Epidemiology of sarcoidosis in northern Spain, 1999-2019: A population-based study

Background: The incidence of sarcoidosis varies widely worldwide. The aim of this study was to estimate the incidence of sarcoidosis in a population-based cohort from northern Spain. Methods: Patients diagnosed with sarcoidosis at Marque acute accent s de Valdecilla University Hospital, corresponding to the central Cantabria that encompasses Santander city and the surroundings, between January 1999 and December 2019were assessed. The diagnosis of sarcoidosis was established according to ATS/ERS/WASOG criteria as follows: compatible clinical and radiological presentation, histopathologic confirmation, and exclusion of other granulomatous diseases. Demographic and clinical data were collected. The incidence of sarcoidosis between 1999-2019 was estimated by sex, age, and year of diagnosis. Results: A total of 234 patients were included, with a male/female ratio of 0.81. The mean age of the cohort at diagnosis was 48.43 +/- 14.83 years and 129 (55.1%) were women. Incidence during the period of study was 3.58 per 100,000 populations (95% confidence interval: 3.13 - 4.07). No gender predominance was observed. An increase in age at diagnosis over time was found in the linear regression analysis. Thoracic affection was found in 180 patients (76.9%). Most common extra-thoracic areas affected were skin (34.2%), joints (30.8%) and eyes (15.4%). Conclusions: The incidence of sarcoidosis estimated in this study was similar to that of other Mediterranean countries. No gender predominance was observed. Consistent with previous studies, male presented an incidence peak 10 years earlier than female. A second peak between ages 60-69 years was identified in both sexes.