B26-11 How Vaping Shapes Pulmonary Function and Feno: A Meta-analysis of Users Versus Non-users

Rationale WHO estimates 1.3 billion smokers globally, with 8.9 million smoking-related diseases and deaths anually. E-cigarettes were initially marketed as an alternative and smoking cessation tool. This led to the decline of combustible cigarettes and the rise of vaping, from 1% (2017) to 9% in 2023 per country. However, it attracted never-smokers, especially those aged 15-24 years. Despite reports of E-cigarette or vaping product use-associated lung injuries(EVALI) and other pulmonary problems, little is known about the long-term effects of ENDS. Aim: To assess the lung function and fractional exhaled nitric oxide (FeNO) of ENDS users versus non-ENDS and non-tobacco users. Methods Authors followed the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) 2009 checklist. A systematic search was performed with academic databases EMBASE, Medline, Scopus, Ovid, Web of Science, Cochrane Library, Pubmed, and John Hopkins Library. Search range started from 2004, when e-cigarette was developed, until March 18, 2025. FEV1, FVC, FEV1/FVC and FeNO levels of ENDS users versus Non-ENDS users were measured. Stata v18/SE meta-analysis library was used in all analyses. Risk of Bias assessments were performed using the ROB 2 and ROB-I tools. Results Search returned 19,881 studies, of which 271 studies were included for quality assessment. Ten studies were eventually included. A decline in lung function was seen among ENDS users as evidenced by a statistically significant lower FEV1/FVC (%) by 2.46% (95% CI: 0.72% - 4.20%, p-value = 0.01)(Fig.1). FeNO levels (in ppb) showed statistically significant lower results among ENDS users by 2.78 (95% CI: 0.14 - 5.41, p-value = 0.04). No differences were noted in FEV1 (in L/s or % predicted) and FVC. Conclusion The search returned 19,881 studies, of which 271 studies were included for further inclusion and quality assessment. Ten studies were eventually included. A decline in lung function was seen among ENDS users as evidenced by a statistically significant lower FEV1/FVC (%) by 2.46% (95% CI: 0.72% - 4.20%, p-value = 0.01). FeNO levels (in ppb) showed statistically significant lower results among ENDS users by 2.78 (95% CI: 0.14 - 5.41, p-value = 0.04). No differences were noted in FEV1 (in L/s or % predicted) and FVC. Decreased FEV1/FVC and FeNO suggests the potential harm of ENDS on lung function, obstructive airway disease and oxidative stress, even if they are never smokers.