Seasonal variation in incidence of sarcoidosis: a population-based study, 1976-2013

Studies of seasonal patterns of incidence of sarcoidosis may provide a better understanding of potential environmental triggers of the disease. In this study, Olmsted County, Minnesota residents who were diagnosed with sarcoidosis between 1976 and 2013 were identified based on individual medical record review. The seasonal variation of incident sarcoidosis was then calculated. The age-adjusted and sex-adjusted incidence rate of sarcoidosis was lower in autumn (2.0/100 000; 95% CI 1.5 to 2.5) compared with winter (3.2/100 000; 95% CI 2.6 to 3.8), spring (2.8/100 000; 95% CI 2.2 to 3.4) and summer (2.9/100 000; 95% CI 2.2 to 3.5, p=0.024). Subgroup analysis per decade consistently showed lower incidence of sarcoidosis in autumn.