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

Introduction: A recent study found that the prevalence of chronic obstructive pulmonary disease (COPD) is significantly higher among adults who began smoking cigarettes before (versus 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 secondhand smoke exposure, using data from U.S. adults aged 40+ years during Wave 5 (2018-2019) of the Population Assessment of Tobacco and Health Study.

Methods: Adults who had ever smoked cigarettes were asked at what age they began smoking fairly regularly. Multivariable Poisson regression assessed the risk of self-reported COPD diagnosis due to childhood smoking (<15 years), adjusting for current smoking, cigarette pack years or smoking duration, secondhand smoke exposure, and sociodemographic covariates.

Results: 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 (versus 15+) years had a higher prevalence of current smoking (45.9% versus 33.3%), longer smoking duration (mean 34.2 versus 27.3 years), greater cigarette pack years (mean 48.8 versus 30.8), and greater secondhand smoke exposure (p's<0.05). In multivariable analysis, the relative risk for COPD for smoking onset <15 (versus 15+) years of age was 1.27 (95% confidence interval=1.06, 1.51).

Conclusion: The increased risk of COPD due to childhood smoking was independent of cigarette pack years, smoking duration, secondhand smoke exposure, and current smoking. The findings give further evidence of increased COPD risk related to childhood smoking.