Inflammatory bowel disease in India - Past, present and future

Area of Science:

• Gastroenterology and Epidemiology
• Inflammatory Bowel Disease Research
• South Asian Health Studies

Background:

• Rising incidence and prevalence of inflammatory bowel disease (IBD) in India, surpassing other Southeast Asian (SEA) nations.
• Distinct genetic underpinnings for IBD in Indian patients compared to Western populations, with an unclear role for the "hygiene hypothesis".
• Observed North-South epidemiological divide in India, with ulcerative colitis (UC) more prevalent in the North and Crohn's disease (CD) in the South.

Observation:

• IBD in second-generation Indian migrants to the West exhibits early onset and severity akin to Western cases.
• Migrants to SEA countries retain IBD characteristics of their country of origin.
• Clinical presentation in India aligns with other SEA countries regarding demographics, family history, smoking effects, disease location, and treatment modalities like aminosalicylates for CD, with lower biologic use and similar surgical rates.
• Specific differences include a higher incidence of inflammatory CD, less perianal disease, increased use of aminosalicylates and azathioprine, and lower current corticosteroid use.
• UC in India often presents with extensive disease but follows a generally benign clinical and histological course with good medical control and low rates of severe complications, cancer, or surgery.
• UC-related colorectal cancer development is unpredictable, challenging current screening protocols.
• A significant proportion of CD patients in India receive antituberculosis drugs, and many present with small intestinal bleeding due to aggressive inflammation.
• Current biomarkers lack sufficient diagnostic accuracy for both UC and CD.
• Pediatric IBD cases tend to be more severe than adult-onset IBD.

Findings:

• Genetic factors in Indian IBD differ from Western populations.
• IBD presentation and progression show variations based on geographic location and migration patterns.
• Ulcerative colitis in India has a milder course than in the West, but colorectal cancer risk is unpredictable.
• Crohn's disease often involves aggressive small intestinal inflammation and is sometimes treated with antituberculosis drugs.
• Diagnostic tools and biomarkers require significant improvement for accurate IBD assessment in India.

Implications:

• Urgent need for population-based studies to clarify IBD epidemiology and etiological factors in India.
• Development of novel biomarkers and advanced diagnostic techniques, including endoscopy, molecular pathology, and genetics, is crucial.
• Tailored diagnostic and treatment strategies are necessary, considering the unique characteristics of IBD in the Indian subcontinent.
• Re-evaluation of colorectal cancer screening protocols for UC patients in India may be warranted due to unpredictable disease behavior.