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

https://doi.org/10.1016/j.autrev.2020.102531Get rights and content

Highlights

  • The age-standardized mortality rate (ASMR) of 6 auto-immune diseases was computed using the WHO mortality database.

  • The ASMR were generally lower in Europe than in North America, Latin America and Asia.

  • Between 2001 and 2014, there was a significant worldwide decrease of the ASMR of SSc, IIM & AAVs while it increased for SLE and Sjögren's

Abstract

Aim

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.

Methods

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.

Results

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).

Conclusions

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.

Introduction

Autoimmune systemic diseases (AISDs) are a heterogeneous group of conditions characterized by an immune dysregulation resulting in inflammation and multi-organ involvements [1]. The prevalence of autoimmune diseases is currently estimated to range from 4 to 5% of the general population in developed countries [2,3], and is expected to increase globally [4]. The care of patients with AISDs is often challenging [5], and despite recent advances in immunosuppressive treatments [[6], [7], [8]], the burden of AISDs remains high [[9], [10], [11]]. World-wide differences in AISDs mortality are largely multifactorial and involve the role of different genetic backgrounds [12], socio-economic level and access to care [13], the variable efficacy of treatments [14], their side-effects, as well as the burden of comorbidities [15,16]. Also, methodological differences in mortality assessment methods may limit inter-country comparability. As of today, AISD mortality has essentially been studied in limited geographical areas such as at a given institution-, region- or more rarely country-level, mostly using registries or cohorts [10,[17], [18], [19]]. While these approaches have provided important data, inter-country comparisons from different sources are limited and a global overview of AISDs mortality is currently lacking. Noteworthy, worldwide data on AISD mortality are of major interest to policymakers as well as to physicians involved in the care of these rare diseases.

Here, we used publicly available data from the World Health Organization (WHO), to analyze worldwide temporal trends of mortality data for six AISDs, namely Systemic Lupus Erythematosus (SLE), Systemic Sclerosis (SSc), Sjögren's Syndrome (SS), Idiopathic Inflammatory Myopathies (IIM), Mixed Connective Tissue Disease (MCTD) and Anti-Neutrophil Cytoplasm Antibody (ANCA)-Associated Vasculitis (AAV).

Section snippets

Data sources & handling

Data of cause-specific deaths were retrieved from the publicly available WHO mortality database (http://www.who.int/healthinfo/mortality_data/). Retrieved data included the number of cause-specific deaths, age category for each country, year and gender. Population data according to sex and age were retrieved from the United Nations World prospects database (https://population.un.org/wpp/Download/Standard/Population/). For geographical analysis, the countries were grouped as follows: Europe,

Systemic lupus erythematosus

For the year 2014, 6418 SLE-related deaths occurred in 84 countries (Fig. 1A & Suppl. Table 1), corresponding to 0.021% of all deaths and yielding a global ASMR of 2.68 (95%CI: 2.62–2.75) per million inhabitants. The ASMR was 4.53 (4.40–4.65) for women and 0.79 (0.73–0.84) for men. The ASMR ranged from 0.11 in Morocco to 27.1 deaths per million in Saint Lucia (Fig. 2 & Supplementary Table 1). For the year 2014, the ASMR of SLE in Europe (1.06 [95%CI: 0.98–1.13] deaths/million) was significantly

Discussion

In this study, we used world-wide data from the World Health Organization to analyze worldwide mortality data of 6 auto-immune and systemic conditions, namely SLE, SSc, SS, IIM, MCTD and AAV. One main strength of the study is the use of standardized mortality rates as a way to account for differences in the heterogenous age structure of the populations studied. Further, we were able to analyze temporal changes in all-cause disease-specific mortality data over a span of 14 years.

While not

Conclusions

Altogether, we used world-wide data from the World Health Organization to analyze detailed temporal trends of standardized all-cause disease-specific mortality rates for 6 major systemic auto-immune conditions. Our results reveal major differences in mortality between those 6 AISDs, and the generally better prognosis in Europe versus other geographical regions, including North America. Those results further highlight the impact of world-wide inequities and major gaps in access to care and

Disclosures

None.

Funding

None.

Acknowledgements

The authors wish to thank Ms. Thuong for her invaluable assistance in the handling of the manuscript. The study was performed based on publicly available WHO data. However, the WHO was not involved in this study which was performed independently by its authors.

References (24)

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