Childhood Cigarette Smoking and Risk of COPD in Older United States Adults: A Nationally Representative Replication Study.

A recent study found that the prevalence of COPD is significantly higher among adults who began smoking cigarettes before (vs after) 15 years of age, independent of current smoking, cigarette pack-years, and smoking duration. The current analysis went a step further to also account for second-hand smoke exposure, using data from U.S. adults aged 40+ years during Wave 5 (2018-2019) of the Population Assessment of Tobacco and Health (PATH) Study. Adults who had ever smoked cigarettes were asked at what age they began smoking fairly regularly. Multivariable Poisson regression assessed risk of self-reported COPD diagnosis due to childhood smoking (<15 years), adjusting for current smoking, cigarette pack-years or smoking duration, second-hand smoke exposure, and sociodemographic covariates. Overall, 13.4% reported that they had COPD. COPD prevalence was 7.5% for adults who never smoked compared to 29.0% and 21.1% for smoking onset at age <15 and 15+ years, respectively. Adults who initiated smoking at <15 (vs 15+) years had higher prevalence of current smoking (45.9% vs 33.3%), longer smoking duration (mean 34.2 vs 27.3 years), greater cigarette pack-years (mean 48.8 vs 30.8), and greater second-hand smoke exposure (p's<0.05). In multivariable analysis, the relative risk for COPD for smoking onset <15 (vs 15+) years of age was 1.27 (95% confidence interval [CI]=1.06, 1.51). The increased risk of COPD due to childhood smoking was independent of cigarette pack-years, smoking duration, second-hand smoke exposure, and current smoking. Findings give further evidence of increased COPD risk related to childhood smoking.