A new study finds that transitioning from conventional cigarettes to e-cigarettes could improve respiratory health, though further research is needed to understand long-term impacts.
Study: Functionally important respiratory symptoms and continued cigarette use versus e-cigarette switching: population assessment of tobacco and health study waves 2-6. Image Credit: Parkin Srihawong/Shutterstock.com
The use of e-cigarettes (vapes, EC) is often promoted as a helpful tool for quitting conventional cigarette (CC) smoking. Additionally, it is suggested that switching to e-cigarettes could reduce smoking-related respiratory symptoms. A recent study published in The Lancet tested the hypothesis that these symptoms might completely subside if CC users fully transitioned to using ECs.
Respiratory symptoms and smoking
Smoking is linked to respiratory symptoms that can lead to chronic lung damage, most commonly manifesting as chronic obstructive pulmonary disease (COPD) or chronic bronchitis/emphysema. These conditions often cause intermittent symptom worsening, reduced physical activity, increased hospitalization risk, and loss of income.
In young adults, respiratory symptoms are predictive of lung function, measured by forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC). However, many smokers cannot or will not quit, despite the potential for symptom improvement. This raises the question of whether switching to e-cigarettes (ECs) might reduce symptom severity by lowering exposure to tobacco smoke.
Previous research comparing dual users of conventional cigarettes (CCs) and ECs to exclusive users of either product shows that EC-only users have a lower risk of respiratory symptoms than CC users. However, EC users still face a higher risk of such symptoms compared to non-smokers. Since CC and EC use often overlap, it is challenging to isolate their individual effects on respiratory health.
Notably, current CC users—those who may benefit most from switching to ECs—rarely make a complete transition, maintaining their exposure to CC-related harm. Additionally, the risks and benefits of ECs are not fully understood, despite their widespread use among adolescents and their potential for high nicotine addiction and negative effects on neurological and cognitive health.
This study aimed to assess the impact of EC use on respiratory symptoms among current CC users, comparing outcomes for those who switched entirely to ECs, those who quit tobacco completely, and those who continued using CCs.
About the study
The data for this study were drawn from waves 2–6 (2014–2021) of the Population Assessment of Tobacco and Health (PATH) Study, a cohort study involving 5,653 American adults aged 18 or older who did not have chronic lung disease at baseline.
Participants with pre-existing lung conditions, such as COPD, chronic bronchitis, or chronic emphysema, were excluded. Researchers compiled data from two successive waves for each dataset, resulting in 14,947 observations from cigarette smokers.
The study examined the relationship between respiratory symptoms affecting lung function and continued use of conventional cigarettes (CC) versus switching exclusively to e-cigarettes (EC).
To assess respiratory health, a wheezing/nighttime cough index was used to categorize participants into two groups: those with scores of 2 or less (indicating better respiratory function) and those with scores of 3 or more (indicating worse respiratory function).
Risk factors
The symptom burden was affected by factors such as age, race, education, and comorbidities like obesity, asthma, heart disease, diabetes, and cancer. The use of cannabis over the last 30 days and a higher cigarette use habit, as well as second-hand smoke exposure, were other risk factors.
While 86.7% of people continued to use CCs, 3.7% switched completely to ECs, and 9.6% quit completely at follow-up.
Low symptom burden
In the class of individuals with index scores less than 2, 11% quit smoking completely, while 3.5% switched completely to ECs. Among those who quit, 10% had worsening of their symptoms (from index scores <2 to 2 or higher) on follow-up.
This was identical to the 10% of CC-to-EC users but less than the 15% of continued CC users, who experienced symptom worsening.
In this class, the risk of symptom exacerbation was reduced by 31% and 27% among those who switched to ECs and those who quit smoking, respectively, after adjusting for other risk factors.
High Symptom Burden
Among participants with baseline index scores of 2 or more, only 2.8% of conventional cigarette (CC) users switched entirely to e-cigarettes (ECs), while 6.7% quit smoking altogether. Functional respiratory symptom improvement (a decrease in index scores from 2 or higher to less than 2) was observed in 27.7% of those who continued smoking CCs, compared to 45.8% of those who switched to ECs and 42.1% of those who quit smoking entirely.
The likelihood of improvement was 31% higher for CC-to-EC switchers and 36% higher for those who quit smoking, compared to those who continued CC use.
Dual Use vs. EC-Only Use
Approximately 4.5% of CC users transitioned to dual use of CCs and ECs, but this did not lead to significant improvement in index scores compared to continued CC use.
In contrast, EC-only users had a 40% lower risk of symptom worsening compared to dual users, though the likelihood of symptom improvement was not significantly different.
Higher Symptom Threshold
When an index score of 3 was used as the cutoff for symptom burden, the strength of associations for both symptom worsening and improvement weakened by 17% and approximately 33%, respectively.
This suggests that the findings are less robust when assessing individuals with more severe symptoms.
Conclusions
The findings indicate that switching from CCs to ECs offers immediate or short-term benefits similar to quitting smoking entirely. This could provide valuable insights for smokers who struggle to quit and may find switching to ECs a viable option for improving respiratory health. This perspective is rarely emphasized in existing literature.
The study, however, was unable to assess changes in index scores for participants with the highest symptom burden due to missing data. These individuals may experience less improvement from switching to ECs due to irreversible pathological lung changes.
Further research is needed to validate these results and explore the long-term health implications of switching to ECs. Such studies could help determine whether ECs represent a lower-harm option for smokers with respiratory symptoms who cannot quit conventional cigarettes.
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