The Asia-Pacific region has been marked as an area with a low incidence of inflammatory bowel disease (IBD), although confusion always existed as to whether this low incidence was a result of low diagnostic awareness, a high incidence of infective diarrhoea and its diagnostic overlap or a true low incidence. As epidemiological studies from this region are being made available it is clear that the incidence and prevalence rates of IBD in Asia-Pacific region are low compared with Europe and North America. They are however, increasing rapidly. There are substantial variations in the incidence and prevalence rates of IBD in various ethnic groups in Asia. The highest incidence rates are recorded from India, Japan and the Middle East and there exists a genetic predisposition of South Asians (Indians, Pakistanis and Bangladeshis) to ulcerative colitis (UC). It appears that certain racial groups are more prone than others to develop IBD. For instance, Indians in South-East Asia have higher rates than Chinese and Malays. While there is a host genetic predisposition, environmental factor(s) may be responsible for this difference. The clinical phenotypes and complication rates of Asian IBD resemble those of the Caucasian population in general, but some heterogeneity is observed in different regions of Asia. There is no evidence of a north-south or an east-west divide in the Asia-Pacific region. The available studies suggest an increasing incidence of UC in the Asia-Pacific region and hence it is an appropriate time to launch well-designed epidemiological studies so that etiopathogenetic factors can be identified. There is a male predominance in Crohn's disease in the Asian population. The NOD2/CARD15 gene is not associated with CD in the Japanese, Korean, Chinese and Indian population.
In this pilot study we found some evidence that use of NCB-02 enema may tend to result in greater improvements in disease activity compared to placebo in patients with mild-to-moderate distal UC. The role of NCB-02 as a novel therapy for UC should be investigated further.
Although Crohn's disease is thought to be rare and intestinal tuberculosis common in India, Crohn's disease is being reported more often. However, there is a lack of systematic study on Crohn's disease from India. In this analysis of data from three inflammatory bowel disease clinics (two in northern India and one in eastern India), criteria for Crohn's disease were applied retrospectively: (1) World Health Organization (WHO) criteria; or (2) compatible histology (European Crohn's and Colitis Organization) or failure of response to 4-8 weeks of anti-tuberculosis therapy (Asia-Pacific guidelines); or (3) compatible macroscopic, radiologic, colonoscopic features (European Crohn's and Colitis Organization). Others were classified as probable Crohn's disease. The Montreal classification was used for disease phenotype. Age at onset and duration of symptoms (182 patients, 117 male) were 34.5 (+/-13.6; 7-73) years and 3.0 (+/-5.8; 0.1-36) years, respectively. Diarrhea (68%), abdominal pain (62%), and weight loss (57%) were common. The common intestinal complications were occult (27%) and overt (40%) gastrointestinal bleeding and obstruction (28%). There were 141 (78%) and 41 (22%) with definite and probable Crohn's disease respectively. Of 147 (81%) available histopathology specimens (endoscopic biopsy in 110; 75%), 31 (21%) had granuloma. Seventy-one out of 166 (43%) had received anti-tuberculosis therapy in the past. Results from the Montreal classification were as follows: age at onset, A1:A2:A3 6%:64%:30%; location of disease, L1:L2:L3:L4 32%:41%:23%:4%, and disease behavior, B1:B2:B3 51%:24%:25%. Twenty-six (15%) and 31 (17%) patients had upper gastrointestinal and perianal modifiers. The drugs used were: aminosalicylates (128, 70%), steroids (76, 42%), azathioprine (53, 29%), methotrexate (4, 2%), and salazopyrine (14, 8%). Sixty-six (36%) patients underwent surgical treatment. We concluded that the phenotype of Crohn's disease in India is very similar to that described in other regions of Asia and the West, except for a delay in diagnosis and a more complicated disease at diagnosis.
The diversity and basic functional attributes of the gut microbiome of healthy Indians is not well understood. This study investigated the gut microbiome of three Indian communities: individuals residing in rural and urban (n = 49) sea level Ballabhgarh areas and in rural high altitude areas of Leh, Ladakh in North India (n = 35). Our study revealed that the gut microbiome of Indian communities is dominated by Firmicutes followed by Bacteroidetes, Actinobateria and Proteobacteria. Although, 54 core bacterial genera were detected across the three distinct communities, the gut bacterial composition displayed specific signatures and was observed to be influenced by the topographical location and dietary intake of the individuals. The gut microbiome of individuals living in Leh was observed to be significantly similar with a high representation of Bacteroidetes and low abundance of Proteobacteria. In contrast, the gut microbiome of individuals living in Ballabhgarh areas harbored higher number of Firmicutes and Proteobacteria and is enriched with microbial xenobiotic degradation pathways. The rural community residing in sea level Ballabhgarh areas has unique microbiome characterized not only by a higher diversity, but also a higher degree of interindividual homogeneity.
Summary
Background
The increased risk of colorectal cancer in ulcerative colitis is well known. The risk of sporadic colorectal cancer in Asian populations is considered low and risk estimates of colorectal cancer related to ulcerative colitis from Asia vary. This meta-analysis is an Asian perspective on the risk of colorectal cancer related to ulcerative colitis.
Methods
We searched PubMed and Embase for terms related to colorectal cancer in ulcerative colitis from inception to July 1, 2016. The search for published articles was done by country for all countries in Asia. We included studies with information on the prevalence and cumulative risk of colorectal cancer at various timepoints. A random-effects meta-analysis was done to calculate the pooled prevalence as well as a cumulative risk at 10 years, 20 years, and 30 years of disease.
Findings
Our search identified 2575 articles; of which 44 were eligible for inclusion. Our analysis included a total of 31 287 patients with ulcerative colitis with a total of 293 reported colorectal cancers. Using pooled prevalence estimates from various studies, the overall prevalence was 0·85% (95% CI 0·65–1·04). The risks for colorectal cancer were 0·02% (95% CI 0·00–0·04) at 10 years, 4·81% (3·26–6·36) at 20 years, and 13·91% (7·09–20·72) at 30 years. Subgroup analysis by stratifying the studies according to region or period of the study did not reveal any significant differences.
Interpretation
We found the risk of colorectal cancer in Asian patients with ulcerative colitis was similar to recent estimates in Europe and North America. Adherence to screening is therefore necessary. Larger population-based, prospective studies are required for better estimates of the risk.
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