Occupational exposure and sarcoidosis: a case-control study in three countries.

Background: Preceding studies of environmental and occupational risk factors of sarcoidosis yielded inconsistent findings.

Aims: We aimed to ascertain the occupational risk factors for sarcoidosis in a case-control study.

Methods: A total of 237 sarcoidosis patients with a histologically confirmed diagnosis were matched with 474 controls for sex and age (median 49, interquartile range 37; 60 years) recruited from the university hospitals and outpatient centres in Belarus, Kazakhstan and the Russian Federation. Ever and cumulative (considering years and hours per week) exposure to 24 occupational factors were analysed using logistic regression.

Results: In the overall sample of 711 subjects, 50% were females and any occupational exposure was more prevalent in cases compared to controls (60% versus 40%, P < 0.001). Current daily smoking as opposed to ex-smoking was associated with the lower risk of the outcome. Adjusted for smoking, age, sex and a few other exposures, ever-exposure to hay in agriculture (odds ratio (OR) 3.64 (95% confidence interval (CI) 1.26; 10.50)), engine exhausts (OR 2.94 (95% CI 1.14; 7.54)) and printing equipment (OR 1.66 (95% 1.03; 2.68)) was associated with sarcoidosis. The effect was also positive for cumulative exposure to hay in agriculture (OR 2.02 (95% CI 1.00; 4.07)), stone dust (OR 1.07 (95% CI 1.01; 1.14)) and engine exhausts (OR 1.18 (95% CI 1.03; 1.38)) and was stronger in never-smokers and subjects 40 years and older.

Conclusions: Widespread occupational exposures may increase the risk of sarcoidosis, but further research is needed to elucidate the complex interplay of environmental and occupational factors in the epidemiology of sarcoidosis.