Classification Criteria For Idiopathic Inflammatory Myopathies Research Articles

Autoantibody evaluation in idiopathic inflammatory myopathies.

Idiopathic inflammatory myopathies (IIM), generally referred to as myositis is a heterogeneous group of diseases characterized by muscle inflammation and/or skin involvement, diverse extramuscular manifestations with variable risk for malignancy and response to treatment. Contemporary clinico-serologic categorization identifies 5 main clinical groups which can be further stratified based on age, specific clinical manifestations and/or risk for cancer. The serological biomarkers for this classification are generally known as myositis-specific (MSAs) and myositis-associated antibodies. Based on the use of these antibodies, IIM patients are classified into anti-synthetase syndrome, dermatomyositis, immune-mediated necrotizing myopathy, inclusion body myositis, and overlap myositis. The current classification criteria for IIM requires clinical findings, laboratory measurements, and histological findings of the muscles. However, the use MSAs and myositis-associated autoantibodies as an adjunct for disease evaluation is thought to provide a cost-effective personalized approach that may not only guide diagnosis but aid in stratification and/or prognosis of patients. This review provides a comprehensive overview of contemporary autoantibodies that are specific or associated myositis. In addition, it highlights possible pathways for the detection and interpretation of these antibodies with limitations for routine clinical use.

Performance of the 2017 EULAR/ACR criteria for idiopathic inflammatory myopathies in a cohort of patients from Latin America.

We aimed to determine the performance of the 2017 European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria for idiopathic inflammatory myopathies (IIMs) in a cohort of Chilean patients. This single-center retrospective study included 151 patients with a clinical diagnosis of IIM. Patients were classified according to the 2017 EULAR/ACR classification criteria for IIM, and its performance was compared to the Bohan & Peter (B&P) classification criteria. A total of 135 patients (89.4%) met the EULAR/ACR criteria, and 140 (92.7%) patients met the B&P criteria. A total of 130 patients had IIM according to both the criteria; concordance rate was 29.2% for definite IIM, 6.2% for probable IIM, and 1.5% for possible IIM. The kappa coefficient of agreement was weak between the 2 classification criteria (κ = 0.39, SD 0.15-0.64). Against gold standard expert physician's diagnosis, sensitivity, and specificity of EULAR/ACR criteria was 0.86 and 0.85 to diagnose dermatomyositis, respectively, and 0.73 and 0.87 to diagnose polymyositis. The EULAR/ACR criteria showed good sensitivity and identified more patients with probable or definite IIM than the B&P criteria in a single-center cohort of patients with IIM in South America. The sensitivity of the EULAR/ACR criteria was slightly higher in patients with dermatomyositis, but lower in patients with polymyositis, than that of the B&P criteria.

Performance of the 2017 European Alliance of Associations for Rheumatology/American College of Rheumatology Classification Criteria in Patients With Idiopathic Inflammatory Myopathy and Anti-Melanoma Differentiation-Associated Protein 5 Positivity.

This study aimed to evaluate whether the 2017 European Alliance of Associations for Rheumatology (EULAR)/American College of Rheumatology (ACR) classification criteria for adult and juvenile idiopathic inflammatory myopathies (IIMs) could appropriately classify the diagnosis in adult patients with anti-melanoma differentiation-associated protein 5 (anti-MDA-5)-positive IIM. In addition, this study sought to determine whether a status of anti-MDA-5 positivity could be incorporated into the EULAR/ACR IIM classification criteria set and whether the recently modified criteria based on the presence of myositis-specific autoantibodies (MSAs) could be used to appropriately classify the diagnosis in patients with anti-MDA-5-positive IIM. Consecutive adult patients clinically diagnosed as having anti-MDA-5-positive IIM from 10 hospitals in Hong Kong were retrospectively recruited; patient characteristics were obtained from electronic medical records. We used a commercial line blot immunoassay to detect MSAs. We also determined a proposed set of phenotypic-serologic classification criteria specific for anti-MDA-5. In the patient cohort (n=120; 31.7% with dermatomyositis, 68.3% with clinically amyopathic dermatomyositis [CADM]), the diagnosis could be classified with the EULAR/ACR criteria in 86 patients (71.7%) and with the Bohan and Peter criteria in 49 patients (40.8%). However, when combined with criteria specifically modified for CADM, the diagnosis could be classified by the Bohan and Peter criteria in 76.7% of patients. We observed that the sensitivity of the EULAR/ACR criteria could be improved to 98.3% if anti-MDA-5 antibody-positive status was considered as one of the criteria. The MSA-based criteria had 100% sensitivity. When we applied our proposed specific phenotypic-serologic criteria for the classification of patients with anti-MDA-5 antibodies, 97.5% of patients were able to be classified as having IIM. In this cohort of patients with anti-MDA-5-positive IIM, the diagnosis could not be classified by the EULAR/ACR criteria in almost 30% of patients. We suggest incorporating anti-MDA-5 antibody positivity as a criterion into existing criteria sets or developing specific criteria for patients with anti-MDA-5-positive IIM.

External validation of the EULAR/ACR idiopathic inflammatory myopathies classification criteria witha Japanese paediatric cohort.

To assess the performance of the EULAR/ACR idiopathic inflammatory myopathies (IIMs) classification criteria to classify juvenile IIMs (JIIMs) in an Asian paediatric population. Sixty-eight JIIM patients and 49 non-JIIM patients diagnosed at seven major paediatric rheumatology centres in Japan between 2008 and 2015 were enrolled. Retrospective data were collected, and each patient's data form was submitted. The expert group reviewed the forms and re-examined the diagnoses. The EULAR/ACR criteria were then applied and the probability of having JIIM was determined for each case. The sensitivity and specificity of the EULAR/ACR criteria were compared with those of other existing criteria. The sensitivity/specificity of the EULAR/ACR classification criteria were 92.1/100% with muscle biopsy data (n = 38); 86.7/100% without muscle biopsy data (n = 30) and 89.7/100% in our total cohort (n = 68). The sensitivity of Bohan and Peter's criteria and Tanimoto's criteria were 80.9 and 64.7% in our total cohort, respectively. Among 68 physician-diagnosed JIIM patients, seven cases (three JDM and four overlap myositis) were not classified as JIIM because the probability did not reach the cut-off point (55%). The three JDM patients all presented with only one of the three skin manifestations that are listed in the criteria: Gottron's sign. Our validation study with Japanese JIIM cases indicates that the EULAR/ACR classification criteria for IIM generally perform better than existing diagnostic criteria for myositis.

Can machine learning unravel the complex IIM spectrum?

Idiopathic inflammatory myopathies (IIMs) are heterogeneous conditions, and the optimal way to classify patients and divide them into subgroups remains unclear. Could machine learning techniques be the answer to the problem of defining homogeneous disease phenotypes, enabling stratified treatment approaches and the formulation of future IIM classification criteria?

Inflammatory muscle disease – An update

Idiopathic inflammatory myopathies (IIM) are a heterogeneous group of inflammatory myopathies whose common feature is immune-mediated muscle injury. There are distinct subgroups including dermatomyositis (DM), polymyositis (PM), inclusion body myositis, and immune-mediated necrotizing myopathy. Antisynthetase syndrome is also emerging as a distinct subgroup with its unique muscle histopathological characteristic of perifascicular necrosis. While the newly updated EULAR/ACR Classification Criteria for IIM have brought advancements in diagnosis and the exclusion of mimickers, the use of only one autoantibody in the derivation of the schema limits its use. Similarly, while the advent of multiple novel therapeutics in the treatment of myositis has been exciting, it has also highlighted the scarcity of validated outcome measures. The purpose of our review is to highlight the updated classification criteria of myositis, newly reported clinical phenotypes associated with myositis autoantibodies, the measurement of outcomes, and emerging treatments in the field.

The performance of the European League Against Rheumatism/American College of Rheumatology idiopathic inflammatory myopathies classification criteria in an expert-defined 10 year incident cohort.

ObjectivesTo assess the performance of the EULAR/ACR idiopathic inflammatory myopathies (IIMs) classification criteria in a cohort of incident IIM cases and examine how criteria-assigned IIM subtype correlates with expert opinion.MethodsAdults with newly diagnosed IIM attending Salford Royal NHS Foundation Trust were identified over a 10 year period. A retrospective review of all putative cases was performed and those fulfilling a consensus expert opinion diagnosis of IIM were included. Clinical, serological and histological data were collected and each case was assigned a single IIM subtype. The EULAR/ACR classification criteria were then applied and sensitivity, specificity and positive and negative predictive values were calculated, presented with 95% CIs.ResultsA total of 1637 cases were screened, with 255 consensus expert opinion IIM cases ultimately identified. Applying the EULAR/ACR classification criteria, the sensitivity to diagnose an IIM was 99.6% (95% CI 97.2, 100) and 80.9% (95% CI 76.0, 85.8) for the criteria cut-points of probable and definite diagnoses, respectively. In 94/255 cases the IIM subtype differed between consensus expert opinion and classification criteria, most strikingly in the group subtyped as PM by the EULAR/ACR criteria, where there was discrepancy in the majority (i.e. in 87/161).ConclusionThe EULAR/ACR criteria performed with high sensitivity in identifying IIM in this external cohort of incident IIM. However, substantial disagreements arose between consensus expert opinion and the criteria regarding IIM subtype assignments, resulting in a large proportion of criteria-assigned cases of PM having heterogeneous features. These results may have important implications for future use of these criteria in subsequent research.

Myositis Mimics—a Clinical Approach to a Diagnostic Challenge

Idiopathic inflammatory myopathies (IIMs) encompass a heterogeneous group of disorders generally referred to as myositis. Myositis mimics are common and their overlapping features with IIMs can pose a diagnostic challenge. This review highlights the current knowledge of various myositis mimics, analyzes key distinguishing features from IIMs, and summarizes practical tips in assessing a patient with possible myositis. A new classification criteria for IIMs has been proposed by the European League against Rheumatism/American College of Rheumatology in 2017. Advances in medical genetics have expanded the spectrum of hereditary myopathies, and effective treatment has become available for some. Magnetic resonance imaging (MRI), although not without limitations, is more widely used to differentiate myositis mimics from IIMs. In the end, one must consider the clinical gestalt in formulating a diagnosis. A good clinical history, examination, and judicious use and interpretation of ancillary tests are key in approaching a patient with possible IIMs. Monitoring treatment response is also paramount, not only as a clue to reconsidering the diagnosis but also to prevent unwanted side effects and symptom exacerbation from steroids.

Applicability of EULAR/ACR classification criteria for dermatomyositis to amyopathic disease.

Existing classification systems for idiopathic inflammatory myopathies (IIMs) fail to permit classification and/or diagnosis of amyopathic dermatomyositis (ADM) in patients. In light of the new European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria for IIM, we evaluated the likelihood of the skin variables included in the EULAR/ACR criteria (Gottron's sign, Gottron's papules, and heliotrope rash) to give a high probability of classifying patients with ADM. This retrospective study evaluated 211 adult patients with dermatomyositis at the University of Pennsylvania. The EULAR/ACR criteria were used to determine the probability of classification for patients with ADM. Of patients with ADM, 73.7% would be classified as having a reasonable probability of dermatomyositis on the new EULAR/ACR criteria and 26.3% would not meet the suggested 55% minimum probability cutoff to be classified as having it on the basis of the EULAR/ACR criteria. This study was conducted with a retrospective design at a tertiary academic medical center. The 3 skin variables included in the EULAR/ACR classification criteria for IIM improve on previous criteria but miss classifying some patients with ADM. It is important to consider additional variables such as skin biopsy results to encompass more of these patients and prevent the inclusion of any skin diseases mimicking ADM.

Biologics for idiopathic inflammatory myopathies.

As treatment of refractory cases of idiopathic inflammatory myopathies (IIMs) has been challenging, there is growing interest in assessing novel biologics that target various pathways implicated in the pathogenesis of IIM. In the largest clinical trial in adult and juvenile IIM assessing the effectiveness of rituximab, the primary outcome was not met but 83% of this refractory group of IIM patients met a predefined definition of improvement and rituximab demonstrated a significant glucocorticoid-sparing effect. Antitumor necrosis factor utility in IIM is generally limited by uncertain efficacy data along with recent reports suggesting their potential for inducing systemic autoimmune disease including IIM. Further research is required to evaluate the role of newer therapies such as tocilizumab (anti-interleukin-6), abatacept (inhibition of T-cell costimulation), sifalimumab (anti-interferonα) and ruxolitinib, (Janus kinase inhibitor) given their biological plausibility and encouraging recent small case series results. Future clinical trials should consider the targeting of biomarkers implicated in the etiopathogenesis of IIM, predictive factors of treatment response, recent revisions in IIM classification criteria, as well as newly developed data-driven response criteria which employ validated core set measures.

2017 European League Against Rheumatism/American College of Rheumatology Classification Criteria for Adult and Juvenile Idiopathic Inflammatory Myopathies and Their Major Subgroups.

To develop and validate new classification criteria for adult and juvenile idiopathic inflammatory myopathies (IIM) and their major subgroups. Candidate variables were assembled from published criteria and expert opinion using consensus methodology. Data were collected from 47 rheumatology, dermatology, neurology, and pediatric clinics worldwide. Several statistical methods were utilized to derive the classification criteria. Based on data from 976 IIM patients (74% adults; 26% children) and 624 non-IIM patients with mimicking conditions (82% adults; 18% children), new criteria were derived. Each item is assigned a weighted score. The total score corresponds to a probability of having IIM. Subclassification is performed using a classification tree. A probability cutoff of 55%, corresponding to a score of 5.5 (6.7 with muscle biopsy) "probable IIM," had best sensitivity/specificity (87%/82% without biopsies, 93%/88% with biopsies) and is recommended as a minimum to classify a patient as having IIM. A probability of ≥90%, corresponding to a score of ≥7.5 (≥8.7 with muscle biopsy), corresponds to "definite IIM." A probability of <50%, corresponding toa score of <5.3 (<6.5 with muscle biopsy), rules out IIM, leaving a probability of ≥50-<55% as "possible IIM." The European League Against Rheumatism/American College of Rheumatology (EULAR/ACR) classification criteria for IIM have been endorsed by international rheumatology, dermatology, neurology, and pediatric groups. They employ easily accessible and operationally defined elements, and have been partially validated. They allow classification of "definite," "probable," and "possible" IIM, in addition to the major subgroups of IIM, including juvenile IIM. They generally perform better than existing criteria.

Idiopathic Inflammatory Myopathies; Association with Overlap Myositis and Syndromes: Classification, Clinical Characteristics, and Associated Autoantibodies

Idiopathic inflammatory myopathies (IIM) are traditionally identified as a group of disorders that target skeletal muscle due to autoimmune dysfunction. The IIM can be divided into subtypes based on certain clinical characteristics, and several classification schemes have been proposed. The predominant diagnostic criteria for IIM is the Bohan and Peter criteria, which subdivides IIM into primary polymyositis (PM), primary dermatomyositis (DM), myositis with another connective tissue disease, and myositis associated with cancer. However, this measure has been criticised for several reasons including lack of specific criteria to help distinguish between muscle biopsy findings of PM, DM, and immune-mediated necrotising myopathy, as well as the lack of identification of cases of overlap myositis (OM). Because of this issue, other classification criteria for IIM have been proposed, which include utilising myositis-associated antibodies and myositis-specific antibodies, as well as overlap features such as Raynaud’s phenomenon, polyarthritis, oesophageal abnormalities, interstitial lung disease, small bowel abnormalities such as hypomotility and malabsorption, and renal crises, amongst others. Indeed, the identification of autoantibodies associated with certain clinical phenotypes of myositis, in particular connective tissue disease-myositis overlap, has further helped divide IIM into distinct clinical subsets, which include OM and overlap syndromes (OS). This paper reviews the concepts of OM and OS as they pertain to IIM, including definitions in the literature, clinical characteristics, and overlap autoantibodies.

Diagnosis and classification of idiopathic inflammatory myopathies.

The idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of diseases, collectively termed myositis, sharing symptoms of muscle weakness, fatigue and inflammation. Other organs are frequently involved, supporting the notion that these are systemic inflammatory diseases. The IIMs can be subgrouped into dermatomyositis, polymyositis and inclusion body myositis. The myositis-specific autoantibodies (MSAs) identify other and often more distinct clinical phenotypes, such as the antisynthetase syndrome with antisynthetase autoantibodies and frequent interstitial lung disease and anti-SRP and anti-HMGCR autoantibodies that identify necrotizing myopathy. The MSAs are important both to support myositis diagnosis and to identify subgroups with different patterns of extramuscular organ involvement such as interstitial lung disease. Another cornerstone in the diagnostic procedure is muscle biopsy to identify inflammation and to exclude noninflammatory myopathies. Treatment effect and prognosis vary by subgroup. To develop new and better therapies, validated classification criteria that identify distinct subgroups of myositis are critical. The lack of such criteria was the main rationale for the development of new classification criteria for IIMs, which are summarized in this review; the historical background regarding previous diagnostic and classification criteria is also reviewed. As the IIMs are rare diseases with a prevalence of 10 in 100000 individuals, an international collaboration was essential, as was the interdisciplinary effort including experts in adult and paediatric rheumatology, neurology, dermatology and epidemiology. The new criteria have been developed based on data from more than 1500 patients from 47 centres worldwide and are based on clinically easily available variables.

Diagnostic criteria for idiopathic inflammatory myopathies. Problems of their optimization

The paper deals with the problems of optimizing the diagnostic criteria for idiopathic inflammatory myopathies (IIM), a group of heterogeneous rare autoimmune diseases characterized by inflammatory lesion in the skeletal muscles. The representatives of this group are traditionally considered to be polymyositis (PM), dermatomyositis (DM), and inclusion-body myositis. The authors detail the history of classification criteria for IIM from those proposed by T.A. Medsger et al. (1970) relying on its clinical picture, laboratory data and instrumental findings, as well as the criteria (including the first introduced exclusion ones) elaborated by A. Bohan and J.B. Peter in 1975, which remain fundamental in both clinical practice and researches. The basis for the clinical and serological criteria proposed by Y. Troyanov et al. (2005) for IIM is the identification of myositis-overlap syndromes. The classificational (subtype identification) and therapeutic value of the criteria based on clinical and serological characteristics was supported by the Hungarian investigators A. Vancsa et al. (2010) who investigated the relationship between the clinical and therapeutic characteristics of IIM and positivity for myositis-specific and myositis-associated antibodies. The criteria developed by M.C. Dalakas (1991, 2003) are based on the specific immunopathological features of a histological pattern, which allow the differentiation of DM, PM, and inclusion-body myositis from other myopathic syndromes. The 2004 European Neuromuscular Center (ENMC) criteria first identify necrotizing autoimmune myopathy and nonspecific myositis as individual subtypes. The serological classification of IIM, which is based on the assessment of autoantibodies that play an important role in the pathogenesis of the disease, is of indubitable interest. There is an obvious need for the correct and timely diagnosis of both IIM as a whole and its subtypes in particular, which is complicated by the heterogeneity of the latter. The proposed approaches to diagnosing and classifying IIM have their advantages and disadvantages so that work in this direction is yet to be under way.

THU0241 Ethnic but not gender differences in disease manifestations in dermatomyositis patients

BackgroundDermatomyositis (DM) is a subset of idiopathic inflammatory myopathies (IIM), which are heterogeneous rheumatic disorders characterized by inflammation of skeletal muscle and progressive weakness. New and improved treatment is needed...