Epidemiology of inflammatory bowel diseases in childhood.

Inflammatory Bowel Disease (IBD) is common in most industrialised countries and childhood IBD accounts for nearly 30% of total cases. Various studies, mostly from Europe and USA have reported epidemiological characteristics of childhood IBD. The incidence figures vary greatly from region to region and within a region over time. Almost all reported studies have documented an increase in the incidence, mainly of Crohn's disease over the last few decades. The reasons for the increase are not clear but epidemiological observations have led to many postulates. Incidence in developing countries is perceived to be low, but limited data suggest that it may not be as uncommon as previously thought. IBD can occur at any age but is rare in infancy. Among childhood IBD, early onset IBD appears to be different epidemiologically and is characterised by predominance of colonic involvement and high positive family history. It has become apparent that only about 25% of childhood Crohn's disease presents with classical triad of abdominal pain, diarrhoea and weight loss. Pediatricians should be aware of atypical manifestations and should maintain high index of suspicion. Though epidemiological studies of childhood IBD done so far have contributed towards understanding of IBD, they have differed in study design, population, time period, age group and case definitions. Unfortunately there are no uniform, clear diagnostic criteria which are evidence based. To address this problem, recently the IBD working group of European Society of Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) has published "The Porto Criteria" which details a consensus based diagnostic criteria for the diagnosis of childhood IBD. This should bring uniformity in ascertainment of newly diagnosed IBD cases. An European multicentre prospective database has also been established to facilitate future epidemiological studies.