ABSTRACT
INTRODUCTION: Electronic cigarette (e-cigarette) use is gaining popularity among adults. Monitoring e-cigarette-induced respiratory symptoms is crucial for both clinical and regulatory purposes. We systematically reviewed the current literature to understand the prevalence of respiratory symptoms among exclusive e-cigarette users, dual users, and former smokers. METHODS: Databases searched included PubMed, CINAHL, Cochrane Library, Embase, and Scopus. We included all English-language, empirical quantitative articles that explored the prevalence of e-cigarette-related respiratory symptoms. Random-effects models were utilized in conducting the meta-analyses. The quality of identified studies was evaluated using the NIH Study Quality Assessment Tools. This study is registered with PROSPERO(#CRD42020165973). RESULTS: The literature search identified 1240 references. After removing duplicates and screening for eligibility, 168 studies were included in the final review. The majority of included studies reported a wide range of adverse respiratory symptoms. The respiratory symptoms were prevalent among the exclusive e-cigarette users, dual users, and those who switched from combustible cigarettes to e-cigarettes. Further, out of the RCT studies, 5 were rated as good quality, while 3 were rated as fair. Among the observational studies, 24 were rated as good quality, and 9 were rated as fair. The two experimental studies were both rated as fair quality. CONCLUSIONS: Continued monitoring of respiratory symptoms among e-cigarette users is warranted. Due to the heterogeneity and inconsistencies among studies, which limit result interpretation and highlight the need for studies assessing causal inference, further research using robust study designs is essential. This will provide clinicians with comprehensive knowledge about the potential respiratory risks of e-cigarette use.
ABSTRACT
INTRODUCTION: There is a paucity of studies on e-cigarette use among adults with chronic lung disease. In the present study, we aimed to assess whether psychosocial or cognitive factors elucidate the relationship between chronic lung disease (CLD) and susceptibility to e-cigarette use and whether the relationship between CLD and e-cigarette use is conditional on the presence of respiratory symptoms. METHODS: We recruited adults aged ≥18 years in Alabama with CLD from university medical clinics (n=140) and individuals without CLD (n=123 as a reference group). Information on sociodemographics, susceptibility to e-cigarette use, psychosocial factors, and cognitive factors were collected. Mediation analysis was used to assess whether the psychosocial factors or cognitive factors explained the association between CLD and susceptibility to using e-cigarettes, and moderation analysis was conducted to determine if respiratory factors would change the association between CLD and susceptibility to e-cigarette use. RESULTS: Psychosocial factors (stress, depression, anxiety) and e-cigarette positive expectancy were notably high among individuals with CLD. Having CLD was associated with a lower likelihood of susceptibility to e-cigarette use. Higher levels of stress, being a smoker, boredom, taste/sensorimotor manipulation, and social facilitation were associated with higher odds of susceptibility to using e-cigarettes among individuals with CLD. Mediation analysis indicated a statistically significant indirect effect of CLD on the susceptibility to using e-cigarettes through stress and boredom reduction. We did not find a statistically significant interaction between CLD and respiratory symptoms affecting susceptibility to using e-cigarettes. CONCLUSIONS: Individuals with CLD often exhibit stress, depression, and a positive view of e-cigarettes but are generally less inclined to use them. Stress, smoking habits, boredom, taste, and social influence can increase their susceptibility to e-cigarette use. Our findings call for further exploration to evaluate the temporal relationship between CLD status, psychosocial factors, cognitive factors, and susceptibility to using e-cigarettes. TRIAL REGISTRATION: The study was registered on ClinicalTrials.gov, on 5 November 2019. Identifier: NCT04151784.
