Sarcoidosis in first- and second-generation immigrants: a cohort study of all adults 18 years of age and older in Sweden

Background There is a lack of studies on sarcoidosis among immigrants, which is of interest as there may be genetic and environmental characteristics affecting immigrants from certain countries. We aimed to study hazard ratios (HRs) of sarcoidosis in first- and second-generation immigrants, comparing them with native Swedes in the total adult Swedish population.Methods We conducted a nationwide study of individuals >= 18 y of age. Sarcoidosis was defined as at least two registered diagnoses in the National Patient Register between 1 January 1998 and 31 December 2018. Cox regression analysis was used to estimate HRs with 99% confidence intervals (CIs) of first registration of sarcoidosis in first- and second-generation immigrants compared with native Swedes. The Cox regression models were stratified by sex and adjusted for age, comorbidities and sociodemographic characteristics.Results In total, 6 175 251 were included in the first-generation study, with 12 617 cases of sarcoidosis, and 4 585 529 in the second-generation study, with 12 126 cases. The overall sarcoidosis risk was lower in foreign-born men (fully adjusted HR 0.63 [99% CI 0.57 to 0.69]) but not in foreign-born women (fully adjusted HR 0.98 [99% CI 0.90 to 1.06]). The overall risk was slightly lower in second-generation immigrants (HR 0.82 [99% CI 0.78 to 0.88]). Women from Asia exhibited a higher risk (HR 1.25 [99% CI 1.02 to 1.53)], while a potential trend was observed among women from Africa (HR 1.47 [99% CI 0.99 to 2.19]).Conclusions Sarcoidosis risk was lower in foreign-born men but not in women and also lower in second-generation immigrants.