Myositis autoantibodies detected by line blot immunoassay: clinical associations and correlation with antibody signal intensity

Loarce-Martos, Jesús; Sanz, Laura Calvo; Garrote-Corral, Sandra; Ballester-González, Rubén; Pariente, Roberto; Rita, Claudia Geraldine; García-Soidán, Ana; Bachiller‐Corral, Javier; Ariño, Garbiñe Roy

doi:10.1007/s00296-023-05279-5

Cited by 2 publications

(4 citation statements)

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“…In our study, we found the PPV to be 63%, which is higher than previous reports that have estimated a PPV of 50% or lower 9–11 . The higher PPV in our study, which excluded patients in whom there was not concern for muscle disease, might be due to a higher prevalence of the disease in our tested population and demonstrates the necessity of specifying the tested population in studies of PPV.…”

Section: Discussioncontrasting

confidence: 81%

“…In our study, we found the PPV to be 63%, which is higher than previous reports that have estimated a PPV of 50% or lower. [9][10][11] The higher PPV in our study, which excluded patients in whom there was not concern for muscle disease, might be due to a higher prevalence of the disease in our tested population and demonstrates the necessity of specifying the tested population in studies of PPV. Nonetheless, the findings of our study suggest that over one-third of patients with positive myositis antibody LB results who underwent testing for suspected IIM may harbor false-positive antibody results, which can contribute to incorrect diagnosis and inappropriate treatment with potentially hazardous immunotherapy.…”

Section: Discussionmentioning

confidence: 77%

“…One such evaluation that is practically useful to the clinician is determination of test positive predictive value (PPV), which refers to the probability that a patient with a positive result truly has the disease of interest 8 . Recent studies investigating the diagnostic performance of myositis antibody LB, which included patients with and without suspected IIM who may have undergone testing for other indications (e.g., suspected inflammatory lung or skin disease), have estimated a concerningly low PPV of 50% or lower 9–11 . Importantly, however, PPV is dependent on disease prevalence in the tested population; as prevalence decreases, so too does PPV 8 .…”

Section: Introductionmentioning

confidence: 99%

“…8 Recent studies investigating the diagnostic performance of myositis antibody LB, which included patients with and without suspected IIM who may have undergone testing for other indications (e.g., suspected inflammatory lung or skin disease), have estimated a concerningly low PPV of 50% or lower. [9][10][11] Importantly, however, PPV is dependent on disease prevalence in the tested population; as prevalence decreases, so too does PPV. 8 The PPV of myositis antibody LB testing may therefore be higher when specifically evaluated in patients with suspected IIM, due to the possibly higher disease prevalence in the tested population.…”

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confidence: 99%

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Positive predictive value of myositis antibody line blot testing in patients with suspected idiopathic inflammatory myopathy

Chang,

Yang,

Budhram

2024

Muscle and Nerve

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Introduction/AimsLine 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.MethodsThis was a retrospective study of patients who underwent myositis antibody LB testing for suspected IIM between March 2019 and August 2022.ResultsOf 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).DiscussionOur 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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Section: Discussioncontrasting

confidence: 81%

Section: Discussionmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Positive predictive value of myositis antibody line blot testing in patients with suspected idiopathic inflammatory myopathy

Chang,

Yang,

Budhram

2024

Muscle and Nerve

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Detection of Myositis Autoantibodies by Multi-Analytic Immunoassays in a Large Multicenter Cohort of Patients with Definite Idiopathic Inflammatory Myopathies

Ghirardello,

Gatto,

Franco

et al. 2023

Diagnostics

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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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Myositis autoantibodies detected by line blot immunoassay: clinical associations and correlation with antibody signal intensity

Cited by 2 publications

References 45 publications

Positive predictive value of myositis antibody line blot testing in patients with suspected idiopathic inflammatory myopathy

Positive predictive value of myositis antibody line blot testing in patients with suspected idiopathic inflammatory myopathy

Detection of Myositis Autoantibodies by Multi-Analytic Immunoassays in a Large Multicenter Cohort of Patients with Definite Idiopathic Inflammatory Myopathies

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