Inflammatory bowel disease evolution in the past two decades: a chronological multinational study.

Background: The multifactorial nature of inflammatory bowel disease (IBD), which manifests differently in individuals creates a need for a better understanding of the behaviour and pattern of the disease due to environmental factors. The current study aimed to study the changes in IBD behaviour, presentation, and characteristics in patients over the past two decades with a goal of improving patients' diagnosis, management and outcomes. Methods: During a 6-month period (1/02/2022-30/07/2022), the information of patients with IBD who attended IBD outpatient clinics of 11 referral centre's in six countries was collected, and based on the first time of diagnosis with IBD, they were allocated as group A (those who were diagnosed more than 15 years ago), group B (those who were diagnosed with IBD between 5 and 15 years ago) and group C (IBD cases who diagnosed in recent 5 years). Then the most prevalent subtypes and characters of the disease are evaluated and compared to make clear if the presenting pattern and behaviour of the disease has changed in the last 2 decades. Findings: Overall 1430 patients with IBD including 1207 patients with ulcerative colitis (UC) (84.5%) and 205 patients with Crohn's disease (CD; 14.3%) included. Mean age of participants at the first time of diagnosis with IBD was 30 years. The extra-intestinal involvement of IBD in groups A and B was more prevalent in comparison with group C. Most of those in groups A & B had academic education but in group C, the most prevalent educational status was high school or diploma (P = 0.012). In contrast to groups A and B, the relative prevalence of medium socioeconomic level in group C had decreased (65%). Relative prevalence of UC subtypes was similar among groups A and B (extensive colitis as most prevalent) but in group C, the most prevalent subtype is left side colitis (38.17%). The most prevalent subtype of CD in groups A and B was ileocolic involvement while in group C, upper GI involvement is significantly increased. The rate of food sensitivity among groups A and B was more than group C (P = 0.00001). The relative prevalence of patients with no flare has increased with a steady slope (P < 0.00001). Relative prevalence of presenting symptoms among patients with UC in group C differs and nowadays the rate abdominal pain (70.7%) and bloating (43.9%) have increased and frequency of diarrhoea (67.4%) has decreased. Interpretation: In the recent 5 years, the pattern of UC presentation has changed. The rate of upper GI involvement in CD and relative prevalence of patients with no disease flare increased and the rate of extra intestinal involvement decreased. Funding: None.