Background Mixed connective tissue disease (MCTD) is a systemic autoimmune disorder, accompanied by chronic inflammation involving several organs. MCTD was first described by “Sharp et al.” in 1972 but there is still little known about the long-term outcome of patients and factors influencing the mortality in MCTD.

Objectives To study the survival rate and prognostic indicators of MCTD in a large Hungarian patient population.

Methods Two hundred and eighty patients with MCTD diagnosed between 1979 and 2011 were prospectively followed. Clinical features, autoantibodies and mortality data were assessed. Prognostic factors for survival were investigated and survival was calculated from the time of the diagnosis by Kaplan-Meier method.

Results A total of 22 of 280 patients died during the follow-up period: the causes of death were pulmonary arterial hypertension (PAH) in 9 patients, thrombotic thrombocytopenic purpura in 3 patients, infections in 3 patients and 7 patients died due to cardiovascular events. The 5, 10, 15 year survival rates after the diagnosis was established were 98%, 96% and 88%. The deceased patients were younger at the diagnosis of MCTD compared to those patients who survived (35.5±10.4 vs. 41.8±10.7 years; p<0.03), while there was no difference in the duration of the disease (p=0.835). Our cohort study showed that the presence of cardiovascular events (p<0.0001), esophageal hypomotility (p=0.04), serositis (p<0.001), secondary antiphospholipid syndrome (p=0.039) and malignancy (p<0.001) was significantly higher in the deceased MCTD patients. The presence of anti-cardiolipin (p=0.019), anti-β2-glycoprotein I (p=0.002) and anti-endothelial cell antibodies (p=0.002) increased the risk of mortality.

Conclusions Overall, PAH remained the leading cause of death in patients with MCTD. The prevalence of cardiovascular morbidity and mortality, malignancy and thrombotic events is increasing during the disease course of MCTD and these factors negatively influence the survival. The presence of antiphospholipid antibodies raised the risk of mortality.

Disclosure of Interest None Declared