Still's disease (SD) is often considered a benign disease, with low mortality rates. However, few studies have investigated SD mortality and its causes and most of these have been single-center cohort studies. We sought to examine mortality rates and causes of death among French decedents with SD. We performed a multiple-cause-of-death analysis on data collected between 1979 and 2016 by the French Epidemiological Center for the Medical Causes of Death. SD-related mortality rates were calculated and compared with the general population (observed/expected ratios, O/E). A total of 289 death certificates mentioned SD as the underlying cause of death (UCD) (n = 154) or as a non-underlying causes of death (NUCD) (n = 135). Over the study period, the mean age at death was 55.3 years (vs. 75.5 years in the general population), with differences depending on the period analyzed. The age-standardized mortality rate was 0.13/million person-years and was not different between men and women. When SD was the UCD, the most frequent associated causes were cardiovascular diseases (n = 29, 18.8%), infections (n = 25, 16.2%), and blood disorders (n = 11, 7.1%), including six cases (54%) with macrophage activation syndrome. As compared to the general population, SD decedents aged <45 years were more likely to die from a cardiovascular event (O/E = 3.41, p < 0.01); decedents at all ages were more likely to die from infection (O/E = 7.96-13.02, p < 0.001).
Keywords: adult-onset Still’s disease; epidemiology; hemophagocytic lymphohistiocytosis; mortality; systemic-onset juvenile idiopathic arthritis.