Bell’s palsy and obesity, alcohol consumption and smoking: A nested case-control study using a national health screening cohort

The aim of this study was to investigate the association of body mass index (BMI), alcohol consumption, and smoking status with the occurrence of Bell’s palsy. The Korean National Health Insurance Service-Health Screening Cohort of a ≥ 40-year-old population from 2000–2003 was used. A total of 5,632 Bell’s palsy participants were matched with 22,528 control participants in terms of age, sex, income, region of residence, and past medical histories of hypertension, diabetes, and dyslipidemia. Bell’s palsy was classified by a history of ≥2 diagnoses with ICD-10 code (G510) and steroid treatment. BMI (kg/m 2 ) was classified as