531Investigating systemic autoimmune diseases as a group of causes of death: mortality burden and comorbidities. (2nd September 2021)

• Record Type: Journal Article
• Authors: Mitratza, Marianna; Klijs, Bart; Hak, A Elisabeth; Kardaun, Jan WPF; Kunst, Anton E
• Is Part Of: International journal of epidemiology. Volume 50(2021)Supplement 1
• Publication Date: 2021-09-02
• Subjects: Epidemiology -- Periodicals; 614.4
• DOI: 10.1093/ije/dyab168.445
• Languages: English
• ISSNs: 0300-5771

Abstract

Abstract: Background: Systemic autoimmune diseases (SAIDs) have chronic trajectories and share characteristics of self-directed inflammation and aspects of clinical expression. Nonetheless, burden-of-disease studies rarely investigate them as a distinct category. This study aims to assess the mortality rate of SAIDs as a group and to evaluate co-occurring causes of death. Methods: We used death certificate data in the Netherlands, 2013-2017, (N = 711, 247) and constructed a SAIDs list (4-position ICD-10). The mortality rate of SAIDs as underlying Cause of Death (CoD), non-underlying CoD, and any-mention CoD was calculated. We estimated age-sex-standardized observed/expected ratios to assess comorbidities in deaths with SAID relative to the general deceased population. Results: We observed 3, 335 deaths with SAID on their death certificate (0.47% of all deaths). The mortality rate of SAID was 14.6 per million population as underlying CoD, 28.0 as non-underlying CoD, and 39.7 as any-mention CoD. The mortality rate was higher for females and increased exponentially with age. SAID-related deaths were positively associated with all comorbidities except for solid neoplasms and mental conditions. Particularly strong was the association with musculoskeletal (O/E=3.38, 95% CI[2.98, 3.82]), other genitourinary (O/E=2.73, 95% CI[2.18, 3.38]), blood (O/E=2.02, 95% CI[1.70, 2.39]), skin and subcutaneous tissue (O/E=1.95, 95% CI[1.54, 2.45]), and infectious diseases (O/E=1.85, 95% CI[1.70, 2.01]), as well as influenza (O/E=2.71, 95% CI[1.74, 4.03]). Conclusions: Systemic autoimmune diseases constitute a rare group of causes of death, but contribute to mortality through multiple comorbidities. Classification systems could be adapted to better encompass these diseases as a category. Key messages: Reclassification of readily available data provides useful estimates for the mortality burden of systemic autoimmune diseases in the population.