 171 77 Stockholm, Sweden;
| | | | - Andrea Doria
- Rheumatology Unit, Department of Medicine-DIMED, University Hospital of Padova, 35128 Padova, Italy; (A.G.); (M.G.); (C.F.); (E.Z.); (R.P.); (L.I.); (M.Z.); (L.I.)
| | - Luca Iaccarino
- Rheumatology Unit, Department of Medicine-DIMED, University Hospital of Padova, 35128 Padova, Italy; (A.G.); (M.G.); (C.F.); (E.Z.); (R.P.); (L.I.); (M.Z.); (L.I.)
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