Table 1.

Summary of Different Phenotypes of Inflammatory Bowel Disease in the Asian and Western Population

Different phenotype	Asia	West
Incidence of IBD	Still low, but rapidly increasing.	High, but stable.
Prevalence of IBD	Rapidly increasing and their gap between Asia and West is narrowing.	Much higher.
Environmental and dietary factors
Brest feeding, physical activity	Both protective effect on IBD development in Asia and West.
Smoking	No association for the risk of CD.	Increased risk of CD.
Appendectomy	Inconsistent effect on the risk of UC (no association23 vs decreased risk24-26).	Decreased risk of UC.
Diet	Sugar, fat, meat, oil has increased risk of IBD. But, lower fiber has no association with the risk of IBD.	Sugar, fast food, red meat has increased risk of IBD, and lower fiber has increased risk of IBD.
	Daily tea and coffee have decreased risk of IBD.
UC/CD ratio	UC/CD ratio is high, but has been reduced.	UC/CD ratio is low.
Sex	Male predominance in both CD and UC, but it is significantly higher for CD and slightly higher for UC.	Female predominance for CD.
		No sex predominance for UC.
Age	Bimodal age distribution is noted in recent studies, but single peak is noted in the past studies.	Bimodal age distribution.
	Age at diagnosis is 5–10 years earlier for CD than that of UC in Asia and West.
Disease extent of UC	No significant difference for the disease extent of UC between Asia and West.
Disease location of CD	More L3 location and higher proportion of L4 for the disease location of CD.	More L2 location for the disease location of CD.
Disease behavior of CD	Disease behavior is more complicated with more perianal fistulas.	70%–80% of CD has B1 behavior.
Extraintestinal manifestation	Variable, but lower than those in West.	Variable.
Family aggregation	Lower frequency.	Higher frequency.

IBD, inflammatory bowel disease; CD, Crohn disease; UC, ulcerative colitis.