Environmental risk factors in inflammatory bowel disease: a population-based case-control study in Asia-Pacific

TLDR

Inflammatory bowel disease incidence is rising in Asia, underscoring the need to understand environmental risk factors. This study prospectively examined environmental exposures preceding IBD onset in an Asia‑Pacific population‑based case‑control design. Researchers recruited 442 incident IBD cases (186 Crohn’s disease, 256 ulcerative colitis, 374 Asians) and 940 matched controls from eight Asian and Australian countries, collected questionnaire data at diagnosis, and applied unconditional logistic regression to estimate adjusted odds ratios. Multivariate analysis showed that prolonged breastfeeding, antibiotic use, dog ownership, daily tea consumption, and physical activity lowered Crohn’s disease risk, while similar factors plus hot‑water tap and flush toilet use protected against ulcerative colitis, whereas ex‑smoking increased UC risk, highlighting the role of early life immunological, hygiene, and dietary exposures in IBD development.

Abstract

<h3>Objective</h3> The rising incidence of inflammatory bowel disease in Asia supports the importance of environmental risk factors in disease aetiology. This prospective population-based case-control study in Asia-Pacific examined risk factors prior to patients developing IBD. <h3>Design</h3> 442 incident cases (186 Crohn9s disease (CD); 256 UC; 374 Asians) diagnosed between 2011 and 2013 from eight countries in Asia and Australia and 940 controls (frequency-matched by sex, age and geographical location; 789 Asians) completed an environmental factor questionnaire at diagnosis. Unconditional logistic regression models were used to estimate adjusted ORs (aOR) and 95% CIs. <h3>Results</h3> In multivariate model, being breast fed &gt;12 months (aOR 0.10; 95% CI 0.04 to 0.30), antibiotic use (aOR 0.19; 0.07 to 0.52), having dogs (aOR 0.54; 0.35 to 0.83), daily tea consumption (aOR 0.62; 0.43 to 0.91) and daily physical activity (aOR 0.58; 0.35 to 0.96) decreased the odds for CD in Asians. In UC, being breast fed &gt;12 months (aOR 0.16; 0.08 to 0.31), antibiotic use (aOR 0.48; 0.27 to 0.87), daily tea (aOR 0.63; 0.46 to 0.86) or coffee consumption (aOR 0.51; 0.36 to 0.72), presence of hot water tap (aOR 0.65; 0.46 to 0.91) and flush toilet in childhood (aOR 0.71; 0.51 to 0.98) were protective for UC development whereas ex-smoking (aOR 2.02; 1.22 to 3.35) increased the risk of UC. <h3>Conclusions</h3> This first population-based study of IBD risk factors in Asia-Pacific supports the importance of childhood immunological, hygiene and dietary factors in the development of IBD, suggesting that markers of altered intestinal microbiota may modulate risk of IBD later in life.