The incidence of autoimmune thyroid disease: a systematic review of the literature

Summary Objective To undertake a systematic review of literature published between 1980 and 2008 on the incidence of autoimmune thyroid disease. Design All relevant papers found through searches of Medline, EMBASE and ScienceDirect were critically appraised and an assessment was made of the reliability of the reported incidence data. Results The reported incidence of autoimmune hypothyroidism varied between 2·2/100 000/year (males) and 498·4/100 000/year (females) and for autoimmune hyperthyroidism, incidence ranged from 0·70/100 000/year (Black males) to 99/100 000/year (Caucasian females). Higher incidence rates were found in women compared to men for all types of autoimmune thyroid disease. The majority of studies included in the review investigated Caucasian populations mainly from Scandinavia, Spain, the UK and the USA. It is possible that nonautoimmune cases were included in the incidence rates reported here, which would give an overestimation in the incidence rates of autoimmune disease presented. Conclusion To our knowledge this is the most comprehensive systematic review of autoimmune thyroid disease conducted in the past two decades. Studies of incidence of autoimmune thyroid disease have only been conducted in a small number of mainly western countries. Our best estimates of the incidence of hypothyroidism is 350/100 000/year in women and 80/100 000/year in men; the incidence of hyperthyroidism is 80/100 000/year in women and 8/100 000/year in men.