| Background:Little is known about the clinical features and true survival risk factors in Chinese Han population inflammatory myopathy patients. Pulmonary hypertension (PAH) has been reported in association with various connective tissue diseases (CTD). However, the prevalence of PAH in polymyositis and dermatomyosits (PM/DM) patients is uncertain, and little is known about the clinical features and independent predictator for PAH in PM/DM patients. Further, at present, the reliability and validity of the myositis disease activity assessment tool was not assessed in China, and the feasibility of MDAAT in assessing PM/DM patients in China was unknown.Objective:We conducted the current study to:(1) investigate the clinical features of the idiopathic inflammatory myopathies (IIM) with Chinese Han population patients. (2) estimate the point prevalence of pulmonary hypertension (PAH) and identify risk factors for PAH in a large cohort of IIM patients; (3) test the reliability and discrimination validity and clinical value of the Myositis Disease Activity Tool in Chinese patients with Polymyositis/Dermatomyositis (PM/DM); (4) to study the long-term outcome and true survival indicators of IIM through a retrospective study of Chinese Han population patients.Methods:(1). The medical records of consecutive IIM patients in a cohort of China-Japan Friendship were reviewed retrospectively between January 1986 and April 2009. The primary outcome was determined with mortality. The secondary outcomes for survival patients were cumulative organ damage and disease activity, health status, and disability, which were assessed with Myositis Damage Index, Myositis Disease Activity Assessment Tool, Health Assessment Questionnaire Disability Index, and the Modified Rankin Scale, respectively. Potential independent predictators for PAH and mortality were analyzed with the multivariate Logistic regression analysis and multivariate Cox regression model, respectively. (2). Fifty-four PM/DM patients including 18 PM and 36 DM were enrolled in this prospective study between January 2009 and June 2010 in China-Japan Friendship Hospital of Ministry of Health. The disease activity was assessed by the MDAAT. The reliability and discrimination validity were assessed with test-retest reliability, interrater reliability, correlation and t-test analysis.Results:(1). A total of 188 IIM patients were enrolled in our study. All patients were followed up with a mean of 7.5 years after disease onset. Mean age at onset (±standard deviation) was 43.8±15.8 years and male to female ratio was 1:2.1. Twenty patients had PAH, of them,11 patients had mild PAH,7 patients had moderate PAH,2 patients had severe PAH. In addition, among the PAH patients, there were four types including PM/DM complicated with PAH (n=7,35%), PM/DM complicated with interstitial lung diasease (ILD) and PAH (n=6,30%), PM/DM complicated with CTD and PAH (n=3,15%), PM/DM complicated with CTD,ILD and PAH (n=4,20%). The independent predictators for PAH in PM/DM patients were elevated IgM level at diagnosis (OR 24.8,95%CI 1.76～350, P=0.017) and anti-ENA antibody positive at the disease course prior to or at the time of PAH diagnosis (OR 65.9,95%CI 2.5～1761, P=0.012). (2). Disease related death occurred in 17%of the patients. The 1-,3-,5-,10-,15- and 20- year survival rates were 93.6%, 90.2%,88.7%,81%,73.6%and 65.6%. The independent risk factors for mortality were age at disease onset [hazard ratio (HR):1.05,95% CI 1.02-1.08], the presence of cancer (HR:6.02,95%CI 2.21-16.38), and an elevated IgA level at diagnosis (HR:3.29,95%CI 1.27,8.57). At the end of the follow-up,29 patients manifested drug withdrawal within an average 4.1 years (range 0.5-15.2 year), most patients (85.9%) had no disease activity and 130 patients (83.4%) had no disability. (3). MDAAT reliability analysis indicated eight items (constitutional, cutaneous, skeletal, gastrointestinal, pulmonary, cardiovascular, muscle and global) have good reliability, and had good discrimination validity in all the items excluding cardiovascular items, but not constructive validity.Conclusions:(1). The PM/DM complicated with PAH were not rare, the point prevalence of PAH was 10.6%in our cohort patients with PM/DM. Most of patients were foud mild to moderate PAH (90%). The independent predictators for PAH in PM/DM patients were elevated IgM level at diagnosis and anti-ENA antibody positive at the disease course prior to or at the time of PAH diagnosis. (2). The long-term outcomes of IIM patients in our cohort have improved dramatically, and are better than those previously estimated in Caucasians. Those patients most likely to survive had a high chance of reaching stable disease status, and obtained long-term or possibly permanent remission to a large extent. (3). MDAAT has good reliability and discrimination validity in assessing the disease activity of Chinese patients with PM/DM, and could be used to assess the disease activity and therapy effects in Chinese patients. However, the construct validity needed to further study.
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