Seasonality of the onset of symptoms, Tuberculin test anergy and Kveim positive reaction in a large cohort of patients with sarcoidosis

Background and objectives: Sarcoidosis is a systemic granulomatous disease of unknown aetiology and pathogenesis. This study evaluated the seasonal variation in the onset of symptoms, Tuberculin anergy and Kveim positive reaction in a cohort of 492 patients with sarcoidosis and in a subgroup of 248 patients with known Kveim test responses. Methods: The medical records of 492 patients with sarcoidosis were retrospectively reviewed. Roger's test for cyclic variation was used to assess the statistical significance of the observed seasonal variation. Results: For all sarcoidosis patients (n = 492) the onset of symptoms was most frequent in spring (61.8%) and least frequent in summer (31.7%) (P < 0.001). For patients with Tuberculin anergy (n = 364) the onset of symptoms was most frequent in spring and least frequent in autumn (P < 0.001); there was no seasonal variation among Tuberculin positive patients (n = 128). Of those patients with a Kveim test result (n = 248), the onset of symptoms was most frequent in spring and least frequent in summer (P < 0.001); there was no seasonal variation for patients with a negative Kveim results (n = 50 patients). Conclusions: The onset of the symptoms was most frequent in spring and least frequent in the second half of the year (summer or autumn) in patients with sarcoidosis, Tuberculin anergy and a positive Kveim reaction. The significance of this finding in relation to aetiology and clinical utility needs to be further assessed.