Smoking, obesity and risk of sarcoidosis: A population-based nested case-control study

Background Smoking and obesity might alter the risk of sarcoidosis. However, the data remained inconclusive. Methods A cohort of Olmsted County, Minnesota residents diagnosed with sarcoidosis between January 1, 1976 and December 31, 2013 was identified based on individual medical record review. For each sarcoidosis subject, one sex and aged-matched control without sarcoidosis was randomly selected from the same underlying population. Medical records of cases and controls were reviewed for smoking status at index date and body mass index (BMI) within 1 year before to 3 months after index date. Results 345 incident cases of sarcoidosis and 345 controls were identified. The odds ratio of sarcoidosis comparing current smokers with never smokers adjusted for age and sex was 0.34 (95% confidence interval (CI), 0.23–0.50). The odds ratio of sarcoidosis comparing current smokers with never smokers and former smokers adjusted for age and sex was 0.38 (95% CI, 0.26–0.56). The odds ratio of sarcoidosis comparing overweight subjects (BMI ≥ 25 kg/m² but < 30 kg/m²) with subjects with normal/low BMI was 1.12 (95% CI, 0.72–1.75). The odds ratio of sarcoidosis comparing obese subjects (BMI ≥ 30 kg/m²) with subjects with normal/low BMI was 2.54 (95% CI, 1.58–4.06). The odds ratio of sarcoidosis comparing obese subjects with non-obese subjects was 2.38 (95% CI, 1.60–3.56). Conclusion In this population, current smokers have a lower risk of developing sarcoidosis while subjects with obesity have a higher risk of developing sarcoidosis.