S76 Mendelian randomization study of cigarette smoking in idiopathic pulmonary fibrosis

Introduction and ObjectivesA cigarette smoking – idiopathic pulmonary fibrosis (IPF) association has been observed in several case-control studies. However, it is not known whether smoking causes IPF or if the observed association arises as a result of confounding (for example many studies have used population controls and may be vulnerable to selection bias).Mendelian randomization can offer an opportunity to investigate causality between cigarette smoking and IPF.MethodsGenetic instruments for lifetime smoking score[1] (taking into account smoking duration and heaviness) were obtained from a genome-wide association study (GWAS) performed in UK Biobank (462,690 individuals, European ancestry). We used variants that were significantly associated with smoking at p