Table 1.
Characteristics of studies examining the effects of e-cigarettes on lung function.
| Study | Location | Design | Intervention/Exposure and timing | Comparator | Sample size | Participant population | Outcomes of interest |
|---|---|---|---|---|---|---|---|
| Short-term studies | |||||||
| Palamidas 2017 | Greece | NRSI (pre-post) | 10 min vaping with EC |
Smokers: none Non-smokers: 11 mg or 0 mg nicotine |
76 |
55 smokers: 16 COPD: 12/16 male, 61 ± 9 years; 11 asthma: 4/11 male, 37 ± 10 years; 28 no respiratory history: 16/28 male, 41 ± 10 years 21 healthy nonsmokers: 9 in 11 mg group: 5/9 male,35 ± 13 years; 12 in 0 mg group: 7/12 male, 34 ± 10 years |
FEV1, FVC, FEV1/FVC, airway resistance, specific airway conductance, oxygen saturation |
| Palamidas 2013 | Greece | NRSI (pre-post) | 10 min vaping with EC |
Smokers: none Non-smokers: 11 mg or 0 mg nicotine |
70 |
Group A (nicotine e-cig): nine never-smokers and 51 smokers (24 with no overt airway disease, 11 asthma, 16 COPD) Group B (nicotine-free e-cig): 10 never-smokers |
airway resistance, specific airway conductance |
| Coppeta 2018 | Italy | NRSI (pre-post) | EC and CC, 15-min sessions on different days (15 puffs EC) | EC or CC | 30 | 30 nonsmokers: 17/30 male, 32.6 ± 2.75 years | FEF25-75, FEV1, FEV1/FVC |
| Kizhakke Puliyakote 2021 | USA (CA) | NRSI (non-vaping reference group) | EC, unspecified duration (only in baseline vapers) | non-vapers or vapers | 16 |
9 vapers: 6/9 male, 21 ± 2 years Seven nonsmokers: 4/7 male, 23 ± 5 years |
FEV1, FEV1/FVC, FVC, oxygen saturation |
| Ferrari 2015 | Italy | RCT | CC and nicotine-free EC ad libitum for 5 minutes in two different sessions | EC or CC | 20 |
Ten smokers: 4/10 male, 42.3 ± 12.6 years Ten nonsmokers: 7/10 male, 36.2 ± 12.3 years |
FEF25, FEF50, FEF75, FEV1, FEV1/FVC, FVC |
| Boulay 2017 | Canada | RCT | Three inhalations of EC per minute for 1 h; 2 × 1-h sessions 1 week apart | none | 30 | 30 subjects, all nonsmokers: 20 healthy (age 20–37 years); ten asthmatic (age 21–40 years) | FEV1, FEV1/FVC, FVC, oxygen saturation |
| Staudt 2018 | USA (NY) | RCT | Two sessions 30 min apart, ten puffs EC | nicotine or non-nicotine | 10 |
Nicotine group, seven nonsmokers: 4/7 male, 40.4 ± 11.2 years Non-nicotine group, three nonsmokers: 1/3 male, 39.7 ± 6.7 years |
FEV1, FEV1/FVC, FVC, oxygen saturation |
| Long-term studies | |||||||
| Polosa 2017 | Italy | NRSI (cohort study) | 3.5 year follow-up of nonsmokers and vapers at 12 (±1), 24 (±2), and 42 (±2) months after baseline visits | none | 21 |
9 vapers: 6/9 male, 26.6 ± 6.0 years 12 nonsmokers: 8/12 male, 27.8 ± 5.2 years |
FEF25, FEF25-75, FEV1, FEV1/FVC, FVC |
CC conventional cigarette, COPD chronic obstructive pulmonary disease, EC electronic cigarette, FEF25 forced expiratory flow 25%, FEF50 forced expiratory flow 50%, FEF75 forced expiratory flow 75%, FEF25-75 maximum mid-expiratory flow, FEV1 forced expiratory volume in one second, NRSI non-randomized study of intervention, RCT randomized controlled trial.