Interaction of Cigarette Smoking and Polygenic Risk Score on Reduced Lung Function

This cohort study assesses the interaction of cigarette smoking and polygenic risk score in association with reduced lung function among participants in the UK Biobank cohort.
Key Points Question Does cigarette smoking interact with genetic risk on the percent of forced vital capacity exhaled in the first second (FEV1/FVC)? Findings In this UK Biobank cohort study of 319 730 UK citizens, FEV1/FVC was associated with polygenic risk score-by-smoking interactions, and smoking was detrimental across all categories of estimated genetic risk, although it was worse for those with the highest estimated genetic risks. For every reported 20 pack-years of smoking, individuals in the top decile compared with the bottom decile of genetic risk showed nearly twice the reduction in FEV1/FVC. Meaning These findings suggest that elucidating mechanisms for the interaction between smoking and genetic risk could yield greater insight into the chronic obstructive pulmonary disease pathogenesis.
Importance The risk of airflow limitation and chronic obstructive pulmonary disease (COPD) is influenced by combinations of cigarette smoking and genetic susceptibility, yet it remains unclear whether gene-by-smoking interactions are associated with quantitative measures of lung function. Objective To assess the interaction of cigarette smoking and polygenic risk score in association with reduced lung function. Design, Setting, and Participants This UK Biobank cohort study included UK citizens of European ancestry aged 40 to 69 years with genetic and spirometry data passing quality control metrics. Data was analyzed from July 2020 to March 2021. Exposures PRS of combined forced expiratory volume in 1 second (FEV1) and percent of forced vital capacity exhaled in the first second (FEV1/FVC), self-reported pack-years of smoking, ever- vs never-smoking status, and current- vs former- or never-smoking status. Main Outcomes and Measures FEV1/FVC was the primary outcome. Models were used to test for interactions with models, including the main effects of PRS, different smoking variables, and their cross-product terms. The association between pack-years of smoking and FEV1/FVC were compared for those in the highest vs lowest decile of estimated genetic risk for low lung function. Results We included 319 730 individuals, of whom 24 915 (8%) had moderate-to-severe COPD cases, and 44.4% were men. Participants had a mean (SD) age 56.5 of (8.02) years. The PRS and pack-years were significantly associated with lower FEV1/FVC (PRS: β, −0.03; 95% CI, −0.031 to −0.03; pack-years: β, −0.0064; 95% CI, −0.0064 to −0.0063) and the interaction term (β, −0.0028; 95% CI, −0.0029 to −0.0026). A stepwise increment in estimated effect sizes for these interaction terms was observed per 10 pack-years of smoking exposure. The interaction of PRS with 11 to 20, 31 to 40, and more than 50 pack-years categories were β (interaction) −0.0038 (95% CI, −0.0046 to −0.0031); −0.013 (95% CI, −0.014 to −0.012); and −0.017 (95% CI, −0.019 to −0.016), respectively. There was evidence of significant interaction between PRS with ever- or never- smoking status (β, interaction; −0.0064; 95% CI, −0.0068 to −0.0060) and current or not-current smoking (β, interaction; −0.0091; 95% CI, −0.0097 to −0.0084). For any given level of pack-years of smoking exposure, FEV1/FVC was significantly lower for individuals in the tenth decile (ie, highest risk) than the first decile (ie, lowest risk) of genetic risk. For every 20 pack-years of smoking, those in the tenth decile compared with the first decile of genetic risk showed nearly a 2-fold reduction in FEV1/FVC. Conclusions and Relevance COPD is characterized by diminished lung function, and our analyses suggest there is substantial interaction between genome-wide PRS and smoking exposures. While smoking was associated with decreased lung function across all genetic risk categories, the associations were strongest in individuals with higher estimated genetic risk.