medwireNews: The use of use of electronic (e)-cigarettes by late adolescents and young adults can be linked to the presence of respiratory symptoms, show the results of a large, prospective analysis performed in the USA.
The adjusted odd ratios (ORs) for experiencing wheeze, shortness of breath, and bronchitic symptoms – a daily cough for 3 consecutive months or a diagnosis of bronchitis in the past 12 months – were significantly higher among individuals who had used an e-cigarette device within the past 30 days than never users, at 1.81, 1.78, and 2.06, respectively.
The associations remained significant when individual tobacco and cannabis use, and exposure to secondhand e-cigarettes, smoking, and cannabis use were taken into consideration, with respective ORs of 1.41, 1.48, and 1.55.
“This study contributes to emerging evidence from human and toxicological studies that e-cigarettes cause respiratory symptoms that warrant consideration in regulation of e-cigarettes,” Rob McConnell (University of Southern California Keck School of Medicine, Los Angeles, USA) and associates write in Thorax.
They explain: “Components of the e-cigarette aerosol, including volatile aldehydes in flavourings, and oxidant metals, have known lung toxicity.” And e-cigarettes deliver these chemicals as very fine and ultrafine sprays, which means that they can reach the distal airways and alveoli, the researchers add, thereby “making the lung a target organ for injury and increasing risk for adverse respiratory health effects.”
The suggestion that e-cigarettes may cause respiratory symptoms is not new but there have been few prospective evaluations conducted to date that control for the use of cannabis and combustible cigarettes, say the researchers.
They used data from self-report questionnaires that had been completed in four waves in 2014, 2015, 2017, and 2018 as part of the Southern California Children’s Health Study.
The first survey was completed by 2097 individuals who were in the 11th or 12th grade of high school (mean age 17.3 years) at the time, with the second, third, and fourth follow-up surveys being completed by a respective 77%, 72%, and 78% of the original participants.
Most of the participants were White (51.8% Hispanic and 35.1% non-Hispanic), with an almost equal split among the sexes (50.4% men, 49.6% women). Around one-fifth reported a lifetime diagnosis of asthma when asked in the first wave survey.
Bronchitic symptoms were the most common respiratory symptom across all of the four waves of surveys – reported by 19.4% of individuals in wave 1, 22.5% in wave 2, 23.5% in wave 3, and 26.0% in wave 4. Respective values for current wheeze were 12.2%, 13.9%, 14.2%, and 14.8%.
Shortness of breath was added as a question in the second wave of surveys and was reported by 16.5% of participants, with 18.1% and 17.0% reporting it in waves 3 and 4, respectively.
Multiple statistical analyses were performed including several sensitivity analyses, one of which took account of participants’ lifetime history of asthma, and the association between e-cigarette use and respiratory symptoms persisted, the researchers report.
In another sensitivity analysis, use of tobacco or cannabis in the past 30 days was excluded, which just strengthened the associations and supports a “causal interpretation,” says the team.
This type of analysis is not without limitations, the researchers acknowledge, such as the collection of data via self-report questionnaires, and that some items such as shortness of breath and cannabis use were not added until the second and third waves, respectively.
Nevertheless, they conclude that the results show there is an association between e-cigarette use and respiratory symptoms and that their findings “strengthen epidemiological evidence of adverse respiratory effects of e-cigarettes that is consistent with known effects of e-cigarette ingredients.”
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