Since their introduction in the United States marketplace in 2007, e-cigarettes have been promoted as a safer alternative to conventional cigarettes, and their use has grown rapidly.

Data from the CDC reveal that in 2021, more than 5% of adults, 2.8% of middle school students, and 11.3% of high school students reported using e-cigarettes in the past 30 days. Studies have shown that ecigarettes contain more than84 hazardous chemical compounds, and they have been associated with wheezing, chronic cough, phlegm, and bronchitis in children and adults.

For a study in PLOS One, Noël C. Barengo, MD,PhD, MPH, and colleagues analyzed data from 18,079 US adults to assess the magnitude of e-cigarettes’ respiratory effects. The results reveal that e-cigarettes may increase the risk for “detrimental” respiratory symptoms, and thus cannot be considered a safe alternative to aid in smoking cessation of traditional combustible cigarettes.

“Very few studies have looked at the effects of e-cigarettes in the general US population, and most have assessed their impact on only [COPD] and asthma,” says Dr. Barengo. “Thus, the current research may underestimate the magnitude of the respiratory effects caused by e-cigarettes.”

Participants Divided into Four Categories

The data that formed the basis of the analysis were collected from adults aged 18-44 who participated in the Behavioral Risk Factor Surveillance System (BRFSS). Performed annually, BRFSS is a cross-sectional survey that leverages phone interviews with individuals to identify emerging health problems to modify public health programs and policies.

Based on survey respondents’ answers to questions about e-cigarette use in 2017, the study authors classified BRFSS participants as current every day users, current some days users, former smokers, or never smokers. They then compared the frequency of any respiratory symptoms—cough, phlegm, or shortness of breath—among the different categories of users, taking into account variables such as participant age, sex, race, lifestyle habits, and risk factors for respiratory disease.

“Our large sample size and use of systematically collected and comprehensive information from participants in multiple states are strengths that expand the generalizability of the results to the adult population in the US,” says Dr. Barengo. “However, the data are limited, in that they were self-reported, and we did not have detailed information about characteristics, such as the age at first use or daily frequency of e-cigarette use.”

E-Cigarette Users More Likely to Report Respiratory Symptoms

A key result from the research is that e-cigarette use increased the likelihood of reporting respiratory symptoms by 49% among those who used the products some days and by 29% among former users compared with those who never used e-cigarettes. Overall, never users of e-cigarettes were more often older, women, Black or Hispanic, married, and had a higher level of education and greater income than the participants who used ecigarettes. Frequency of respiratory symptoms was highest among those who were some days current users and lowest for never users of e-cigarettes (44.6% and 23.3%, respectively; P<0.0001 for differences in at least one category; Table).

“Our data showed that 2.5% and 4.2% of the sample were every day or some days e-cigarette users, respectively,” notes Dr. Barengo. “Overall, 28% of participants reported respiratory symptoms, a much higher frequency than has been previously reported.”

Future studies are needed, he says, to evaluate associations between e-cigarettes and respiratory symptoms in large population cohorts with follow-up over a longer period, as well as research on a potential dose-effect relationship between e-cigarette use and respiratory symptoms.

A key takeaway, according to Dr. Barengo, is that it is “very important that physicians assess patients’ e-cigarette use, explain to patients the hazardous effects related to the practice, counsel them to quit, and help them to do so. Public health policies should restrict sale of e-cigarettes, especially in the adolescent population, as they seem to be one of the main targets of the e-cigarette industry.”