P836 Trends in the prevalence of Inflammatory Bowel Disease in Lithuania during 2001-2020

Abstract Background The prevalence of inflammatory bowel disease (IBD) is increasing worldwide, affecting millions of individuals. The highest incidence and prevalence are found in Northern Europe and Northern America. There is a lack of new epidemiological studies in the Eastern European region. The objective of this study was to assess changes in the prevalence of IBD in Lithuania during two last decades. Methods Data on the prevalence of Crohn's disease (CD) and ulcerative colitis (UC) (ICD-10 code K50, K51) in Lithuania during 2001-2020 were obtained from the Institute of Hygiene, where the data were systematized from the Mandatory Health Insurance Information System. Changes in the prevalence trends in men and women, children and adults during 2001-2020 were assessed using Joinpoint regression analysis. Results In 2020, the overall prevalence of CD was 33/100,000 and the prevalence of UC was 117/100,000. Gender differences in the prevalence of IBD were not significant. The prevalence of CD among adults in Lithuania has increased 3-fold over 20 years, while the prevalence of UC has increased 4-fold. During 2001-2020, the average annual increase in UC prevalence (8.0%/year, p<0.001) was higher than in CD (6.3%/year, p<0.001). Also, it shows increased UC/CD ratio: in 2001, the ratio was 2.5:1, while in 2020, was observed a higher UC/CD ratio 3.5:1. When comparing changes in the prevalence of IBD, some differences were observed between adults and children. During 2001-2020, the average annual growth rate of CD in children increased not significantly (2.1%/year, p>0.05), while for adults, a significant increase was observed (6.8%/year, p<0,001). Similar trends were noticed in the assessment of the prevalence changes of UC: during 2001-2020, the prevalence of UC in children increased slightly (3.1%/year, p>0.05), while significant growth was observed for adults (7.8%/year, p<0.001). When comparing the children prevalence ratio of CD and UC, it remained almost the same over 20 years, and it was found that CD is more commonly diagnosed in children than UC (CD/UC ratio in 2001 was 1.8:1, while in 2020, it was 1.7:1). In adults, CD/UC ratio was opposite of children, and has changed during 2001-2020: CD/UC ratio in 2001 was 1:2.9, while in 2020, it was 1:3.7. Conclusion The results show that the prevalence of IBD in adults is steadily increasing, while the number of cases in children has not changed significantly over 20 years. Also, it was observed, that Crohn's disease is diagnosed at younger age than ulcerative colitis, which is more commonly diagnosed in older age.