Systematic review: worldwide variation in the frequency of coeliac disease and changes over time

Summary Background Coeliac disease (CD), originally thought to be largely confined to Northern Europe and Australasia and uncommon in North America and the Middle East, is now recognised to be equally common in all these countries. It is still thought to be rare in the Orient and Sub‐Saharan Africa. Aim To assess geographical differences and time trends in the frequency of CD. Methods Medline and Embase searches were conducted on 10 November 2012, from 1946 and 1980 respectively, using the key words: coeliac disease or celiac disease + prevalence or incidence or frequency. Results There were significant intra‐ and inter‐country differences in the prevalence and incidence of CD. Only 24 ethnic Chinese and Japanese patients have been reported in the English literature. Of CD‐associated HLA DQ antigens, DQ2 occurs in 5–10% of Chinese and sub‐Saharan Africans, compared to 5–20% in Western Europe. DQ8 occurs in 5–10% of English, Tunisians and Iranians, but in