Smoking before age 15 years raises COPD risk in adulthood regardless of smoking factors
Key takeaways:
- Factors included smoking status, cigarette pack-years/smoking length, secondhand smoke exposure and more.
- COPD was more frequent in the cohort who started smoking during childhood vs. at age 15 years or later.
The adjusted risk for COPD was elevated among adults who identified as regular cigarette smokers before age 15 years, according to results published in Chronic Obstructive Pulmonary Diseases: Journal of the COPD Foundation.
Notably, adjustment was for multiple smoking factors, including smoking status, cigarette pack-years, smoking duration, secondhand smoke exposure and sociodemographic covariates, according to researchers.
“Even though childhood cigarette smoking rates are declining, it is crucial to continue to support ongoing guidelines and efforts aimed at reducing childhood smoking,” Laura M. Paulin, MD, MHS, pulmonologist with Dartmouth Health, told Healio. “Our research reinforces that the developing lungs of children are particularly vulnerable to cigarette smoking, and delaying and avoiding cigarette initiation completely has the potential to markedly decrease COPD risk decades later.”
In this study, Paulin and colleagues assessed 10,126 adults (53.4% women; 80.2% white) aged 40 years or older from the Population Assessment of Tobacco and Health Study in 2018 to 2019 to determine how COPD risk is linked to age of regular smoking initiation (< 15 years old vs. ≥ 15 years old).
Researchers used multivariable analysis that accounted for smoking status, cigarette pack-years/smoking duration, secondhand smoke exposure and sociodemographic covariates to find this relationship.
As Healio previously reported, this research group found that in adulthood, the risk for COPD rose with regular cigarette smoking starting before age 15 years in a study published in American Journal of Respiratory and Critical Care Medicine. Notably, this study accounted for the above factors except secondhand smoke exposure.
Nearly half of the total cohort never smoked (47.2%), and researchers observed more former smokers than current smokers (35.3% vs. 17.5%).
A self-reported COPD diagnosis was noted for 13.4% of adults, and this diagnosis was reported more frequently in the cohort who started smoking regularly before age 15 years vs. the cohort who started smoking regularly at age 15 years or older and the cohort who never smoked (29% vs. 21.1% vs. 7.5%).
Researchers observed that 45.9% of the group who started smoking regularly before age 15 years were current smokers, which was significantly larger than the 33.3% observed in the group who started smoking regularly at age 15 years or older.
Compared with the cohort of regular smokers at age 15 years or older, the study noted more mean pack-years in the cohort of regular smokers before age 15 years (48.8 vs. 30.8).
In terms of smoking duration, the mean length of time was 34.2 years for those reporting early-onset/childhood smoking, whereas this length of time was shorter for those reporting later-onset smoking (27.3 years).
Lastly, secondhand smoke exposure based on the past 7 days was higher among the regular smokers before vs. at 15 years or older (10.1 hours vs. 5.7 hours), according to the study.
After accounting for these measures of cigarette use, researchers found that childhood cigarette smoking raised the risk for COPD (adjusted RR = 1.27; 95% CI, 1.06-1.51).
“It is remarkable that the association between early age of starting cigarette smoking with COPD prevalence remained significant, even when accounting for multiple measures of cigarette use throughout the lifetime, well beyond the time of cigarette onset,” Paulin told Healio.
In sensitivity analysis, childhood smoking continued to heighten the risk for COPD after using smoking duration as a dichotomous measure instead of pack-years, according to the study.
“The increased risk of COPD due to childhood smoking was independent of lifetime cigarette pack-years, smoking duration, secondhand smoke exposure and current smoking,” Paulin told Healio. “These results highlight that injury during adolescent lung development can have lifelong impacts.”
The study further highlighted links between a heightened risk for COPD and three separate factors: current vs. never/former smoking (aRR = 1.37; 95% CI, 1.19-1.59), cigarette pack-years (aRR = 1.02 per 10 pack-years; 95% CI, 1.01-1.03) and secondhand smoke exposure in the past 7 days (aRR = 1.06 per 5 hours; 95% CI, 1.02-1.04).
“Ideally, future longitudinal studies will take into account additional inhalational exposures that are known to contribute to respiratory disease, including comprehensive occupational exposure history, as well as past and ongoing air pollution exposures, including those related to indoor heating and cooking,” Paulin told Healio.
“It will be valuable to develop similar studies investigating the relationship between age of onset of e-cigarette use and adult lung disease, including COPD,” Paulin added. “Given that e-cigarettes have gained popularity in the last decade or so, it will be several more years until the long-term health consequences of these products are observed.”
Reference:
- Childhood smoking increases a person’s risk of developing COPD. https://www.copdfoundation.org/About-Us/Press-Room/Press-Releases/Article/2074/Childhood-smoking-increases-a-person-s-risk-of-developing-COPD.aspx. Published Jan. 7, 2025. Accessed Jan. 7, 2025.
Perspective
Back to Top
The findings of this study are not surprising, as the field of COPD research has increasingly shifted toward redefining the disease. Evidence now supports that pre- and peri-natal factors, along with childhood exposures, influence lung growth and contribute to the early development of fixed airflow limitation. However, the study’s robust replication using nationally representative data, alongside adjustments for secondhand smoke exposure, adds significant value by reinforcing the long-term risks associated with early smoking initiation.
In my clinical experience, patients with a history of early smoking show greater lung damage and a higher prevalence of chronic respiratory conditions. The study’s emphasis on the critical window of lung development during adolescence aligns closely with my observations, where adolescent smoking exposure is a major contributor to the development of fixed airflow limitation.
These findings emphasize the need to prevent early smoking initiation as part of a comprehensive public health approach. Physicians should intensify efforts to educate youth and families about the risks of smoking during critical lung development periods. Advocating for policies such as Tobacco 21 legislation and implementing community-based interventions can help delay or prevent smoking initiation. Moreover, doctors should ensure thorough assessments of smoking history, including first- and secondhand exposure, during routine patient evaluations — an area that is often overlooked. Early screening tools, such as pulmonary function tests, and prioritizing smoking cessation programs for individuals with childhood smoking exposure could further enhance patient care.
Future research should integrate objective measures such as spirometry to validate self-reported COPD diagnoses and assess the physiological impact of early smoking initiation more accurately. Longitudinal studies examining cumulative secondhand smoke exposure during childhood and prenatal exposure are also needed. Investigating genetic and epigenetic mechanisms that predispose individuals to greater vulnerability from early smoking exposures could uncover pathways for targeted therapies, particularly for individuals with a genetic predisposition to early COPD.
This study reinforces the evolving understanding of COPD as more than just a self-inflicted disease of elderly smokers. It highlights the potential for COPD to manifest earlier in life and the importance of preventing early risk factor exposures. However, limitations such as reliance on self-reported data and incomplete accounting for lifetime cumulative secondhand smoke exposure need to be addressed. Incorporating detailed, longitudinal assessments of environmental and genetic factors could improve the robustness of future studies. Additionally, this research should inspire public health campaigns targeting youth to prevent smoking initiation, potentially altering the trajectory of COPD incidence on a larger scale.
Collapse
Read more about