Some information concerning the epidemiology of sarcoidosis is given below:
- around 3000 new cases are recognized each year in the UK (1)
- women more commonly affected than men (2)
- incidence and prevalence varies widely between countries (10/100,000 to over 100/100,000) most likely due to the differences in predisposing HLA alleles and other genetic factors, environmental exposures and surveillance methods (3)
- in USA annual age adjusted incidence for white Americans was 10.9 per 100 000 while for African-Americans it was 35.5 per 100 000population (3)
- highest incidence in Europe is reported in Sweden with 24 cases per 100,000 (2)
- the annual incidence in Japanese people ranges from 1 to 2 cases per 100,000 (3)
- a bimodal incidence has been reported in Scandinavia and in Japan with the first peak between 20 and 40 years of age and a second peak in females over the age of 50 years (2)
- uncommon in patients less than 15 years old (1/100,000) and exceptional before the age of 4 years (0.06/100,000) (4)
In the USA sarcoidosis is more common in African Americans. The reported ratio of African American to Caucasian patients with sarcoidosis in the United States ranges from 10:1 to 17:1. In African Americans:
- life time risk has been estimated to be 2.4% (for caucasians it was 0.85%) (4)
- the peak in icidence occurs later in life - in the fourth decade in both men and women (3)
- more commonly affects skin, joints and eyes
- features are more florid than in caucasians
- more likely to be chronic and fatal (3)
In addition to the differences in incidence across ethnicities, a marked phenotypic difference has also been reported e.g. - Lo¨ fgren’s syndrome commonly seen in northern European countries is very rare in people of African or Japanese origin (2).
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