Epidemiology
Sarcoidosis most commonly affects young adults of both sexes, although studies have reported more cases in females. Incidence is highest for individuals younger than 40 and peaks in the age-group from 20 to 29 years; a second peak is observed for women over 50.
Sarcoidosis occurs throughout the world in all races with an average incidence of 16.5 per 100,000 in men and 19 per 100,000 in women. The disease is most prevalent in Northern European countries and the highest annual incidence of 60 per 100,000 is found in Sweden and Iceland. In the United Kingdom the prevalence is 16 in 100,000. In the United States, sarcoidosis is more common in people of African descent than Caucasians, with annual incidence reported as 35.5 and 10.9 per 100,000, respectively. Sarcoidosis is less commonly reported in South America, Spain, India, Canada, and the Philippines. There may be a higher susceptibility to sarcoidosis in those with coeliac disease. An association between the two disorders has been suggested.
The differing incidence across the world may be at least partially attributable to the lack of screening programs in certain regions of the world, and the overshadowing presence of other granulomatous diseases, such as tuberculosis, that may interfere with the diagnosis of sarcoidosis where they are prevalent. There may also be differences in the severity of the disease between people of different ethnicities. Several studies suggest the presentation in people of African origin may be more severe and disseminated than for Caucasians, who are more likely to have asymptomatic disease.
Manifestation appears to be slightly different according to race and sex. Erythema nodosum is far more common in men than in women and in Caucasians than in other races. In Japanese patients, ophthalmologic and cardiac involvement are more common than in other races.
Sarcoidosis is one of the few pulmonary diseases with a higher prevalence in nonsmokers.
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