Incidence and prevalence of idiopathic inflammatory myopathies in Thailand from the Ministry of Public Health data analysis.

The epidemiology of idiopathic inflammatory myopathies (IIMs) varies by country. Investigating the epidemiological profile among Thai IIMs could help to inform public health policy, potentially leading to cost-reducing strategies. We aimed to assess the prevalence and incidence of IIM in the Thai population between 2017 and 2020. A descriptive epidemiological study was conducted on patients 18 or older, using data from the Information and Communication Technology Center, Ministry of Public Health, with a primary diagnosis of dermatopolymyositis, as indicated by the ICD-10 codes M33. The prevalence and incidence of IIMs were analyzed with their 95% confidence intervals (CIs) and then categorized by sex and region. In 2017, the IIM cases numbered 9,074 among 65,204,797 Thais, resulting in a prevalence of 13.9 per 100,000 population (95% CI 13.6-14.2). IIMs were slightly more prevalent among women than men (16.8 vs 10.9 per 100,000). Between 2018 and 2020, the incidence of IIMs slightly declined from 5.09 (95% CI 4.92-5.27) in 2017 and 4.92 (95% CI 4.76-5.10) in 2019 to 4.43 (95% CI 4.27-4.60) per 100,000 person-years in 2020. The peak age group was 50-69 years. Between 2018 and 2020, the majority of cases occurred in southern Thailand, with incidence rates of 7.60, 8.34, and 8.74 per 100,000 person-years. IIMs are uncommon among Thais, with a peak incidence in individuals between 60 and 69, especially in southern Thailand. The incidence of IIMs decreased between 2019 and 2020, most likely due to the COVID-19 pandemic, which reduced reports and investigations.

Association of anti-Ro-52 antibodies with occurrence of interstitial lung disease in patients with idiopathic inflammatory myopathy.

BACKGROUND: Anti-Ro-52 antibodies have been associated with interstitial lung disease (ILD) in various autoimmune diseases. However, their role in ILD among patients with idiopathic inflammatory myopathies (IIMs) is relatively underexplored. This study aimed to investigate the association between anti-Ro-52 antibodies and the occurrence of ILD in individuals with IIMs. METHODS: This retrospective observational study included 604 patients who underwent myositis autoantibody testing between July 2018 and January 2021 at our hospital and were diagnosed with either IIMs or IIM-mimics. Comparative analyses were conducted between IIMs and IIM-mimics, as well as within the IIM group between cases with and without ILD. Logistic regression or Firth's logistic regression analyses were employed to assess the risk of ILD development in different IIM subgroups and myositis antibody categories. RESULTS: This study included 190 patients with IIM and 414 patients with IIM-mimics. Patients with IIM demonstrated higher incidence of ILD, concurrent autoimmune disease, and a greater likelihood of various myositis autoantibodies when compared to the IIM-mimics group. Within the IIM patient cohort, those with ILD exhibited a later age of onset of IIM, an increased mortality rate, and a more frequent presence of anti-aminoacyl-tRNA synthetase (ARS) antibodies compared to those without ILD. The presence of any myositis-specific antibody (MSA) was associated with a six-fold increased risk of ILD, while dual positivity for MSA and anti-Ro-52 antibodies conferred a twenty-fold risk. Anti-ARS antibodies carried a 14-fold increased risk of ILD, which escalated to 38-fold in cases of dual positivity for anti-ARS and anti-Ro-52 antibodies. Anti-Ro-52 antibodies alone increased the risk eight-fold. CONCLUSIONS: Among patients with IIM, the presence of ILD was linked to higher mortality. Certain autoantibodies, notably anti-ARS and anti-Ro-52 antibodies, were associated with an increased risk of ILD. The greatest risk of ILD was observed in cases of dual positivity for anti-ARS and anti-Ro-52 antibodies.

Exploring the link between inflammatory myopathies and cancer: A comprehensive retrospective analysis in a Colombian cohort.

BACKGROUND: This study investigates the association between inflammatory myopathies (IM), and their correlation with cancer. There are several potential causes behind the association of cancer and inflammatory myopathies. The positivity of specific antibodies for myositis plays a significant role. Our objective is to describe cancer and inflammatory myopathies in Colombia, focusing on demographics, clinical characteristics, and laboratory data. METHODS: We retrospectively analyzed 112 IM patients diagnosed at Fundación Valle del Lili in Cali, Colombia, the cases met the EULAR/ACR criteria. Data included demographics, clinical signs, laboratory findings, and malignancy. Malignancy associations were explored using logistic regression. The survival analysis was assessed using Kaplan-Meier curves and the Log-Rank test. RESULTS: Dermatomyositis was the most common subtype (45.5%), with a female predominance (66.1%). Cancer diagnosis occurred in 11.6% of cases, predominantly thyroid cancer. The median time from myopathy onset to cancer diagnosis was 11 months, with 75% of cases within the first year. Bivariate analysis indicated associations between cancer and age, Gottron's papules, digital ulcers, and heliotrope rash. However, multivariate analysis identified age as the only significant malignancy risk factor. Survival analysis showed better rates in younger patients. CONCLUSION: This study provides into the link between IM and cancer in the Colombian population. Thyroid cancer predominated, with a slightly higher proportion of female cancer diagnoses. Age emerged as a significant risk factor for malignancy. Understanding this association is crucial for early detection and improving patient outcomes related to IM-associated malignancies.

Celiac disease prevalence in patients with idiopathic inflammatory myopathies, a cross-sectional study.

Up to 30% of patients with celiac disease (CD) suffer from concurrent autoimmune disease, compared to 3% of the general population. The association between CD and the current clinical phenotypes of inflammatory myopathies (IIM) patients has not been thoroughly addressed. Assess the CD features among patients with IIM and their relationship with the clinical phenotype and the myositis specific (MSA) and associated antibodies (MAA). For this cross-sectional study, we recruited 99 adult patients classified as IIM from a tertiary center in Mexico. We assessed serum MSA, MAA, and CD-associated autoantibodies (IgA anti-tissue transglutaminase (tTG) and both IgA and IgG anti-deaminated gliadin peptide (DGP)). Patients with highly suggestive serology for CD were then tested for IgG anti-endomysium antibodies, and a duodenal biopsy was performed. 70.7% of patients were positive for at least one antibody. Nine duodenal biopsies were taken, revealing findings compatible with celiac disease in two cases. Subjects with anti-MDA5 antibodies were more likely to have positive anti-tTG IgA antibodies (OR 6.76, 95% CI 1.85-24.62, P = 0.013) and suggestive CD serology (OR 6.41, 95% CI 1.62-25.29, P = 0.009). Patients with anti-Mi2 antibodies were more likely to have positive anti-DGP IgG antibodies (OR 3.35, 95% CI 1.12-9.96, P = 0.039), while positivity for these autoantibodies was less frequent in patients with anti-NXP2 antibodies (OR 0.22, 95% CI 0.06-0.80, P = 0.035). There is a higher prevalence of serologic and definite CD in patients with IIM compared to the general population. Identifying this subgroup of patients may have prognostic and therapeutic implications. Key points • The study estimated a serological celiac disease (CD) prevalence of 70.7% in patients with idiopathic inflammatory myopathies (IIM) and a biopsy-confirmed prevalence of 2%, suggesting that IIM patients should be considered a high-risk population for CD. • We identified a significant association between serological CD and the presence of anti-MDA5 and anti-Mi2 antibodies, suggesting a potential justification for celiac disease screening in this specific subgroup of patients. • The impact of gluten-free diets on IIM patients with serological markers of CD remains untested and warrants further investigation through prospective, randomized studies.

The prevalence, epidemiological characteristics and mortality trends of inflammatory myopathies patients in Oman: the Prevision study.

OBJECTIVES: This research aims to investigate the prevalence, epidemiological characteristics, mortality rates, survival rates and the rate of malignancy in patients diagnosed with inflammatory myopathies (IIM) in Oman. METHODS: This is a longitudinal study, that covered a span of 16 years at eight rheumatology centres in Oman. The study included all adults and paediatric patients diagnosed with different types of idiopathic inflammatory myopathies (IIM) and who fulfil either the Bohan classification criteria or the 2017 EULAR/ACR classification criteria. RESULTS: The study included a total of 116 patient with an average age of 38.78 (±17.61 SD) years. The most prevalent form of myositis was found to be dermatomyositis (DM) 48 (41.38%), followed by polymyositis (PM) 36 (31.03%) and juvenile myositis (JDM) 18(15.52%). However, inclusion body myositis and necrotising myopathy were relatively rare conditions. The prevalence rates for DM, PM and JDM were determined as 2.2, 2.2, and 1.14 per 100,000 population respectively. Cardiac complications were observed in 14.66% of cases. Among the individuals studied, a history of malignancy was present in around 1.72% of cases. ANA antibodies were present in 71.55% of the cases, anti-Jo 1 and anti-RNP/SM antibodies were detected in 8.62%, and Anti-Ro antibodies in 24.14%. The overall mortality rate was found to be 6.90% with a rate of 11.1% among JDM cases. The five-year survival rates for PM, DM and JDM were found to be 94.4%, 91.7% and 89.0% respectively. These rates decline over a 10-year period to 67%, 69% and 83.3% respectively. CONCLUSIONS: The study highlights the prevalence, mortality, and survival rates of IIM in Oman. Patients with JDM had a higher mortality rate. This underscores the significance of using novel healthcare strategies to improve clinical outcomes and meet special requirements for this group of patients.

Myositis Autoantibody Profiles and Clinical Significance in Patients with Inflammatory Myopathies in Southwest China.

BACKGROUND: The purpose of this study is to analyze the distribution of myositis-specific autoantibodies (MSAs) and myositis-associated autoantibodies (MAAs) in patients with idiopathic inflammatory myopathies (IIMs) in southwest China and to explore the relevance between each subtype, each clinical feature, and to explore the relevance between the laboratory indexes. METHODS: For this study, 200 patients with IIMs were tested for myositis autoantibodies. Clinical manifestations and laboratory metrics were collected and the correlations between autoantibodies and clinical phenotypes were analyzed. RESULTS: MSAs were found in 73.5% of the patients. The most frequently MSAs were anti-MDA5 (26.8%), followed by anti-ARS (18.5%). Anti-Ro52 was the most prevalent in MAAs (46.2%). Interstitial lung disease (ILD) and arthralgia were more frequent in anti-MDA5 and anti-Jo-1 positive groups (each p < 0.05). Anti-TIF1-γ and anti-NXP2 were associated with dysphagia (each p < 0.05). Different antibody subtypes were associated with laboratory indicators of response to muscle damage and immune status. Logistic regression showed that anti-MDA5 and anti-Jo-1 were independent risk factors for ILD (OR = 4.542, p = 0.004; OR = 4.290, p = 0.018, respectively) and arthralgia (OR = 7.856, p = 0.000; OR = 5.731, p = 0.004, respectively), whereas anti-TIF1-γ and anti-NXP2 were independent risk factors for dysphagia (OR = 4.521, p = 0.009; OR = 6.889, p = 0.017, respectively). CONCLUSIONS: Different antibody subtypes were associated with specific clinical features. Anti-MDA5 and anti-Jo-1 were independent risk factors for ILD and arthralgia. Anti-TIF1-γ and anti-NXP2 were independent risk factors for dysphagia.

Anti-synthetase syndrome is associated with a higher risk of hospitalization among patients with idiopathic inflammatory myopathy and COVID-19.

Background: Data with fine granularity about COVID-19-related outcomes and risk factors were still limited in the idiopathic inflammatory myopathies (IIMs) population. This study aimed to investigate clinical factors associated with hospitalized and severe COVID-19 in patients with IIMs, particularly those gauged by myositis-specific antibodies. Methods: This retrospective cohort study was conducted in the Renji IIM cohort in Shanghai, China, under an upsurge of SARS-CoV-2 omicron variant infections from December 2022 to January 2023. Clinical data were collected and analyzed by multivariable logistic regression to determine risk factors. High-dimensional flow cytometry analysis was performed to outline the immunological features. Results: Among 463 infected patients in the eligible cohort (n=613), 65 (14.0%) were hospitalized, 19 (4.1%) suffered severe COVID-19, and 10 (2.2%) died. Older age (OR=1.59/decade, 95% CI 1.18 to 2.16, p=0.003), requiring family oxygen supplement (2.62, 1.11 to 6.19, 0.028), patients with anti-synthetase syndrome (ASyS) (2.88, 1.12 to 7.34, 0.027, vs. other dermatomyositis), higher IIM disease activity, and prednisone intake >10mg/day (5.59, 2.70 to 11.57, <0.001) were associated with a higher risk of hospitalization. Conversely, 3-dose inactivated vaccination reduced the risk of hospitalization (0.10, 0.02 to 0.40, 0.001, vs. incomplete vaccination). Janus kinase inhibitor (JAKi) pre-exposure significantly reduced the risk of severe COVID-19 in hospitalized patients (0.16, 0.04 to 0.74, 0.019, vs. csDMARDs). ASyS patients with severe COVID-19 had significantly reduced peripheral CD4+ T cells, lower CD4/CD8 ratio, and fewer naive B cells but more class-switched memory B cells compared with controls. Conclusion: ASyS and family oxygen supplement were first identified as risk factors for COVID-19-related hospitalization in patients with IIMs. JAKi pre-exposure might protect IIM patients against severe COVID-19 complications.

Polymyositis is a rare and favourable outcome subtype of idiopathic inflammatory myopathy in Chinese patients.

OBJECTIVES: To investigate the prevalence and characteristics of typical polymyositis (PM) in Chinese patients with idiopathic inflammatory myopathy (IIM). METHODS: Patients diagnosed with IIM according to the 2017 EULAR/ACR criteria were included. Serological aspects including myositis-specific antibodies (MSA) and pathological data were re-evaluated. The diagnosis of typical PM was strictly done using the pathological criteria, while excluding other IIM subtypes such as dermatomyositis (DM), immune-mediated necrotising myopathies (IMNM), anti-synthetase syndrome (ASS), and sporadic inclusion body myositis (sIBM), based on their respective diagnostic criteria. RESULTS: A total of 544 IIM patients with muscle biopsy were involved, and 129 of them were diagnosed with initial PM according to the 2017 EULAR/ACR criteria. Only 6 (1.1%, 6/544) patients met the strict definition of typical PM after re-evaluation. Patients with typical PM were MSA-negative (100% vs. 35.7%, p=0.003) and had CD8+ T cells surrounding or invading non-necrotic muscle fibres in muscle biopsies (100% vs. 7.8%, p<0.001) compared to the initially diagnosed PM patients. All typical PM patients achieved clinical remission at the second-year follow-up. Typical PM patients had a favourable prognosis compared to MSA-negative IMNM and unspecific myositis patients. CONCLUSIONS: Strictly defined typical PM is a rare clinical subtype in Chinese IIM patients. Typical PM patients with classical pathology were MSA-negative and responded well to treatment and had a favourable prognosis. It is crucial for clinicians to combine clinical, serological, and pathological features to properly distinguish PM from other IIM subtypes.

Cancer Risk and Mortality in Hospitalized Patients With Idiopathic Inflammatory Myopathies in Western Australia.

OBJECTIVE: To compare cancer incidence, type, and survival between patients with idiopathic inflammatory myopathies (IIMs) in Western Australia (WA) and the general population. METHODS: Administrative health data for hospitalized patients with incident IIM (n = 803, 56.5% female, median age 62.0 yrs), classified by a validated algorithm as polymyositis (PM; 36.2%), dermatomyositis (DM; 27.4%), inclusion body myositis (IBM; 17.1%), overlap myositis (OM; 10.7%), and other IIM (8.6%), were linked to WA cancer and death registries for the period of 1980 to 2014. Cancer incidence rates (CIRs) before and after IIM diagnosis as well as cancer mortality were compared with age-, sex-, and calendar year-matched controls (n = 3225, 54.9% female, median age 64 yrs) by rate ratios (RRs) and Kaplan-Meier survival estimates. RESULTS: The prediagnosis CIR was similar for patients with IIM and controls (6.57 vs 5.95; RR 1.11, 95% CI 0.88-1.39) and for patients evolving to DM (n = 220) or other IIM subtypes (6.59 vs 6.56; RR 1.01, 95% CI 0.38-3.69). During follow-up, CIR was higher for all DM (4.05, 95% CI 3.04-5.29), with increased CIR for lung cancer vs controls (1.05 vs 0.33; RR 3.18, 95% CI 1.71-5.47). Cancer post diagnosis shortened life span by 59 months for patients with IIM (103 vs 162 months, P < 0.01), but reduced survival rates were observed only in patients with DM and IBM. CONCLUSION: Cancer risk was not increased prior to IIM, but CIR for lung cancer was increased following DM diagnosis. As cancer reduced survival only in patients with DM and IBM, these data support a strategy of limited cancer screening in IIM.

Causality Assessment Between Idiopathic Inflammatory Myopathies and Lung Cancer: A Bidirectional 2-Sample Mendelian Randomization.

BACKGROUND: Although observational studies have revealed associations between idiopathic inflammatory myopathies (IIMs) and lung cancer (LC), they have not established a causal relationship between these 2 conditions. METHODS: We used a 2-sample Mendelian randomization approach to examine the bidirectional causal associations between IIMs and LC, using single-nucleotide polymorphisms selected from high-quality genome-wide association studies in the FinnGen database. Sensitivity analyses were conducted to assess potential heterogeneity and pleiotropy impacts on the Mendelian randomization results. RESULTS: Our analysis demonstrated a positive causal effect of genetically increased IIM risk on LC (odds ratio, 1.114; 95% confidence interval, 1.057-1.173; p = 5.63 × 10 -5 ), particularly on the lung squamous cell carcinoma subtype (odds ratio, 1.168, 95% confidence interval, 1.049-1.300, p = 0.00451), but not on lung adenocarcinoma or small cell lung cancer. No causal effect of LC on IIMs was identified. Sensitivity analyses indicated that horizontal pleiotropy was unlikely to influence causality, and leave-one-out analysis confirmed that the observed associations were not driven by a single-nucleotide polymorphism. CONCLUSION: Our findings offer compelling evidence of a positive causal relationship between IIMs and LC, particularly with regard to lung squamous cell carcinoma, in the European population. Conversely, there is no evidence of LC causing IIMs. We recommend that LC diagnosis consider the specific characteristics of IIMs.

Vitamin D levels in idiopathic inflammatory myopathy patients: a meta-analysis.

PURPOSE: This meta-analysis aimed to explore correlations between vitamin D and idiopathic inflammatory myopathy (IIM). METHODS: A comprehensive database search was conducted on 13 October 2020. Mean differences (MDs) and aggregated risk ratios (RR) with 95% confidence intervals (CIs) were used to determine the correlation between vitamin D deficiency (VDD) and IIM. Statistical analysis was performed with RevMan 5.4 and Stata15, statistical significance was set at p < 0.05. RESULTS: Search revealed five studies with 286 IIM patients and 480 healthy controls. Results with random-effects modeling indicated that serum vitamin D levels were significantly lower in IIM patients than in healthy controls (MD = -13.10 ng/mL; 95% CI: -16.51 to -9.68; p < 0.00001). No differences were found between patients with IIM and other autoimmune diseases on vitamin D levels (MD =-2.65 ng/mL; 95% CI: -11.31-6.01; p = 0.55). In two studies with 185 IIM patients, those with low vitamin D levels exhibited higher creatine kinase levels (MD = 85.20 IU/L; 95% CI: 72.67-97.73; p < 0.00001) than those with normal vitamin D levels. VDD was correlated with an increased risk of IIM (RR = 3.24, 95% CI: 1.81-5.79; p < 0.0001). CONCLUSION: This meta-analysis showed correlations between vitamin D level and IIM. The results indicated, VDD may be a risk factor for IIM, a determinant of immune dysregulation in IIM, or a consequence of IIM. Also, it implied further research to determine whether vitamin D supplementation is beneficial for patients with IIM.

Hospital admissions from the emergency department of adult patients affected by myopathies.

BACKGROUND AND PURPOSE: Myopathies are associated with classic signs and symptoms, but also with possible life-threatening complications that may require assistance in an emergency setting. This phenomenon is understudied in the literature. We aimed to assess the presentation, management, and outcomes of clinical manifestations potentially related to a muscle disorder requiring referral to the adult emergency department (ED) and hospitalization. METHODS: Anonymized patient data retrieved using the International Classification of Diseases, Ninth Revision codes related to muscle disorders over 4 years were retrospectively analyzed. Medical reports were evaluated to extract demographic and clinical variables, along with outcomes. Two groups were defined based on the presence (known diagnosis [KD] group) or absence (unknown diagnosis [UD] group) of a diagnosed muscle disorder at arrival. RESULTS: A total of 244 patients were included, 51% of whom were affected by a known myopathy, predominantly limb-girdle muscular dystrophies and myotonic dystrophies. The main reasons for ED visits in the KD group were respiratory issues, worsening of muscle weakness, and gastrointestinal problems. Heart complications were less prevalent. In the UD group, 27 patients received a new diagnosis of a specific primary muscle disorder after the ED access, mostly an inflammatory myopathy. Death during hospitalization was recorded in 26 patients, with a higher rate in the KD group and in patients affected by mitochondrial and inflammatory myopathies. Sepsis and dyspnea were associated with increased death risk. CONCLUSIONS: Respiratory complications are the most common reason for myopathic patients accessing the ED, followed by gastrointestinal issues. Infections are severe threats and, once hospitalized, these patients have relatively high mortality.

Cardiovascular risk in myositis patients compared with the general population.

OBJECTIVES: We aimed to evaluate cardiovascular (CV) risk in patients with idiopathic inflammatory myopathies (IIM) compared with healthy controls (HC) and to assess its association with disease-specific features. METHODS: Ninety IIM patients and 180 age-/sex-matched HC were included. Subjects with a history of CV disease (angina pectoris, myocardial infarction and cerebrovascular/peripheral arterial vascular events) were excluded. All participants were prospectively recruited and underwent examinations of carotid intima-media thickness (CIMT), pulse wave velocity (PWV), ankle-brachial index (ABI), and body composition. The risk of fatal CV events was evaluated by the Systematic COronary Risk Evaluation (SCORE) and its modifications. RESULTS: Compared with HC, IIM patients had a significantly higher prevalence of traditional CV risk factors, carotid artery disease (CARD), abnormal ABI and PWV. After propensity score matching (using traditional CV risk factors), the prevalence of CARD and pathological PWV remained significantly higher in IIM than HC. No significant difference in SCORE was observed. The most unfavourable CV risk profile was observed in patients with necrotizing myopathy, especially in statin-induced anti-HMGCR+ patients. The calculated CV risk scores by SCORE, SCORE2 and SCORE multiplied by the coefficient 1.5 (mSCORE) were reclassified according to CIMT and the presence of carotid plaques. SCORE was demonstrated to be most inaccurate in predicting CV risk in IIM. Age, disease activity, lipid profile, body composition parameters and blood pressure were the most significant predictors of CV risk in IIM patients. CONCLUSION: Significantly higher prevalence of traditional risk factors and subclinical atherosclerosis was observed in IIM patients compared with HC.

[Significance of anti-Jo-1 antibody's clinical stratification in idiopathic inflammatory myopathy and disease spectrum].

OBJECTIVE: To investigate the significance of anti-histidyl tRNA synthetase (Jo-1) antibody in idiopathic inflammatory myopathies (IIM) and its diseases spectrum. METHODS: We enrolled all the patients who were tested positive for anti-Jo-1 antibody by immunoblotting in Peking University People's Hospital between 2016 and 2022. And the patients diagnosed with anti-synthetase antibody syndrome (ASS) with negative serum anti-Jo-1 antibody were enrolled as controls. We analyzed the basic information, clinical characteristics, and various inflammatory and immunological indicators of the patients at the onset of illness. RESULTS: A total of 165 patients with positive anti-Jo-1 antibody were enrolled in this study. Among them, 80.5% were diagnosed with connective tissue disease. And 57.6% (95/165) were diagnosed with IIM, including ASS (84/165, 50.9%), immune-mediated necrotizing myopathy (7/165, 4.2%) and dermatomyositis (4/165, 2.4%). There were 23.0% (38/165) diagnosed with other connective tissue disease, mainly including rheumatoid arthritis (11/165, 6.7%), undifferentiated connective tissue disease (5/165, 3.0%), interstitial pneumonia with autoimmune features (5/165, 3.0%), undifferentiated arthritis (4/165, 2.4%), Sjögren's syndrome (3/165, 1.8%), systemic lupus erythematosus (3/165, 1.8%), systemic vasculitis (3/165, 1.8%), and so on. Other cases included 3 (1.8%) malignant tumor patients, 4 (2.4%) infectious cases and so on. The diagnoses were not clear in 9.1% (15 /165) of the cohort. In the analysis of ASS subgroups, the group with positive serum anti-Jo-1 antibody had a younger age of onset than those with negative serum anti-Jo-1 antibody (49.9 years vs. 55.0 years, P=0.026). Clinical manifestations of arthritis (60.7% vs. 33.3%, P=0.002) and myalgia (47.1% vs. 22.2%, P=0.004) were more common in the ASS patients with positive anti-Jo-1 antibody. With the increase of anti-Jo-1 antibody titer, the incidence of the manifestations of arthritis, mechanic hands, Gottron sign and Raynaud phenomenon increased, and the proportion of abnormal creatine kinase and α-hydroxybutyric dehydrogenase index increased in the ASS patients. The incidence of myalgia and myasthenia were significantly more common in this cohort when anti-Jo-1 antibody-positive ASS patients were positive for one and more myositis specific antibodies/myositis associated autoantibodies (P < 0.05). CONCLUSION: The disease spectrum in patients with positive serum anti-Jo-1 antibody includes a variety of diseases, mainly ASS. And anti-Jo-1 antibody can also be found in many connective tissue diseases, malignant tumor, infection and so on.

Miositis aguda asociada a infección por virus influenza. Serie de casos en un hospital pediátrico / Acute myositis associated with influenza infection. Case series in a pediatric hospital

La miositis aguda benigna asociada a influenza es una complicación esporádica. En Argentina, en el año 2022, hubo un aumento temprano de la circulación de influenza y del número total de las notificaciones, con la aparición de miositis secundarias. Serie clínica retrospectiva de nueve pacientes pediátricos que consultaron por dolor e impotencia funcional de extremidades inferiores, y enzimas musculares elevadas, en el hospital Pedro de Elizalde de la Ciudad Autónoma de Buenos Aires, entre agosto y octubre del 2022. En todos se detectó infección por virus influenza y se recuperaron sin secuelas. La miositis aguda benigna es una entidad infrecuente en la infancia, cuyo diagnóstico es predominantemente clínico y de recuperación ad integrum. Debe ser sospechada en pacientes con clínica compatible en contexto de alta circulación viral. La vigilancia epidemiológica aporta herramientas para identificar los virus circulantes y sus posibles complicaciones.

Benign acute myositis associated with influenza is a sporadic complication. In Argentina, in 2022, there was an early increase in influenza circulation and the total number of notifications, with the appearance of secondary myositis. Retrospective clinical series of nine pediatric patients who consulted for pain and functional impotence of the lower extremities, and elevated muscle enzymes, at the Pedro de Elizalde hospital in the Autonomous City of Buenos Aires, between August and October 2022. In all of them, infection by influenza virus and recovered without sequelae. Benign acute myositis is a rare entity in childhood, whose diagnosis is predominantly clinical and recovery ad integrum. It should be suspected in patients with compatible symptoms in a context of high viral circulation. Epidemiological surveillance provides tools to identify circulating viruses and their possible complications.