The aim of current study is to evaluate changes of behavior and presentation of IBD during last 2 decades.

During a 6 months period, the information of IBD patients who attend in IBD outpatient clinics of 11 referral centers in 6 countries collected and based on the first time of diagnosis with IBD, they allocated as group A (those who diagnosed more than 15 years ago), group B (those who involved 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 disease evaluated and compared.

Overall 1430 IBD patients including 1207 UC patients (84.5%), 205 CD patients (14.3%) and 18 cases with indeterminate colitis (1.3%) form 6 countries (Egypt, India, Iran, Pakistan, Poland, Vietnam) included. The participants were originally citizens of 9 countries (figure 1) and 48.1% of them (687 cases) were male. Average age was 37.2 year (range 3 to 83) and 45.8% of them were Caucasian in descent. Average age of participants at the first time of diagnosis with IBD was between 30 and 31 years (range 2 - 84). The extra-intestinal involvement of IBD in groups A and B was more prevalent in comparison with group C (19.6% and 19.2% vs. 13.7%) (P = 0.08 & 0.009 respectively). Relative prevalence of UC subtypes based on anatomic involvement was similar among groups A and B (extensive colitis as the most prevalent subtype, 48.73% and 48.47% respectively) but among those who involved in recent 5 years (group C), the most prevalent subtype is left side colitis ( 38.17%). The most prevalent subtype of CD in group A and B was ileocolic involvement (L3, 25% and 26% respectively) while among those who involved during last 5 years (group C), upper GI involvement (L3+L4) is significantly increased (31% vs. 8% in group A and 6% in group B; P = 0.09 & 0.0009 respectively). The relative prevalence of patients who have not experienced disease flare raised among study groups with a steady slope (group A 15.9%, group B 22.9% and group C 42.38%, P <0.00001). Relative prevalence of majority of presenting symptoms among UC patients in recent 5 years (group C) differs from those who diagnosed more than 15 years ago (group A) and the rate of symptoms such as abdominal pain ( 70.7% vs 54.1%, P = 0.0003), bloating (43.9% vs 20.8%, P = 0.00001) and fatigue (28.9% vs 13.3%, P = 0.0003) have increased and frequency of diarrhea (67.4% vs 80.8%, P = 0.003) has decreased. Among CD patients, the relative prevalence of presenting symptoms is almost similar between new cases in recent years (group C) and those who diagnosed earlier.

in recent 5 years the pattern of UC presentation has changed and the rate of upper GI involvement by CD increased but the relative prevalence of IBD patients with no disease flare increased and rate of extra intestinal involvement decreased which means better understanding and management of disease.