Association between e-cigarette use and asthma: a systematic review and meta-analysis

The impact of exposure to tobacco smoke and e-cigarettes on asthma-related outcomes: Systematic review informing the EAACI guidelines on environmental science for allergic diseases and asthma

To inform the clinical practice guidelines' recommendations developed by the European Academy of Allergy and Clinical Immunology systematic reviews (SR) assessed using GRADE on the impact of environmental tobacco smoke (ETS) and active smoking on the risk of new-onset asthma/recurrent wheezing (RW)/low lung function (LF), and on asthma-related outcomes. Only longitudinal studies were included, almost all on combustion cigarettes, only one assessing e-cigarettes and LF. According to the first SR (67 studies), prenatal ETS increases the risk of RW (moderate certainty evidence) and may increase the risk of new-onset asthma and of low LF (low certainty evidence). Postnatal ETS increases the risk of new-onset asthma and of RW (moderate certainty evidence) and may impact LF (low certainty evidence). Combined in utero and postnatal ETS may increase the risk of new-onset asthma (low certainty evidence) and increases the risk of RW (moderate certainty evidence). According to the second SR (24 studies), ETS increases the risk of severe asthma exacerbations and impairs asthma control and LF (moderate certainty evidence). According to the third SR (25 studies), active smoking increases the risk of severe asthma exacerbations and of suboptimal asthma control (moderate certainty evidence) and may impact asthma-related quality-of-life and LF (low certainty evidence).

Population-Based Disease Odds for E-Cigarettes and Dual Use versus Cigarettes

BACKGROUND: E-cigarettes are promoted as less harmful than cigarettes. There has not been a direct comparison of health effects of e-cigarettes or dual use (concurrently using e-cigarettes and cigarettes) with those of cigarettes in the general population. METHODS: Studies in PubMed, EMBASE, Web of Science, and PsychINFO published through October 1, 2023, were pooled in a random-effects meta-analysis if five or more studies were identified with a disease outcome. We assessed risk of bias with Risk Of Bias In Non-randomized Studies of Exposure and certainty with Grading of Recommendations, Assessment, Development, and Evaluations. Outcomes with fewer studies were summarized but not pooled. RESULTS: We identified 124 odds ratios (94 cross-sectional and 30 longitudinal) from 107 studies. Pooled odds ratios for current e-cigarette versus cigarette use were not different for cardiovascular disease (odds ratio, 0.81; 95% confidence interval, 0.58 to 1.14), stroke (0.73; 0.47 to 1.13), or metabolic dysfunction (0.99; 0.91 to 1.09) but were lower for asthma (0.84; 0.74 to 0.95), chronic obstructive pulmonary disease (0.53; 0.38 to 0.74), and oral disease (0.87; 0.76 to 1.00). Pooled odds ratios for dual use versus cigarettes were increased for all outcomes (range, 1.20 to 1.41). Pooled odds ratios for e-cigarettes and dual use compared with nonuse of either product were increased (e-cigarette range, 1.24 to 1.47; dual use, 1.49 to 3.29). All included studies were assessed as having a low risk of bias. Results were generally not sensitive to study characteristics. Limited studies of other outcomes suggest that e-cigarette use is associated with additional diseases. CONCLUSIONS: There is a need to reassess the assumption that e-cigarette use provides substantial harm reduction across all cigarette-caused diseases, particularly accounting for dual use.

Respiratory health effects of e-cigarette substitution for tobacco cigarettes: a systematic review

BACKGROUND

E-cigarettes (electronic nicotine delivery system, ENDS) have been presented as a harm reduction strategy for people who smoke tobacco cigarettes but who cannot achieve abstinence, or for those who wish to continue to enjoy nicotine and the habit of smoking. What are the health effects of the substitution of ENDS for tobacco cigarettes? This systematic review evaluates the evidence of human clinical tests on the respiratory effects of ENDS use in participants who smoke tobacco cigarettes.

METHODS

A registered and published protocol was developed conforming to PRISMA 2020 and AMSTAR2 standards. The literature search was conducted in PubMed, Scopus, and the CENTRAL Cochrane Library and updated to May 2022. Three supplementary searches and a grey literature search were performed. Studies were evaluated with the JBI quality tools and the Oxford Catalogue of Bias. Due to the heterogeneity (diversity) of the studies, a narrative data synthesis was performed on the test findings plus three sub-group analyses.

RESULTS

The review consists of sixteen studies and twenty publications. Spirometry tests comprised the majority of the data. In total, 66 respiratory test measurements were reported, out of which 43 (65%) were not significant. Statistically significant findings were mixed, with 9 tests showing improvements and 14 measuring declines, none of which was clinically relevant. Ten studies were rated at a high risk of bias, and six had some concerns primarily due to inadequate research designs and the conduct of the studies. Reporting bias was documented in thirteen studies.

CONCLUSIONS

Most of the studies showed no difference in respiratory parameters. This indicates that ENDS substitution for smoking likely does not result in additional harm to respiratory health. Due to the low quality of the studies, confidence in the conclusions is rated as low. Robust studies with a longer duration and sufficient power are required to validate any potential benefits or possible harms of ENDS substitution. Registration PROSPERO #CRD42021239094, International Registered Report Identifier (IRRID): DERR1-10.2196/29084.

E-cigarettes and asthma in adolescents

PURPOSE OF REVIEW

E-cigarettes have been long purported to be a mechanism of harm reduction in current smokers. However, market expansion to adolescents has been aggressive, despite government interventions. Research examining the adverse effects of e-cigarettes in teens with asthma has been limited. We discuss the most recent data on the pulmonary manifestations of e-cigarettes use and exposure in adolescents with asthma.

RECENT FINDINGS

Adolescents with asthma are more likely to be e-cigarette users than those without asthma and more likely to have asthma exacerbations. Increased pulmonary inflammatory cytokines have been seen in e-cigarette users and mouse models. Yet, providers are not confident in e-cigarette screening and counselling despite acknowledging adolescents are using e-cigarettes regularly.

SUMMARY

Since the introduction of e-cigarettes into the United States market in 2007, adolescents use of these products has risen, even after a brief decline during the height of the COVID-19 pandemic. This review will describe the most recent studies on e-cigarette use trends, cytotoxicity of e-cigarette aerosol and associations with the diagnosis and symptoms of asthma. Knowledge gaps, advocacy efforts, evidence on e-cigarette cessation will be highlighted.

Health Effects of Electronic Cigarettes: An Umbrella Review and Methodological Considerations

E-cigarettes are often marketed as a safer alternative to combustible cigarettes. However, their health effects, especially those associated with long-term use, remain largely uncertain. We conducted an umbrella review of the cardiopulmonary and carcinogenic risks of e-cigarette use, distinguishing between short-term and long-term health effects. The search for systematic reviews was conducted across four electronic databases through 25 January 2022. Methodological quality was assessed using the AMSTAR-2 quality appraisal tool. Seventeen systematic reviews, including five meta-analyses, were included in our umbrella review. There was a clear underreporting of e-cigarette devices and e-liquid types, e-cigarette and cigarette exposure, and the health and smoking status of study participants. Overall, the findings suggest that short-term use of e-cigarettes may be associated with acute cardiopulmonary risks, although to a lesser extent than cigarette use. Long-term e-cigarette use may have pulmonary/respiratory benefits in those who switch from chronic cigarette smoking, particularly in individuals with asthma and chronic obstructive pulmonary disease (COPD). Evidence on intermediate and long-term carcinogenic effects is lacking. This umbrella review underscores the urgent need for systematic reviews with better adherence to established reporting guidelines, consistent definitions of duration of e-cigarette use, a focus on newer devices, and accounting for the impacts of former or current smoking.