Background/Purpose: Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by diverse clinical manifestations. The risk factors of SLE included genetic factors and environmental factors. A recent study showed that females younger than fifty-year-old with history of appendectomy had a 2.27-fold higher risk of SLE than control groups. However, the association of appendicitis with SLE still needed to be elucidated. The Taiwanese National Health Insurance Research Database (NHIRD) had facilitated population-based epidemiological studies. Therefore, we conducted a nationwide case-control study to investigate the association between appendicitis and SLE in Taiwan.

Methods: Six thousand one hundred thirty-seven patients were selected as SLE cases from the Taiwanese National Health Insurance Research Database from 2003 to 2013. Nine hundred fifty-three thousand six hundred ninety-nine individuals without SLE diagnosis between 2007 and 2012 were recruited to match the SLE cases, with a 1:6 ratio by age, sex and year of SLE index date. A multivariable conditional logistic regression model was applied to calculate the odds ratio (OR) and 95% confidence interval (CI) for the association of appendicitis history with the development of SLE after controlling for potential confounders. Sensitivity analyses were conducted using various definitions of appendicitis.

Results: The average age was 38-year-old in both groups. The proportion of females was 86.5%. 77 (1.3%) participants out of SLE cases and 199 (0.5%) participants out of non-SLE controls had an appendicitis history before the index date. After adjusting for potential confounding factors, appendicitis was associated with an increased risk of SLE (adjusted OR, 1.91; 95% CI, 1.38–2.64). The significant risk is preserved under different definitions of appendicitis.

Conclusion: This study revealed that a history of appendicitis was significantly associated with an increased risk of SLE.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/association-between-appendicitis-and-the-risk-of-systemic-lupus-erythematosus-a-population-based-case-control-study/