Idiopathic Inflammatory Myopathies Cases Research Articles

Assessing PET/CT's diagnostic accuracy in idiopathic myopathies.

Recent studies have utilized fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) specifically to diagnose cases of idiopathic inflammatory myopathies (IIM), excluding inclusion body myositis (IBM). Conversely, carbon-11 (11C) labeled Pittsburgh compound B (PIB)-PET imaging is exclusively used for the detection of IBM. This research is designed to evaluate the diagnostic accuracy of PET/CT in identifying IIM by employing rigorous diagnostic accuracy testing methodologies. A systematic review and meta-analysis were conducted across multiple databases including PubMed, and Embase. We focused on the diagnostic utility of PET/CT in IIM, assessing sensitivities, specificities, and deriving likelihood ratios (LR+ and LR-). The study was registered with PROSPERO (CRD42022343222). This systematic review identified 635 citations, of which 10 eligible trials were included, with a total of 419 participants. The results indicated a sensitivity of 0.86 (0.81-0.90), and a specificity of 0.93 (0.88-0.96). The synthesis of LR revealed the LR+ of 10.35 (6.31-16.98), and LR-of 0.15 (0.07-0.32). The summary receiver operating characteristic curve (SROC) showed an area under the curve (AUC) of 0.9658. Regarding IBM, the sensitivity was 0.84 (0.60-0.97), and the specificity was 1 (0.69-1). The synthesis of LR showed the LR+ of 9.61 (1.46-63.15) and an LR- of 0.21 (0.09-0.51). For disease activity, the sensitivity was 0.96 (0.92-0.99), and the specificity was 0.91 (0.084-0.96). The synthesis of LR showed an LR+ of 9.43 (5.39-16.51) and an LR- of 0.05 (0.02-0.11). Positron emission tomography/CT has great potential for accurately diagnosing and monitoring patients with IIM, and may have implications for their clinical management.

Clinicopathological Reclassification of Idiopathic Inflammatory Myopathy to Match the Serological Results of Myositis-Specific Antibodies.

Advances in serological tests are transforming the classification of idiopathic inflammatory myopathy (IIM). The new criteria suggested by the 119th European Neuromuscular Center international workshop divide IIM cases into four main diseases according to clinical and pathological findings, adding immune-mediated necrotizing myositis and nonspecific myositis to the classic categories of polymyositis and dermatomyositis. Seventy one cases of IIM with sufficient available clinical and pathological data were reviewed to be reclassified according to the new criteria. Most of the cases previously classified as polymyositis (77.8%, 35/45) were reclassified as immune-mediated necrotizing myopathy. The results of myositis-specific antibodies matched well with the new clinicopathological classification. This new clinicopathological classification for IIM in combination with serological test results could be applied to our previous case series. Adoption of the new criteria will lead to a better understanding of the disease and hence new therapeutic insights.

Impact of SARS-CoV-2 on the clinical presentation of juvenile idiopathic inflammatory myopathies

BackgroundGrowing evidence suggests that infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may trigger idiopathic inflammatory myopathies (IIM). Few studies have described individual juvenile IIM (JIIM) cases following SARS-CoV-2 infection, and none explored its potential effects on JIIM clinical presentation. We aim to investigate the impact of SARS-CoV-2 on JIIM in patients diagnosed before and after the onset of the Coronavirus Disease 2019 (COVID-19) pandemic.MethodsPatients diagnosed with JIIM before age 19 at The Children’s Hospital at Montefiore were included. Demographics, clinical and laboratory data, and evidence of SARS-CoV-2 exposure were collected retrospectively. Patients were grouped by pre-COVID-19 (before January 1, 2020) and post-COVID-19 (January 1, 2020, or later). Descriptive statistics were used to summarize each variable. Non-parametric testing was performed using Fischer’s exact test and Mann-Whitney U test.ResultsFifty-one patients were included, 13 (25%) diagnosed in the post-COVID-19 era. Of these, 10 (77%) had onset of JIIM symptoms after January 1, 2020; 6 (60%) with known or suspected SARS-CoV-2 exposure. Though not statistically significant, post-pandemic patients tended to be older, female, and have non-specific cutaneous manifestations. Despite reported delays in care for other pediatric diagnoses during the pandemic, fewer post-pandemic patients had delays in JIIM diagnosis.ConclusionsThis is the first study to explore the effects of SARS-CoV-2 on JIIM clinical presentation. While our exploratory single-center study did not find significant differences in JIIM diagnosed pre- and post-pandemic, larger prospective multicenter studies are warranted to evaluate this association and to explore clinical variances over time.

18F]FDG-PET/CT in Idiopathic Inflammatory Myopathies: Retrospective Data from a Belgian Cohort.

[18F]FDG-PET/CT is a useful tool for diagnosis and cancer detection in idiopathic inflammatory myopathies (IIMs), especially polymyositis (PM) and dermatomyositis (DM). Data deriving from Europe are lacking. We describe [18F]FDG-PET/CT results in a Belgian cohort with IIMs, focusing on patients with PM and DM. All of the cases of IIMs admitted between December 2010 and January 2023 to the Cliniques Universitaires Saint-Luc (Belgium) were retrospectively reviewed. In total, 44 patients were identified with suspected IIMs; among them, 29 were retained for final analysis. The mean age of the retained patients was 48.7 years; 19 patients were female (65.5%). Twenty-two patients had DM and seven had PM. The mean serum creatinine kinase (CK) and the mean CRP levels were 3125 UI/L and 30.3 mg/L, respectively. [18F]FDG-PET/CT imaging was performed for 27 patients, detecting interstitial lung diseases (ILDs) in 7 patients (25.9%), cancer in 3 patients (11.1%), and abnormal muscle FDG uptake compatible with myositis in 13 patients (48.1%). All of the patients who were detected to have ILDs via PET/CT imaging were confirmed using a low-dose lung CT scan. Among the patients who were detected to have abnormal muscle FDG uptake via PET/CT scans (13/28), the EMG was positive in 12 patients (p = 0.004), while the MRI was positive in 8 patients (p = 0.02). We further observed that there was a significantly higher level of CK in the group with abnormal muscle FDG uptake (p = 0.008). Our study showed that PET/CT is useful for detecting cancer and ILDs. We showed that the detection of abnormal muscle uptake via PET/CT was in accordance with EMG and MRI results, as well as with the mean CK value, and that the presence of dyspnea was significantly associated with the presence of ILDs detected via PET/CT imaging (p = 0.002).

Comparison of Muscle Biopsy Features with Myositis Autoantibodies in Inflammatory Myopathies: A Pilot Experience

Abstract Background: Idiopathic inflammatory myopathies (IIM), also called autoimmune myositis, are heterogeneous. These include dermatomyositis (DM), inclusion body myositis, immune mediated necrotizing myopathy (IMNM), anti-synthetase syndrome (ASS), and overlap polymyositis. Classification of IIM has evolved from clinical to clinico-pathologic to the recent clinico-sero-pathologic with the discovery of myositis-specific antibodies (MSA) and myositis-associated antibodies. The various antibodies have shown association with specific phenotypes. Objective: To analyze muscle biopsy features with respect to each MSA and MAA to understand the frequency of findings in each entity. Materials and Methods: Biopsy-proven cases of IIM where myositis profile was available were included in the study after obtaining Institutional Ethics Committee (IEC) approval. In addition to the stains and enzyme histochemistry, immunohistochemistry with MHC class I and II and MxA was performed. Features like perifascicular atrophy, perifascicular necrosis, scattered necrosis, inflammation, etc. were analyzed. Myositis profile was performed by line-blot technique using a 16-antigen panel. Cases were divided into different autoantibody subgroups. Various clinical, demographic, and muscle biopsy features were studied with respect to each MSA and MAA. Results: There were a total of 64 cases. Mi2 (N = 18) was the most common autoantibody. Some of the salient observations included PFA with perivascular inflammation in Mi2; pediatric cases and microinfarcts in NXP2; no PFA or inflammation in MDA5; perifascicular necrosis in JO1; extensive necrosis with sparse inflammation in SRP; more inflammation in overlap myositis; MxA positivity in DM; and absent in ASS. Conclusion: This is a pilot study documenting differences in biopsy phenotype with each MSA and MAA which is comparable to the literature. These findings can be used to characterize IIM in seronegative biopsies.

Validation of methods to identify people with idiopathic inflammatory myopathies using hospital episode statistics.

Hospital episode statistics (HES) are routinely recorded at every hospital admission within the National Health Service (NHS) in England. This study validates diagnostic ICD-10 codes within HES as a method of identifying cases of idiopathic inflammatory myopathies (IIMs). All inpatient admissions at one NHS Trust between 2010 and 2020 with relevant diagnostic ICD-10 codes were extracted from HES. Hospital databases were used to identify all outpatients with IIM, and electronic care records were reviewed to confirm coding accuracy. Total hospital admissions were calculated from NHS Digital reports. The sensitivity and specificity of each code and code combinations were calculated to develop an optimal algorithm. The optimal algorithm was tested in a sample of admissions at another NHS Trust. Of the 672 individuals identified by HES, 510 were confirmed to have IIM. Overall, the positive predictive value (PPV) was 76% and sensitivity 89%. Combination algorithms achieved PPVs between 89 and 94%. HES can also predict the presence of IIM-associated interstitial lung disease (ILD) with a PPV of 79% and sensitivity of 71%. The optimal algorithm excluded children (except JDM code M33.0), combined M33.0, M33.1, M33.9, M36.0, G72.4, M60.8 and M33.2, and included M60.9 only if it occurred alongside an ILD code (J84.1, J84.9 or J99.1). This produced a PPV of 88.9% and sensitivity of 84.2%. Retesting this algorithm at another NHS Trust confirmed a high PPV (94.4%). IIM ICD-10 code combinations in HES have high PPVs and sensitivities. Algorithms tested in this study could be applied across all NHS Trusts to enable robust and cost-effective whole-population research into the epidemiology of IIM.

COVID-19 Vaccination in Autoimmune Diseases (COVAD) study: Vaccine safety in idiopathic inflammatory myopathies.

Introduction/AimsIn this study we investigated COVID‐19 vaccination–related adverse events (ADEs) 7 days postvaccination in patients with idiopathic inflammatory myopathies (IIMs) and other systemic autoimmune and inflammatory disorders (SAIDs).MethodsSeven‐day vaccine ADEs were collected in an international patient self‐reported e‐survey. Descriptive statistics were obtained and multivariable regression was performed.ResultsTen thousand nine hundred respondents were analyzed (1227 IIM cases, 4640 SAID cases, and 5033 healthy controls [HCs]; median age, 42 [interquartile range, 30‐455] years; 74% female; 45% Caucasian; 69% completely vaccinated). Major ADEs were reported by 76.3% of the IIM patients and 4.6% reported major ADEs. Patients with active IIMs reported more frequent major (odds ratio [OR], 2.7; interquartile range [IQR], 1.04‐7.3) and minor (OR, 1.5; IQR, 1.1‐2.2) ADEs than patients with inactive IIMs. Rashes were more frequent in IIMs (OR, 2.3; IQR, 1.2‐4.2) than HCs. ADEs were not impacted by steroid dose, although hydroxychloroquine and intravenous/subcutaneous immunoglobulins were associated with a higher risk of minor ADEs (OR, 1.9; IQR, 1.1‐3.3; and OR, 2.2; IQR, 1.1‐4.3, respectively). Overall, ADEs were less frequent in inclusion‐body myositis (IBM) and BNT162b2 (Pfizer) vaccine recipients.DiscussionSeven‐day postvaccination ADEs were comparable in patients with IIMs, SAIDs, and HCs, except for a higher risk of rash in IIMs. Patients with dermatomyositis with active disease may be at higher risk, and IBM patients may be at lower risk of specific ADEs. Overall, the benefit of preventing severe COVID‐19 through vaccination likely outweighs the risk of vaccine‐related ADEs. Our results may inform future guidelines regarding COVID‐19 vaccination in patients with SAIDs, specifically in those with IIMs. Studies to evaluate long‐term outcomes and disease flares are needed to shed more light on developing future COVID‐19 vaccination guidelines.

Clinical and pathological features of immune-mediated necrotising myopathies in a single-centre muscle biopsy cohort.

ObjectiveImmune-mediated necrotising myopathy (IMNM) is a subset of idiopathic inflammatory myopathies (IIM) characterized by significantly elevated creatine kinase level, muscle weakness and predominant muscle fibre necrosis in muscle biopsy. This study aimed to investigate the clinical and pathological characteristics of patients with IMNM in a single-centre muscle biopsy cohort.MethodsA total of 860 patients who had muscle biopsy reports in our centre from May 2008 to December 2017 were enrolled in this study. IMNM was diagnosed according to the 2018 European Neuromuscular Centre (ENMC) clinicopathological diagnostic criteria for IMNM.ResultsThe muscle biopsy cohort consisted of 531 patients with IIM (61.7%), 253 patients with non-IIM (29.4%), and 76 undiagnosed patients (8.8%). IIM cases were classified as IMNM (68[7.9%]), dermatomyositis (346[40.2%]), anti-synthetase syndrome (82[9.5%]), polymyositis (32[3.7%]), and sporadic inclusion body myositis (3[0.3%]). Limb girdle muscular dystrophy (LGMD) 2B and lipid storage myopathy (LSM) are the two most common non-IIM disorders in our muscle biopsy cohort. IMNM patients had a higher onset age (41.57 ± 14.45 vs 21.66 ± 7.86 and 24.56 ± 10.78, p < .0001), shorter duration (21.79 ± 26.01 vs 66.69 ± 67.67 and 24.56 ± 10.78, p < .0001), and more frequent dysphagia (35.3% vs. 3.4 and 6.3%, p = .001) than LGMD 2B and LSM patients. Muscle biopsy from IMNM showed more frequent muscle fibre necrosis (95.6% vs 72.4 and 56.3%, p < .0001), overexpression of major histocompatibility complex-I on sarcolemma (83.8% vs 37.9 and 12.9%, p < .0001), and CD4+ T cell endomysia infiltration (89.7% vs 53.6 and 50%, p < .0001) compared with those from LGMD 2B and LSM patients.ConclusionsIt is easy to distinguish IMNM from other IIM subtypes according to clinical symptoms and myositis specific antibodies profiles. However, distinguishing IMNM from disorders clinically similar to non-IIM needs combined clinical, serological and pathological features.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12891-022-05372-z.

The Geospatial Distribution of Myositis and Its Phenotypes in the United States and Associations With Roadways: Findings From a National Myositis Patient Registry.

BackgroundLittle is known about the spatial distribution of idiopathic inflammatory myopathies (IIM) in the United States (U.S.), or their geospatial associations.MethodsWe studied a national myositis patient registry, with cases diagnosed in the contiguous U.S. from 1985–2011 and comprised of dermatomyositis (DM, n = 484), polymyositis (PM, n = 358), and inclusion body myositis (IBM, n = 318) patients. To assess the association of myositis prevalence with distance from roads, we employed log-Gaussian Cox process models, offset with population density.ResultsThe U.S. IIM case distribution demonstrated a higher concentration in the Northest. DM, IBM, and cases with lung disease were more common in the East, whereas PM cases were more common in the Southeast. One area in the West and one area in the South had a significant excess in cases of DM relative to PM and of cases with lung disease relative to those without lung disease, respectively. IIM cases tended to cluster, with between-points interactions more intense in the Northeast and less in the South. There was a trend of a higher prevalence of IIM and its major phenotypes among people living within 50 m of a roadway relative to living beyond 200 m. Demographic characteristics, rural-urban commuting area, and female percentage were significantly associated with the prevalence of IIM and with major phenotypes.ConclusionsUsing a large U.S. database to evaluate the spatial distribution of IIM and its phenotypes, this study suggests clustering in some regions of the U.S. and a possible association of proximity to roadways.

The risk of ischemic stroke in patients with idiopathic inflammatory myopathies: a systematic review and meta-analysis.

Idiopathic inflammatory myopathies (IIM) are a group of chronic rheumatic diseases that can affect multiple systems; the risk of ischemic stroke in patients with IIM remains controversial. We aimed to systematically evaluate the risk of ischemic stroke in IIMs. The PubMed, Embase, and Cochrane library were searched for relevant studies. Pooled relative risk (RR) with a 95% confidence interval (CI) was calculated as effect size to evaluate the risk of ischemic stroke in patients with IIM. Random effects model was chosen when I2 > 50%. We pooled all studies in a first total analysis to assess the risk of ischemic stroke in IIM. Subgroup analyses were conducted based on the subtypes of IIM (dermatomyositis) and country. Sensitivity analysis was performed to identify the heterogeneity sources. A total of 6 studies with 5,114 IIM cases and 14,516,099 controls were included, and the results demonstrated that IIMs were associated with an increased risk of ischemic stroke (RR = 2.41, 95% CI: 1.31, 4.45). Subgroup analysis indicated that patients with dermatomyositis (DM) had a 49% excess risk of ischemic stroke than controls; Asian patients with IIM had an increased risk of ischemic stroke, although not for American patients. IIMs, especially patients with DM, are associated with an increased risk of ischemic stroke. Appropriate intervention may be taken into account for patients with IIM, especially when accompanied by other traditional risk factors of ischemic stroke. Key Points • This study evaluated the risk of ischemic stroke in patients with IIMs. • Generally, IIMs are associated with an increased risk of ischemic stroke. • Patients with DM had a 49% excess risk of ischemic stroke than controls. • Subgroup analysis showed that Asian patients with IIMs were at increased risk of ischemic stroke, but not Americans.

P090 Validation of hospital episode statistics data to enable national registration of idiopathic inflammatory myopathies

Abstract Background/Aims The National Congenital Anomaly and Rare Disease Registration Service (NCARDRS) aims to register all patients in England with congenital or rare diseases. Maintaining ongoing contemporaneous registers requires substantial time and resource, so novel methodologies for identification and registration of rare disorders such as the idiopathic inflammatory myopathies (IIMs) need development. Hospital Episode Statistics (HES) are routinely recorded data from every hospital admission within the National Health Service (NHS) England. This study aims to validate diagnostic ICD-10 codes within HES as a method of identifying and recording cases of IIM. Methods In collaboration with the Registration of Complex Rare Diseases - Exemplars in Rheumatology (RECORDER) project we extracted all Finished Consultant Episodes (FCE) at one hospital trust between 2010-2019 with diagnostic ICD-10 codes indicating either dermatomyositis or polymyositis under NCARDRS section 251 legal permissions (CAG 10-02(d)/2015). Co-occurring interstitial lung disease (ILD) was also considered due to ILDs association with IIMs. Hospital rheumatology and immunology databases were interrogated to identify all outpatients with IIM. Hospital electronic care records were reviewed to confirm coding accuracy. The total number of FCEs at the trust was calculated from NHS Digital reports. Sensitivity and specificity of each code and various code combination algorithms were calculated. Results HES ICD-10 codes identified 530 individuals, of whom 388 had records confirming IIM diagnosis. 146 additional patients were found through hospital records. This gives these codes a positive predictive value (PPV) of 73.1% and sensitivity of 72.7%. Due to the rarity of IIM coded FCEs compared to all FCEs, the specificity is 100.0% for every code. Dermatomyositis codes M331 and M339 had PPV 94.8% and 93.4% respectively. Juvenile DM (M330) and paraneoplastic myositis (M360) whilst rarely used had a high PPV of 91.6% and 100% respectively. Myositis unspecified (M609), was the worst performing code with PPV 61.4%. Excluding M609 from the analysis, PPV improved to 85.9%. Adding an ILD code made specificity 94.2% and sensitivity 15.5%, however it did find 51.5% of the known IIM-ILD patients. Strategies to improve PPV without impacting sensitivity were attempted. The highest PPV of 95.3% was found by selecting patients who had at least 2 different codes recorded, however sensitivity was only 30.7%. By then adding patients who also had one of the high performing codes the PPV dropped to 91.73% but sensitivity improved to 60.7%. Conclusion This is the first validation cohort to show that IIM ICD code combinations in HES have high positive predictive values, and sensitivities of up to 72.7%. The relative importance of sensitivity, specificity and PPV vary according to the research question being asked, but algorithms tested in this study could be applied across all NHS trusts to enable robust and cost-effective whole-population research into the epidemiology of IIM. Disclosure J.R. Hannah: None. P. Gordon: None. J. Galloway: None. E.J. Peach: Grants/research support; Vifor Pharma. P.C. Lanyon: Grants/research support; Vifor Pharma. M. Bythell: None. F.A. Pearce: Grants/research support; Vifor Pharma.

Epidemiology of Idiopathic Inflammatory Myopathies in Africa: A Contemporary Systematic Review.

The epidemiology of idiopathic inflammatory myopathies (IIMs) has been extensively studied in America, Europe, and Asia, but remains unclear in Africa. The aim of this review was to summarize available data on the epidemiology of IIMs in Africa. We searched MEDLINE, EMBASE, and African Journals Online for studies published up to December 30, 2020, and reporting epidemiological data on IIMs in Africa. Data were combined through narrative synthesis. The review protocol was registered with PROSPERO, CRD42020186781. We included 39 studies reporting 683 cases (71.7% adults) of IIMs. Incidence rates of ~7.5/1,000,000 person-years and 1.2/1,000,000 person-years were estimated for dermatomyositis (DM), whereas polymyositis (PM) had an incidence rate of 8.8/1,000,000 person-years. Prevalence estimates of 11.49/100,000 and 11/100,000 (95% confidence interval, 0-32) were provided for IIMs and the PM subtype, respectively. Mean age at diagnosis ranged from 7.9 to 57.2 years, and 50% to 100% of the patients were females. Main subtypes of adult-onset IIMs were DM (21%-93%) and PM (12%-79%), whereas the commonest juvenile subtype was juvenile DM (5.8%-9%). Skeletal muscle involvement (56%-100%) was the main disease feature, and esophagus was the most commonly affected internal organ (6%-65.2%). Anti-Jo1/histidyl tRNA synthetase (7%-100%) and anti-Mi2 (17%-45%) antibodies were the most frequent myositis specific antibodies. Early mortality was high (7.8%-45%), and main death causes were infections, cancers and organ damage in respiratory and cardiovascular domains. Apart from a potential younger age at onset of adult IIMs in Africa, current sparse data mostly suggest a similar epidemiology between Africa and other regions. Further high-quality studies are required to validate these findings.

Edematous myositis: a clinical presentation first suggesting dermatomyositis diagnosis.

Edema of the limbs is uncommon in idiopathic inflammatory myopathies (IIM). The few reported cases have been associated with severe and refractory dermatomyositis (DM), sometimes in association with cancers. We aimed to determine if edematous myositis is a homogeneous subtype based on clinical, serological and pathological features. This is a retrospective observational study performed between 2008 and 2015 in the French national referral center for myositis. All adult patients with an inflammatory muscle biopsy and upper limbs edema were included as well as IIM cases without limb edema as controls. Clinical, biological and pathological features were collected. Seventeen edematous myositis were included and compared to 174 IIM without edema, including 50 DM controls. Edema was the first manifestation in 23% of patients. Muscle weakness was severe and symmetric, 71% of patients presented dysphagia and a restrictive ventilatory pattern was found in 40%. Fifty-two percent of patients had a typical DM skin rash and 23% had cancer within 3years of diagnosing myositis. Fifty-three percent of patients presented a myositis specific antibody and only DM-specific antibodies were detected. Classic pathological DM features (perifascicular atrophy, perifascicular/perimysial perivascular inflammation) were uncommon but capillary C5b-9 deposition and MxA expression were seen in 79% and 73% of cases, respectively. A perimysial edema was found in 82% of cases. Seventeen percent of patients died (median follow up of 18months). Edematous myositis demonstrated more marked capillary C5b-9 deposition compared to IIM controls. There was no clinical, biological or pathological difference with DM controls except for limb edema. Our study underlines that limb edema could be a symptom of IIM and that edematous myositis are mostly DM. The vasculopathy seems to play a key role in its pathophysiology. Limb edema associated with muscle impairment should suggest the diagnosis of DM in clinical settings.

Temporal relationship between idiopathic inflammatory myopathies and malignancies and its mortality: a nationwide population-based study.

To examine the temporal relationship between malignancies and idiopathic inflammatory myopathies (IIMs) and its impact on mortality. A retrospective cohort for IIM patients was conducted using the Korean National Health Insurance Service databases. We observed more than 5years before and after the diagnosis of IIM (2002~2016) to identify IIM patients who developed any malignancy and classified these patients into two groups: the cancer-associated myositis (CAM) group, who developed malignancy within 3years before or after the diagnosis of IIM and the cancer-not-associated myositis (CNAM) group, who developed malignancy beyond 3years of IIM onset. The survival rates of the two groups were compared. We identified 1072 incident cases of IIM between 2007 and 2011. A total 225 patients of these patients were diagnosed with malignancy. The development of malignancy was frequent within 1year before and after the time of IIM diagnosis. The common sites of malignancies in the CAM group differed from those in the CNAM group: the lung, hematologic malignancy, and the liver were common in both groups, but thyroid and oropharynx followed them in CAM while prostate, stomach, breast, and thyroid followed them in CNAM. CAM patient mortality was worse compared with CNAM patients (log-rank test, p < 0.01). Among IIM patients with malignancy, common sites of malignancy were different between the CAM and CNAM groups, and patients with CAM had poor prognosis compared with CNAM patients. Key Points • The malignancies commonly occurred in incident idiopathic inflammatory myopathy (IIM) patients, especially within 1year before and after the initial IIM diagnosis. • Patients with malignancy had poor survival compared with patients without malignancy. • Among the IIM patients with malignancy, patients who developed malignancy within 3years of IIM diagnosis (cancer-associated myositis, or CAM, group) showed higher mortality than cancer-not-associated myositis, CNAM group. • We also found that the common types of malignancy were different between the CAM and CNAM groups.

O33 Earlier cancer diagnosis after myositis onset is associated with improved long term survival: results from UK, French and Czech cohorts

Abstract Background The idiopathic inflammatory myopathies (IIMs) are associated with cancer. Cancer screening is advocated in new IIM cases; however no study has investigated if this confers improved long-term survival. This study aimed to investigate if a shorter time between IIM onset and cancer diagnosis is associated with improved survival. Methods Verified adult-onset IIM (dermatomyositis, polymyositis, anti-synthetase syndrome) cases, according to the International Myositis Classification Criteria, were recruited from three separate UK (UKMYONET), France and Czech-based cohort studies. Only cases with cancer diagnosis following IIM onset were included in analysis. The time between IIM onset and cancer diagnosis was calculated for each case. The relationship between survival at the end of follow up and time between IIM onset and cancer diagnosis was quantified via calculation of hazard ratios using a Cox-proportional hazard model, adjusted for age and gender. Results A total of 193 (66% female) IIM cases with a total of 1,395 person-years follow up were included in the analysis (Table 1). Data of 120 UK, 45 Czech and 28 French participants were analysed. Breast was the most common site of cancer (16%), followed by lung (9%) and bowel (6%). Forty six (24%) deaths occurred within the follow up period. The IIM onset to cancer diagnosis time was shorter for those that survived at the end of follow up, compared to those that died: 4.6 years (IQR 1.2, 10.7), vs 5.8 years (IQR 1.6, 13.8), respectively. Cox-proportional hazard modelling, indicated that a longer time between IIM onset and cancer diagnosis was significantly associated with death (HR 1.06 [95% CI 1.02, 1.10]). This significant relationship was only demonstrated in the female cohort when analysed separately: female HR 1.06 (95% CI 1.01, 1.10), male HR 1.08 (95% CI 0.98, 1.18). Conclusion Using data from three international cohorts, this study has, for the first time, identified that earlier cancer diagnosis after IIM onset is associated with improved long term survival. This finding was observed in the female cohort only. This study therefore indicate that cancer screening in newly diagnosed IIM cases without a preceding cancer history should be carried out, especially in female cases. Disclosures A. Oldroyd None. P. New None. J. Lamb None. W. Ollier None. R. Cooper None. K. Mariampillai None. O. Benveniste None. J. Vencovský None. H. Mann None. H. Chinoy None.

The Clinical Heterogenicity and the Diagnostic Challenges of Idiopathic Inflammatory Myopathies

Objective: The idiopathic inflammatory myopathies (IIMs) are a heterogeneous group of disorders. Determining the diagnosis of the specific type of IIM based on the current diagnostic criteria correlate poorly with the clinical course and outcomes. New and more accurate classification criteria are needed. Methods: Five cases of IIM who were followed at the rheumatology division at Galilee Medical Center between 2017 and 2019. The data was retrospectively extracted from the hospital electronical medical record Results: Records of 5 patients diagnosed with IIMs were reviewed including 3 patients diagnosed with Antisynthetase syndrome (AAS) and 2 patients diagnosed with Dermatomyositis (DM) and Polymoysitis (PM) respectively. The clinical presentation of those patients was heterogeneous as well as their response to treatment. Conclusions: The current classification criteria aims to classify the patients into homogenous groups. However, even with the current classification criteria, patients diagnosed within the same subgroup, e.g. AAS, may still have variable clinical presentations and unpredictable response to treatment, emphasizing the unmet need for a better classification criteria.

Performance of the new EULAR/ACR classification criteria for idiopathic inflammatory myopathies (IIM) in a large monocentric IIM cohort

BackgroundIn 2017, the European League Against Rheumatism (EULAR) and the American College of Rheumatology (ACR) published new classification criteria for idiopathic inflammatory myopathies (IIM). ObjectivesTo [1] assess the performance of the EULAR/ACR criteria in a monocentric cohort of consecutive patients with IIM, compare them with the Bohan and Peter (BP) criteria, and with the physician's diagnosis; and [2] evaluate the effect of including the presence of interstitial lung disease (ILD) as variable in the criteria. Methods439 consecutive patients with a diagnosis of IIM followed at the Rheumatology Clinic, Karolinska University Hospital, Sweden were enrolled. The patients were diagnosed as IIM and subclassified by expert physicians. Clinical, laboratory, serological and histopathological data were collected from existing databases (Euromyositis registry and Swedish Rheumatology quality registry) and clinical charts of the patients. The sensitivity of the EULAR/ACR and the BP criteria was calculated. ResultsThe EULAR/ACR criteria had a higher sensitivity (87.7%) compared to the BP criteria (80.4%). The concordance between the two sets of criteria was low (k = 0.253 p<0.001). The EULAR/ACR criteria showed a very high specificity (>98%) for the major IIM subgroups polymyositis, dermatomyositis, and inclusion body myositis. The sensitivity was variable and was high in inclusion body myositis (98%), dermatomyositis (90%) and lower in polymyositis (73%). When including ILD in the variables of the criteria, six more patients were classified as IIM cases (1.3%). ConclusionThe EULAR/ACR criteria for IIM are applicable with high sensitivity and specificity using data available from existing databases and clinical charts and represent a major step forward from the previous criteria for IIM and its subgroups. Their application will improve the quality of clinical trials and research studies with IIM patients.

First external validation of sensitivity and specificity of the European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) classification criteria for idiopathic inflammatory myopathies with a Japanese cohort

ObjectiveTo externally validate the performance of the new European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) classification criteria set for idiopathic inflammatory myopathies (IIM) with a Japanese cohort.MethodsThis study...

A review of accelerometer-derived physical activity in the idiopathic inflammatory myopathies

BackgroundThe idiopathic inflammatory myopathies (IIMs) are a group of rare conditions characterised by muscle inflammation (myositis). Accurate disease activity assessment is vital in both clinical and research settings, however, current available methods lack ability to quantify associated variation of physical activity, an important consequence of myositis.This study aims to review studies that have collected accelerometer-derived physical activity data in IIM populations, and to investigate if these studies identified associations between physical and myositis disease activity.MethodsA narrative review was conducted to identify original articles that have collected accelerometer-derived physical activity data in IIM populations. The following databases were searched from February 2000 until February 2019: Medline via PubMed, Embase via OVID and Scopus.ResultsOf the 297 publications screened, eight studies describing accelerometer use in 181 IIM cases were identified. Seven out of the eight studies investigated juvenile dermatomyositis (JDM) populations and only one reported on an adult-onset population. Population sizes, disease duration, accelerometer devices used, body placement sites, and study duration varied between each study.Accelerometer-derived physical activity levels were reduced in IIM cohorts, compared to healthy controls, and studies reported improvement of physical activity levels following exercise programme interventions, thus demonstrating efficacy.Higher levels of accelerometer-derived physical activity measurements were associated with shorter JDM disease duration, current glucocorticoid use and lower serum creatine kinase. However, no clear association between muscle strength and accelerometer-derived physical activity measures was identified.ConclusionsThe use of accelerometer-derived physical activity in IIM research is in its infancy. Whilst knowledge is currently limited to small studies, the opportunities are promising and future research in this area has the potential to improve disease activity assessment for clinical and research applications.

Incidence and Prevalence of Idiopathic Inflammatory Myopathies in Korea: a Nationwide Population-based Study.

BackgroundThis study aimed to estimate the incidence and prevalence of idiopathic inflammatory myopathies (IIM) and associated comorbidities in Korea from 2006 to 2015.MethodsIIM between 2004 to 2015 were identified using the Korean National Health Insurance Service medical claim database. The case definition required more than one visit based on diagnostic codes including juvenile dermatomyositis (JDM), dermatomyositis (DM), or polymyositis (PM) and registration in the Individual Copayment Beneficiaries Program (ICBP) for rare and intractable diseases. IIM patients with a disease-free period of 24 months before the index date were defined as incident cases. The Elixhauser comorbidity score was calculated.ResultsUsing the base case definition, 1,150 prevalent patients with IIM (117 JDM, 521 DM, 512 PM) were recorded in 2006 and 2,210 (130 JDM, 1,101 DM, 869 PM) in 2015. The prevalence was estimated at 2.3–4.0 (0.9–1.2 for JDM, 1.2–2.7 for DM, 1.4–2.1 for PM)/100,000 person-year (PY). We identified 218 incident cases of IIM in 2006 (18 JDM, 98 DM, 102 PM) and 191 cases (7 JDM, 83 DM, 101 PM) in 2015. The incidence was estimated at 2.9–5.2 (0.7–1.9 for JDM, 1.8–4.0 for DM, 1.6–3.0 for PM)/1,000,000 PY. The mean age (± standard deviation) of prevalent patients with IIM was 51.2 (± 16.9) years, and the percentage of women was 72.1%. More than two-thirds of patients (70.7%) had more than two comorbidities. Twenty percent of patients had interstitial lung diseases.ConclusionIn Korea, the incidence and prevalence of IIM were 2.9–5.2/1,000,000 PY and 2.3–4.0/100,000 PY, respectively.