SAT0684 Appendicitis and the risk of newly diagnosed systemic sclerosis: a nationwide, population-based, case-control study in taiwan
Authors: H.-H. Chen, K.-L. Lai, D.-Y. Chen
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Previous studies suggested that patients with systemic sclerosis (SSc) had specific alterations in the gastrointestinal microbiota, including increased levels of pathobiont genera, such as Fusobacterium. Local expansion of Fusobacterium was also found in children with acute appendicitis. However, no prior study had explored the association between incident SSc and prior appendicitis. <h3>Objectives</h3> To explore the association between appendicitis and the risk of incident systemic sclerosis (SSc). <h3>Methods</h3> Using the 2003–2012 claims data of the entire population in Taiwan, we identified 1595 patients with a new diagnosis SSc (ICD-9-CM 710.1) validated by a thorough review of the original medical record from 2006 to 2012 as SSc cases. We also selected 15 950 individuals who never had a diagnosis of SSc during 2003–2012 matching SSc cases (1:10) for age, sex, and the year of index date from claims data of a one million representative Taiwanese population as non-SSc controls. The index date was defined the first date of SSc diagnosis in the SSc group and the first date of ambulatory visit for any reason in the control group. Using conditional logistic regression analysis, The association between appendicitis (ICD-9-CM 540–543) and the risk of incident SSc was tested by estimating odds ratios (ORs) with 95% confidence intervals (CIs) controlling for potential confounders, including Charlson comorbidity index, a history of periodontal disease (ICD-9-CM 523), salmonella infection (ICD-9-CM 003), and intestinal infection (ICD-9-CM 009). We also performed sensitivity analyses by varying the definition of appendicitis according to the status of receiving primary appendectomy. <h3>Results</h3> The mean ±SD age was 51±15 years in both cases and controls. The proportion of women was 77.5%. Appendicitis was identified in 17 (1.1%) of 1595 SSc cases and 81 (0.5%) of 15 950 non-SSc controls before the index date had a history of appendicitis. A significant assciation between appendicitis and the risk of SSc was demonstrated (OR, 2.03; 95% CI, 1.14–3.60) after adjustment for potential confounders. The association between appendicitis and SSc risk was still statistically significant using various definitions of tonsillitis based on the status of primary appendectomy. <h3>Conclusions</h3> The present study reveals an association between SSc risk and a history of appendicitis. <h3>References</h3> [1] Volkmann ER, Hoffmann-Vold AM, Chang YL, Jacobs JP, Tillisch K, Mayer EA, et al. Systemic sclerosis is associated with specific alterations in gastrointestinal microbiota in two independent cohorts. BMJ open gastroenterology2017;4(1):e000134. [2] Rogers MB, Brower-Sinning R, Firek B, Zhong D, Morowitz MJ. Acute Appendicitis in Children Is Associated With a Local Expansion of Fusobacteria. Clinical infectious diseases: an official publication of the Infectious Diseases Society of America2016;63(1):71–8. <h3>Acknowledgements</h3> The authors would like to thank the Biostatistics Task Force of Taichung Veterans General Hospital, Taichung, Taiwan, ROC for statistical support. <h3>Disclosure of Interest</h3> None declared