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Loganathan A, Gupta L, Rudge A, Lu H, Bowler E, McMorrow F, Naveen R, Anuja AK, Agarwal V, McHugh N, Tansley S. Assessing the sensitivity and specificity of myositis-specific and associated autoantibodies: a sub-study from the MyoCite cohort. Rheumatology (Oxford) 2024; 63:2363-2371. [PMID: 38479813 DOI: 10.1093/rheumatology/keae167] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2023] [Accepted: 02/19/2024] [Indexed: 09/05/2024] Open
Abstract
OBJECTIVES Myositis-specific and associated autoantibodies are important biomarkers in routine clinical use. We assessed local testing performance for myositis autoantibodies by comparing line immunoassay (LIA) to protein radio-immunoprecipitation and identifying clinical characteristics associated with each myositis autoantibody in the MyoCite cohort. METHODS Serum samples from patients within the MyoCite cohort, a well-characterized retro-prospective dataset of adult and juvenile idiopathic inflammatory myopathy (IIM) patients in Lucknow, India (2017-2020), underwent LIA at Sanjay Gandhi Postgraduate Institute of Medical Science (SGPGIMS), Lucknow. Immunoprecipitation of 147 IIM patients' serum samples (125 adult-onset, 22 juvenile-onset) was conducted at the University of Bath, with researchers blind to LIA results. LIA performance was assessed against immunoprecipitation as the reference standard, measuring sensitivity, specificity and inter-rater agreement. Univariate and multivariate logistic regression determined clinical associations for specific myositis-specific autoantibodies. RESULTS Immunoprecipitation identified myositis autoantibodies in 56.5% (n = 83) of patient samples, with anti-Jo1 (n = 16; 10.9%) as the most common, followed by anti-MDA5 (n = 14, 9.5%). While LIA showed good agreement for anti-Jo1, anti-PL7 and anti-PL12 (Cohen's κ 0.79, 0.83 and 1, respectively), poor agreement was observed in other subgroups, notably anti-TIF1γ (Cohen's κ 0.21). Strongly positive samples, especially in myositis-specific autoantibodies, correlated more with immunoprecipitation results. Overall, 59 (40.1%) samples exhibited non-congruence on LIA and immunoprecipitation, and κ values for LIAs for anti-TIF1γ, anti-Ku, anti-PmScl, anti-Mi2 and anti-SAE ranged between 0.21 and 0.60. CONCLUSION While LIA reliably detected anti-Jo1, anti-PL7, anti-PL12, anti-MDA5 and anti-NXP-2, it also displayed false positives and negatives. Its effectiveness in detecting other autoantibodies, such as anti-TIF1γ, was poor.
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Affiliation(s)
- Aravinthan Loganathan
- Royal National Hospital of Rheumatic Diseases, Royal United Hospitals Bath NHS Foundation Trust, Bath, UK
- Department of Life Sciences, University of Bath, Bath, UK
| | - Latika Gupta
- Department of Clinical Immunology and Rheumatology, SGPGIMS, Lucknow, India
- Department of Rheumatology, Royal Wolverhampton Hospital NHS Trust, Wolverhampton, UK
- Division of Musculoskeletal and Dermatological Sciences, Centre for Musculoskeletal Research, School of Biological Sciences, The University of Manchester, Manchester, UK
| | - Alex Rudge
- Department of Mathematical Sciences, University of Bath, Bath, UK
| | - Hui Lu
- Department of Life Sciences, University of Bath, Bath, UK
| | | | | | - R Naveen
- Department of Clinical Immunology and Rheumatology, SGPGIMS, Lucknow, India
| | - Anamika K Anuja
- Department of Clinical Immunology and Rheumatology, SGPGIMS, Lucknow, India
| | - Vikas Agarwal
- Department of Clinical Immunology and Rheumatology, SGPGIMS, Lucknow, India
| | - Neil McHugh
- Department of Life Sciences, University of Bath, Bath, UK
| | - Sarah Tansley
- Royal National Hospital of Rheumatic Diseases, Royal United Hospitals Bath NHS Foundation Trust, Bath, UK
- Department of Life Sciences, University of Bath, Bath, UK
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McMorrow FK, Anwyll N, Tansley SL. Autoantibody testing in myositis: an update. Curr Opin Rheumatol 2024:00002281-990000000-00134. [PMID: 39155767 DOI: 10.1097/bor.0000000000001039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/20/2024]
Abstract
PURPOSE OF REVIEW This review aims to provide an update on myositis autoantibody testing strategies. We have focussed on the reliability and usefulness of different myositis autoantibody detection methods, including commonly used solid phase immunoassays and newer discovery techniques. RECENT FINDINGS Several studies have highlighted the limitations of currently available immunoassays, particularly when used in populations with low pretest probability and without supporting clinical evidence. While many autoantibodies, such as anti-Jo1, are detected with high sensitivity and specificity, the low incidence of myositis autoantibodies in tested populations reduces their positive predictive value. The low sensitivity of line immunoassays to detect key myositis autoantibodies, including anti-TIF1γ and rarer antisynthetase autoantibodies, is a concern. SUMMARY Myositis autoantibodies are widely accepted as important clinical tools, and hence, there is a significant demand for reliable, accessible, and affordable detection methods. False positives and negative results have the potential to impact on patient care, particularly for malignancy and lung disease associated autoantibodies. Increased availability of myositis autoantibody testing has led to a rise in requests from a broader range of clinicians. It is critically important that clinicians are aware of specific limitations of tests and interpret results in the context of clinical findings.
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Affiliation(s)
| | - Natalie Anwyll
- Royal National Hospital for Rheumatic Diseases, Royal United Hospitals, Bath, UK
| | - Sarah L Tansley
- Department of Life Sciences, University of Bath
- Royal National Hospital for Rheumatic Diseases, Royal United Hospitals, Bath, UK
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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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Loarce-Martos J, Calvo Sanz L, Garrote-Corral S, Ballester González R, Pariente Rodríguez R, Rita CG, García-Soidan A, Bachiller-Corral J, Roy Ariño G. Myositis autoantibodies detected by line blot immunoassay: clinical associations and correlation with antibody signal intensity. Rheumatol Int 2023; 43:1101-1109. [PMID: 36763166 DOI: 10.1007/s00296-023-05279-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 01/15/2023] [Indexed: 02/11/2023]
Abstract
The aim of this study is to assess the relationship between myositis specific (MSA) and myositis associated (MAA) antibodies and diagnosis (including idiopathic inflammatory myopathies [IIM] and other systemic autoimmune diseases [SAID]), and to explore the impact of antibody signal intensity in diagnostic accuracy. We retrospectively reviewed all the serum samples obtained from patients tested for MSA/MAA by line immunoassay (LIA) between 01/01/2018 and 31/12/2020 in Ramón y Cajal University Hospital (Spain). Clinical true positive (CTP) MSAs and MAAs were defined as those patients with IIM or SAID with phenotypes expected of that MSA/MAA. Patients who did not have a phenotype compatible with that antibody were classified as clinical false positive (CFP). One hundred and thirty positive samples were analysed. Forty-six patients (33.38%) were classified as IIM, forty-two (32.3%) as SAID and forty-two (32.3%) as non-IIM/SAID. Among these 130 patients, 164 MSA/MAA were detected. Eighty-five (51.8%) positive MSA/MAA were classified as CTP, and seventy-nine (48.2%) as CFP. Strongly positive antibodies were more frequently CTP (35/47, 74.5%) than weak positives (54/68, 36.8%), (p ˂ 0.001). Antibodies classified as CTP had a higher signal intensity than CFP (36.77 AU vs 20.00 AU, CI95% 7.79-22.09, p ˂ 0.001). The probability of a CFP was associated to negative ANA, low ANA titer, and multiple positive MSA/MAA (p ˂ 0.001). In this study, we confirmed that CFP results using LIA are frequent, and are associated with low signal intensity MSA/MAA, negative ANA, lower titer ANA, and with multiple positive samples.
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Affiliation(s)
- Jesús Loarce-Martos
- Department of Rheumatology, Hospital Universitario Ramón y Cajal, Madrid, Spain.
| | - Laura Calvo Sanz
- Department of Rheumatology, Hospital Universitario Ramón y Cajal, Madrid, Spain
| | | | | | | | | | - Ana García-Soidan
- Department of Immunology, Hospital Universitario Ramón y Cajal, Madrid, Spain
| | | | - Garbiñe Roy Ariño
- Department of Immunology, Hospital Universitario Ramón y Cajal, Madrid, Spain
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Damoiseaux J, Mammen AL, Piette Y, Benveniste O, Allenbach Y. 256 th ENMC international workshop: Myositis specific and associated autoantibodies (MSA-ab): Amsterdam, The Netherlands, 8-10 October 2021. Neuromuscul Disord 2022; 32:594-608. [PMID: 35644723 DOI: 10.1016/j.nmd.2022.05.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 05/12/2022] [Accepted: 05/17/2022] [Indexed: 10/18/2022]
Affiliation(s)
- Jan Damoiseaux
- Central Diagnostic Laboratory, Maastricht University Medical Center, Maastricht, the Netherlands.
| | - Andrew L Mammen
- Muscle Disease Unit. Laboratory of Muscle Stem Cells and Gene Regulation, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, United States
| | - Yves Piette
- Department of Rheumatology, Ghent University Hospital, Ghent, Belgium; Department of Internal Medicine, Ghent University, Ghent, Belgium
| | - Olivier Benveniste
- Department of Internal Medicine and Clinical Immunology, Sorbonne Université, INSERM, UMR974, Pitié-Salpêtrière University Hospital, Paris, France
| | - Yves Allenbach
- Department of Internal Medicine and Clinical Immunology, Sorbonne Université, INSERM, UMR974, Pitié-Salpêtrière University Hospital, Paris, France
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Ferreira BSDA, Cunha BMD, Moreira LA, Fonseca MFSE, Cavalcante EBU. Comments: Myositis-specific and myositis-associated autoantibody profiles and their clinical associations in a large series of patients with polymyositis and dermatomyositis. Clinics (Sao Paulo) 2022; 77:100077. [PMID: 35882105 PMCID: PMC9326124 DOI: 10.1016/j.clinsp.2022.100077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 06/27/2022] [Indexed: 11/16/2022] Open
Affiliation(s)
| | - Bernardo Matos da Cunha
- Centro Universitário do Planalto Central Apparecido dos Santos (UNICEPLAC), Brasília, DF, Brazil
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