Association of smoking, lung function and COPD in COVID-19 risk: a two-step Mendelian randomization study.

BACKGROUND AND AIMS: Smoking increases the risk of severe COVID-19, but whether lung function or chronic obstructive pulmonary disease (COPD) mediate the underlying associations is unclear. We conducted the largest Mendelian randomization study to date, to our knowledge, to address these questions. DESIGN: Mendelian randomization study using summary statistics from genome-wide association studies (GWAS), FinnGen and UK Biobank. The main analysis was the inverse variance weighted method, and we included a range of sensitivity analyses to assess the robustness of the findings. SETTING: GWAS which included international consortia, FinnGen and UK Biobank. PARTICIPANTS: The sample size ranged from 193 638 to 2 586 691. MEASUREMENTS: Genetic determinants of life-time smoking index, lung function [e.g. forced expiratory volume in 1 sec (FEV1 )], chronic obstructive pulmonary disease (COPD) and different severities of COID-19. RESULTS: Smoking increased the risk of COVID-19 compared with population controls for overall COVID-19 [odds ratio (OR) = 1.19 per standard deviation (SD) of life-time smoking index, 95% confidence interval (CI) = 1.11-1.27], hospitalized COVID-19 (OR = 1.67, 95% CI = 1.42-1.97) or severe COVID-19 (OR = 1.48, 95% CI = 1.10-1.98), with directionally consistent effects from sensitivity analyses. Lung function and COPD liability did not appear to mediate these associations. CONCLUSION: There is genetic evidence that smoking probably increases the risk of severe COVID-19 and possibly also milder forms of COVID-19. Decreased lung function and increased risk of chronic obstructive pulmonary disease do not seem to mediate the effect of smoking on COVID-19 risk.

Parental Knowledge, Attitude, and Practice on Tobacco Use, Smoking Cessation, and Children's Environmental Tobacco Smoke Exposure.

Background: Environmental tobacco smoke (ETS) exposure in children ranks one of the major public health problems in our time. Poor parental knowledge, attitude, and practice (KAP) on ETS often contribute to worse exposure of the kids. Thus, we aimed to document parental KAP regarding tobacco use, smoking cessation and children's ETS exposure, and to analyse how knowledge and attitude relate to practice. Methods: Self-administered KAP questionnaires were distributed to smoking parents recruited from the pediatric unit at the Prince of Wales Hospital, which provides pediatric service to a population of 1.2 million in Hong Kong. The 60-item questionnaire had a range of 0-38 for knowledge, 0-44 for attitude, and 0-40 for practice. Descriptive analyses were performed for KAP response, regression analyses were performed for the exploration of associations and identification of predictive indicators. Results: 145 smoking parents (mean age: 38.0 ± 6.7 yrs.; male: 85.5%) were included. Less than half (39.3%) of them reported a smoke-free policy at home. Among those parents who had private cars, less than half (45.2%) of them had smoke-free policy in their car that they never smoked in the car. Only 25.5% of the participants correctly answered ≥70% of the knowledge questions, and 11.8 % of the participants gave favorable responses to ≥70% of the attitude questions. The total knowledge and the total attitudes score were positively associated (r = 0.49, 95% CI: 0.35-0.79, p < 0.001), yet they were only modestly correlated with parental practice on children's ETS exposure. By multivariate regressions, potential predictive factors for more favorable parental KAP included higher household income, lower parental nicotine dependence level and breastfeeding practice. Conclusions: Parental KAP related to tobacco use and children's ETS exposure needs improvement to address the significant gap between recommended and actual practice. The weak association between knowledge and practice suggested that parental education alone is not adequate to combat ETS exposure in children.