Background Antisynthetase syndrome (ASS) can be a life-threatening condition. Patients with ASS in the context of idiopathic inflammatory myositis (IIM) have been described to have a worse prognosis compared to patients either with dermatomyositis (DM) or polymyositis (PM) alone.
Objectives To evaluate survival and mortality in a large cohort of Spanish patients with anti-Jo1 ASS and compare it with mortality rates of Spanish general population.
Methods From March 2011 to June 2014 we conducted a national multicentre study, including retrospective and prospective data, among members of the GEAS-IIM Group of the SEMI. Clinicians from 18 Spanish centers participated in the development of a registry of patients with Anti-Jo1 ASS. For data collection a specific electronic database including broad information about demographic and clinical data was developed. Continuous variables were compared by the t-student or non-parametric Mann-Whitney tests when appropriated, while X2 test were used to compare categorical variables. The Kaplan-Meier method and long-rank tests were used to compare survival between groups. The standardized mortality ratio (SMR) was calculated using the Spanish mortality registry. Results were expressed with its 95% interval confiance (IC).
Results A total of 148 anti-Jo1 ASS patients, 90 women (60.8%), were included in the study. Mean (SD) age at diagnosis was 50.8 (16) years. Range follow-up was 1.3 to 412 months [mean (SD) 95 (76.4) months], with only 12 patients with a follow-up fewer than 12 months. Fifteen percent of patients had ILD as the unique main ASS clinical manifestation, other 15% had myositis and 69.3% had both ILD and myositis. Thirty seven patients (25%) died after a median follow-up of 70.3 months (range 4.9 – 308 months). The SMR (95%IC) was 4.77 (3.31-6.67). Main causes of death included respiratory failure (6.8%), cancer (6.1%), infection (4.1%), myositis (2.7%) and acute cardiovascular events (1.3%). A directly ASS-related death were considered in 18 patients (46.6%). Estimated survival rate (95% IC) was 87.5% (81.6% - 93.4%) and 75.4% (66.4% - 84.4%) at 5 and 10 years respectively. Median survival rate (95% IC) was 20.3 years (13.8-26.8 years). No difference in survival was found between patients with myositis (DM or PM) and those with ILD without associated myopathy. The presence of cancer (p=0.02) and an advanced age at ASS diagnosis (p<0.0001) were the unique clinical features significantly related to poorer survival rates.
Conclusions Mortality in ASS patients is four-fold and a half higher than in the general population. Mortality can be directly attributed to ASS in near a half of the cases. Respiratory failure, cancer and infection are the main causes of death. Estimated survival rate at 10 years is around 75%.
Marie I. Morbidity and mortality in adult polymyositis and dermatomyositis. Curr Rheumatol Rep.2012;14:275-285.
Disclosure of Interest None declared