Worldwide trends in all-cause mortality of auto-immune systemic diseases between 2001 and 2014

To describe changes in the 2001-2014 mortality of 6 autoimmune systemic diseases (AISDs), namely Systemic Lupus Erythematosus (SLE), Systemic Sclerosis (SSc), Idiopathic Inflammatory Myopathies (IIM), Sjögren's Syndrome (SS), Mixed Connective Tissue Disease (MCTD) and ANCA-associated vasculitis (AAV) at the country-, continent-, and world-levels.

Mortality data were retrieved from the World Health Organization (WHO) mortality database for each disease, based on ICD-10 codes. We computed age-standardized mortality rate (ASMR) as the estimated number of deaths per million inhabitants and its 95% confidence interval (95%CI). The association between gender, geographical areas and disease-specific mortality was analyzed using multivariate Poisson regression. The 2001-2014 temporal trends were analyzed using Jointpoint software.

In 2014, the worldwide ASMR for SLE was 2.68 (95%CI: 2.62-2.75) deaths/millions inhabitants, 1.46 (1.42-1.51) for SSc, 0.47 (0.44-0.49) for IIM, 0.17 (0.15-0.18) for SS, 0.11 (0.10-0.13) for MCTD and 0.53 (0.50-0.56) for AAV, with ASMRs generally lower in Europe than in North America, Latin America and Asia. Between 2001 and 2014, the worldwide ASMR decreased significantly for SSc (-0.71%/year), IIM (-1.65%/year) and AAV (-1.01%/year; p < .001 for all) and increased for SS (+1.53%/year, p = .01). The worldwide ASMR of SLE decreased significantly between 2001 and 2003 (-6.37%, p < .05) before increasing slightly between 2004 and 2014 (+0.58%, p < .01).

We observed a strong heterogeneity of standardized mortality rates across all countries analyzed for 6 autoimmune diseases. Those results further highlight the impact of world-wide inequities and major gaps in access to care and strategies for diagnosis and management of rare diseases, a crucial finding for world-wide physicians, patient associations and policy makers.