A population-based matched cohort study of sarcoidosis incidence, prevalence, and all-cause mortality. The HUNT study

Although sarcoidosis is considered a benign disease, epidemiologic studies have shown increased mortality rates. We aimed to investigate sarcoidosis incidence, prevalence, mortality, and possible time trends in Nord-Trondelag, Norway. Sarcoidosis incidence and prevalence were estimated among participants in the first three surveys of the HUNT Study (106`000 participants). 10% of cases were included through x-ray screening (HUNT 1), the remaining were identified from health records. For mortality analysis, we conducted a matched cohort study of 310 cases diagnosed after participation in HUNT 1 (1984-86), HUNT 2 (1995-97) or HUNT 3 (2006-08) with follow-up until April 2023. Cases were matched 1:4 on age and sex. Crude and adjusted hazard-ratios (HR) and 95% confidence intervals (95% CI) for all-cause mortality were analysed using Cox regression analyses. The mean follow-up time was 18 years. From HUNT 1 to HUNT 3, age-standardized incidence increased from 12.6 (95% CI 9.6-14.4) to 19.4 (95% CI 14.7-22.5) per 100`000/year, while period prevalence increased from 90 (95% CI 69-111) to 141 (95% CI 108-174) per 100`000. The largest increase in incidence and prevalence was seen in non-Lofgren syndrome (nLS) and men. Patients with nLS had more than twice the mortality compared to matched controls, HR 2.4 (1.8, 3.1), and corresponding comparison by sex showed higher mortality in men, HR 2.1 (1.3, 3.4). Mortality was not increased in Lofgren syndrome (LS). Sarcoidosis incidence and prevalence are increasing, driven by nLS and males. Mortality in nLS is increased and the mechanisms need to be further addressed, particularly in men who seem to have a worse prognosis.