Objective-To determine the prevalence of myositis specific autoantibodies (MSAs) and several myositis associated autoantibodies (MAAs) in a large group of patients with myositis. Methods-A total of 417 patients with myositis from 11 European countries (198 patients with polymyositis (PM), 181 with dermatomyositis (DM), and 38 with inclusion body myositis (IBM)) were serologically analysed by immunoblot, enzyme linked immunosorbent assay (ELISA) and/or immunoprecipitation. Results-Autoantibodies were found in 232 sera (56%), including 157 samples (38%) which contained MSAs. The most commonly detected MSA was anti-Jo-1 (18%). Other anti-synthetase, anti-Mi-2, and anti-SRP autoantibodies were found in 3%, 14%, and 5% of the sera, respectively. A relatively high number of anti-Mi-2 positive PM sera were found (9% of PM sera). The most commonly detected MAA was anti-Ro52 (25%). Anti-PM/Scl-100, anti-PM/Scl-75, anti-Mas, anti-Ro60, anti-La, and anti-U1 snRNP autoantibodies were present in 6%, 3%, 2%, 4%, 5%, and 6% of the sera, respectively. Remarkable associations were noticed between anti-Ro52 and anti-Jo-1 autoantibodies and, in a few sera, also between anti-Jo-1 and anti-SRP or anti-Mi-2 autoantibodies. Conclusions-The incidence of most of the tested autoantibody activities in this large group of European patients is in agreement with similar studies of Japanese and American patients. The relatively high number of PM sera with anti-Mi-2 reactivity may be explained by the use of multiple recombinant fragments spanning the complete antigen. Furthermore, our data show that some sera may contain more than one type of MSA and confirm the strong association of anti-Ro52 with anti-Jo-1 reactivity.
ObjectivesTo assess the association between inflammatory lung disease and the risk of developing idiopathic inflammatory myopathies.MethodsA population-based case–control study was conducted. Adult myositis cases, identified from the Swedish inpatient registry (diagnosed between 1995 and 1997), and randomly selected controls matched to cases on the date of birth, gender and residency, were asked to fill out a questionnaire with questions on lifestyle, environmental exposures and health. Eventually, 100 cases and 402 controls responded to the questionnaire and were included in the analyses. Exposure was defined as self-reported preceding inflammatory lung diseases (pneumonia, tuberculosis or sarcoidosis). The association between the exposure and risk of developing myositis was evaluated by calculating OR together with 95% CIs in logistic regressions.Results42 (42%) cases and 112 (28%) controls reported preceding inflammatory lung disease. Median duration between inflammatory lung disease and first symptom of myositis was 30 years. We observed a significant association between self-reported history of lung disease at study inclusion and diagnosis of myositis (crude OR=1.8 (1.1 to 2.9); smoking adjusted OR=1.9 (1.2 to 3.1)). We further identified a modestly increased, yet non-significant, association between preceding inflammatory lung disease (prior to index year) and diagnosis of myositis (smoking adjusted OR=1.6 (0.9 to 2.8)). The association was more pronounced among the cases of myositis with concurrent interstitial lung disease (OR=3.8 (1.0 to 14.5)).ConclusionsPatients with preceding inflammatory lung disease tend to have an increased risk of developing myositis compared to those without. The effect was more pronounced among patients with myositis with concurrent interstitial lung disease. Thus inflammatory lung disease may constitute a risk factor for myositis.
Background Although the etiology of inflammatory myopathies is unclear, there are data indicating that myositis occurs as a result of complex interactions between genes and environmental/life style factors. Objectives To assess the association between lung disease and the risk of developing inflammatory myopathies, myositis. Methods In this population-based case-control study, 179 incident adult myositis cases diagnosed between 1995 and 1997 were identified from the Swedish inpatient registry. Verification of diagnosis was performed through patient records. The analysis was based on responses from a questionnaire on exposures to environmental factors from 100 cases that were alive and fulfilled the inclusion criteria and from 402 randomly selected population controls matched to cases on birth of date, gender and residency. Exposure was based upon self-reports of preceding inflammatory lung disease (pneumonia, tuberculosis or sarcoidosis). The association between inflammatory lung disease and risk of developing myositis was evaluated by calculating odds ratio (OR) together with 95% confidence interval (CI) by means of logistic regression. Results There was an association between preceding inflammatory lung disease and diagnosis of myositis: adjusted OR 1.5, 95% CI 0.9-2.6. The median duration between the lung disease and first symptom of myositis was 30 years. Conclusions Subjects with preceding inflammatory lung disease had an increased risk of developing myositis compared to those without such disease. Inflammatory lung disease could thus be a potential risk factor for onset of inflammatory myopathies, myositis, or a parallel phenomenon. Disclosure of Interest None Declared
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