Line blot immunoassays in idiopathic inflammatory myopathies: retrospective review of diagnostic accuracy and factors predicting true positive results.
Idiopathic inflammatory myopathy
Immunoblotting; myositis; autoantibodies
Inflammatory muscle disease
Line blot immunoassay
Journal
BMC rheumatology
ISSN: 2520-1026
Titre abrégé: BMC Rheumatol
Pays: England
ID NLM: 101738571
Informations de publication
Date de publication:
2020
2020
Historique:
received:
14
01
2020
accepted:
05
04
2020
entrez:
24
7
2020
pubmed:
24
7
2020
medline:
24
7
2020
Statut:
epublish
Résumé
Line blot immunoassays (LIA) for myositis-specific (MSA) and myositis-associated (MAA) autoantibodies have become commercially available. In the largest study of this kind, we evaluated the clinical performance of a widely used LIA for MSAs and MAAs. Adults tested for MSA/MAA by LIA at a tertiary myositis centre (January 2016-July 2018) were identified. According to expert-defined diagnoses, true and false positive rates were calculated for strongly and weakly positive autoantibody results within three cohorts: idiopathic inflammatory myopathy (IIM), connective tissue disease (CTD) without myositis, and non-CTD/IIM. Factors associated with true positivity were determined. We analysed 342 cases. 67 (19.6%) had IIM, in whom 71 autoantibodies were detected (50 strong positives [70.4%], 21 weak positives [29.6%]). Of the strong positives, 48/50 (96.0%; 19 MSAs, 29 MAAs) were deemed true positives. Of the weak positives, 15/21 (71.4%; 3 MSAs, 12 MAAs) were deemed true positives.In CTD without myositis cases ( We demonstrated the high specificity of a myositis LIA in a clinical setting. However, a significant burden of false positive results was evident in those with a low pre-test likelihood of IIM and for weakly positive autoantibodies.
Sections du résumé
BACKGROUND
BACKGROUND
Line blot immunoassays (LIA) for myositis-specific (MSA) and myositis-associated (MAA) autoantibodies have become commercially available. In the largest study of this kind, we evaluated the clinical performance of a widely used LIA for MSAs and MAAs.
METHODS
METHODS
Adults tested for MSA/MAA by LIA at a tertiary myositis centre (January 2016-July 2018) were identified. According to expert-defined diagnoses, true and false positive rates were calculated for strongly and weakly positive autoantibody results within three cohorts: idiopathic inflammatory myopathy (IIM), connective tissue disease (CTD) without myositis, and non-CTD/IIM. Factors associated with true positivity were determined.
RESULTS
RESULTS
We analysed 342 cases. 67 (19.6%) had IIM, in whom 71 autoantibodies were detected (50 strong positives [70.4%], 21 weak positives [29.6%]). Of the strong positives, 48/50 (96.0%; 19 MSAs, 29 MAAs) were deemed true positives. Of the weak positives, 15/21 (71.4%; 3 MSAs, 12 MAAs) were deemed true positives.In CTD without myositis cases (
CONCLUSIONS
CONCLUSIONS
We demonstrated the high specificity of a myositis LIA in a clinical setting. However, a significant burden of false positive results was evident in those with a low pre-test likelihood of IIM and for weakly positive autoantibodies.
Identifiants
pubmed: 32699830
doi: 10.1186/s41927-020-00132-9
pii: 132
pmc: PMC7370419
doi:
Types de publication
Journal Article
Langues
eng
Pagination
28Subventions
Organisme : Medical Research Council
ID : MR/N003322/1
Pays : United Kingdom
Informations de copyright
© The Author(s) 2020.
Déclaration de conflit d'intérêts
Competing interestsHC is an Associate Editor of BMC Rheumatology.
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