Modifiable lifestyle risk factors for sarcoidosis: a nested case–control study

OBJECTIVE: We aimed to investigate whether obesity, tobacco use, alcohol consumption and physical inactivity are associated with sarcoidosis risk. METHODS: We conducted a matched case–control study nested within the Northern Sweden Health and Disease Study. Incident sarcoidosis cases (n=165) were identified via medical records and matched to controls (n=660) on sub-cohort, sex, birth and questionnaire date (1:4). Data on lifestyle factors were obtained through questionnaires, and physical measurements of height, weight and waist were collected prior to sarcoidosis diagnosis. Conditional logistic regression estimated adjusted odds ratios with 95% confidence intervals (aOR; 95% CI). RESULTS: Compared with never-smoking, current smoking was associated with lower sarcoidosis odds (aOR 0.48; 95% CI 0.32–0.71), and former smoking with higher odds (aOR 1.33; 95% CI 0.98–1.81). Snus use was not associated with sarcoidosis. There was an increased odds of sarcoidosis associated with obesity (aOR 1.34; 95% CI 0.94–1.92) but not with overweight (aOR 0.99; 95% CI 0.76–1.30). Compared with those who were physically inactive, those who were active had a 25% higher odds of sarcoidosis (aOR 1.25; 95% CI 0.91–1.72). No association was found with moderate alcohol consumption (aOR 0.95; 95% CI 0.56–1.62). All results were similar when cases diagnosed within 5 years after exposure assessment were excluded, except the aOR for former smoking decreased to 1.1. CONCLUSION: We observed a reduced sarcoidosis risk associated with smoking, which cannot be fully explained by early symptoms of sarcoidosis influencing smoking habits. Results indicate an increased risk associated with obesity, but not overweight, and being physically active.