Prevalence, incidence, and mortality associated with sarcoidosis over three decades in the HUNT Study in Norway

The incidence and prevalence of sarcoidosis vary globally, with the highest estimates in Scandinavia. Since there are no recent data from Norway, we aimed to investigate the prevalence, incidence and mortality of sarcoidosis over three decades among participants in the population-based HUNT Study. The study population included participants in the first three surveys of the HUNT Study (HUNT1,1984-86; HUNT2,1995-97 and HUNT3, 2006-08). We identified 365 participants with sarcoidosis. Approximately 10 % of sarcoidosis patients were identified by x-ray screening in HUNT1, the remaining by linkage to hospital records. We randomly selected four age, sex and survey-matched participants without sarcoidosis for each of the 310 participants with incident sarcoidosis and followed these from diagnosis until death or end of follow-up in 2023. We used Cox regression to estimate adjusted hazard ratios (HRs) with 95 % confidence intervals (CIs) of death from all-causes. From 1984 to 2018, annual prevalence increased from 0.54 (95 % CI 0.41, 0.72) to 1.34 (95 % CI 1.08, 1.64) percent, while incidence rate increased from 12.1 (95 % CI 9.5, 14.7) to 18.7 (95 % CI 13.4, 24.0) per 100 000/year. The largest increase was seen in non-Lofgren syndrome (nLS). People with nLS had more than twice the mortality compared to people without sarcoidosis (HR 2.4; 95 % CI, 1.9, 3.1). There was no clear association between Lofgren syndrome and overall mortality. Sarcoidosis prevalence and incidence appeared to increase, particularly for nLS. Mechanisms leading to increased mortality in nLS needs to be further addressed.