Table 1.
List of studies included in the review and assessment of study methodologies
| Article | Study design | Outcome of interest? | Assessed Reason for Use: Cessation? | Appropriate study design? | Measurement: Exposure precedes outcome? (Timing) | Measurement: Assessed Dose of ENDS Use? (Dose) | Measurement: Assessed ENDS Product Type? |
|---|---|---|---|---|---|---|---|
| Bullen (2013) (57) | Randomized controlled trial | Yes | Yes | Yes | Yes | Yes | Yes |
| O’Brien (2015) (60) | Randomized controlled trial | Yes | Yes | Yes | Yes | Yes | Yes |
| Caponnetto (2013) (58) | Randomized controlled trial | Yes | Yes | Yes | Yes | Yes | Yes |
| Tseng (2016) (61) | Randomized controlled trial | Yes | Yes | Yes | Yes | Yes | Yes |
| Vickerman (2017) (101) | Longitudinal study with comparison group | Yes | Yes | Yes | Yes | No | Yes |
| Zawertailo (2017) (115) | Longitudinal study with comparison group | Yes | Yes | Yes | No | No | No |
| Shi (2016) (116) | Longitudinal study with comparison group | Yes | Yes | Yes | No | No | No |
| Adriens (2014) (59) | Randomized controlled trial | Yes | Yes | No | No | Yes | Yes |
| Pearson (2015) (81) | Longitudinal study with comparison group | Yes | Yes | No | No | No | No |
| Vickerman (2013) (80) | Longitudinal study with comparison group | Yes | Yes | No | No | No | No |
| Etter (2014) (63) | Longitudinal study with no comparison group | Yes | Yes | No | Yes | Yes | Yes |
| Polosa (2015) (70) | Longitudinal study with no comparison group | Yes | Yes | No | Yes | No | Yes |
| Stein (2016) (105) | Longitudinal study with no comparison group | Yes | Yes | No | Yes | Yes | Yes |
| James (2016) (106) | Longitudinal study with no comparison group | Yes | Yes | No | Yes | Yes | Yes |
| Nolan (2016) (102) | Longitudinal study with no comparison group | Yes | Yes | No | Yes | Yes | Yes |
| Goniewicz (2013) (84) | Cross-sectional survey | Yes | Yes | No | No | Yes | Yes |
| Dawkins (2013) (85) | Cross-sectional survey | Yes | Yes | No | No | Yes | Yes |
| Tackett (2015) (86) | Cross-sectional survey | Yes | Yes | No | No | Yes | Yes |
| Rutten (2015) (87) | Cross-sectional survey | Yes | Yes | No | No | Yes | No |
| Brown (2014) (91) | Cross-sectional survey | Yes | Yes | No | No | No | No |
| Zhu (2013) (90) | Cross-sectional survey | Yes | Yes | No | No | No | No |
| Allem (2015) (107) | Cross-sectional survey | Yes | Yes | No | No | No | No |
| McQueen (2016) (112) | Cross-sectional survey | Yes | Yes | No | No | No | No |
| Pechacek (2016) (113) | Cross-sectional survey | Yes | Yes | No | No | No | Yes |
| Beard (2016) (117) | Cross-sectional survey | Yes | Yes | No | No | No | No |
| Filippidis (2016) (118) | Cross-sectional survey | Yes | Yes | No | No | No | No |
| Caponnetto (2011) (100) | Case series | Yes | Yes | No | No | No | Yes |
| Hatsukami (2017) (123) | Randomized controlled trial | Yes | No | Yes | No | No | No |
| Biener (2014) (72) | Longitudinal study with comparison group | Yes | No | Yes | Yes | Yes | No |
| Brose (2015) (73) | Longitudinal study with comparison group | Yes | No | Yes | Yes | Yes | No |
| Al-Delaimy (2015) (78) | Longitudinal study with comparison group | Yes | No | Yes | Yes | No | No |
| Borderud (2014) (75) | Longitudinal study with comparison group | Yes | No | Yes | Yes | No | No |
| Choi (2014) (77) | Longitudinal study with comparison group | Yes | No | Yes | Yes | No | No |
| Grana (2014) (74) | Longitudinal study with comparison group | Yes | No | Yes | Yes | No | No |
| Prochaska (2014) (76) | Longitudinal study with comparison group | Yes | No | Yes | Yes | No | No |
| Hitchman (2015) (79) | Longitudinal study with comparison group | Yes | No | Yes | No | Yes | Yes |
| Adkison (2013) (82) | Longitudinal study with comparison group | Yes | No | Yes | No | No | No |
| Polosa (2016) (119) | Longitudinal study with comparison group | Yes | No | Yes | Yes | Yes | No |
| Manzoli (2016) (120) | Longitudinal study with comparison group | Yes | No | Yes | Yes | Yes | No |
| Polosa (2016b) (121) | Longitudinal study with comparison group | Yes | No | Yes | Yes | Yes | No |
| Zhuang (2016) (122) | Longitudinal study with comparison group | Yes | No | Yes | Yes | No | No |
| Caponnetto (2013) (64) | Longitudinal study with no comparison group | Yes | No | No | Yes | Yes | Yes |
| Nides (2014) (68) | Longitudinal study with no comparison group | Yes | No | No | Yes | Yes | Yes |
| Polosa (2014) (67) | Longitudinal study with no comparison group | Yes | No | No | Yes | Yes | Yes |
| Polosa (2011) (65) | Longitudinal study with no comparison group | Yes | No | No | Yes | Yes | Yes |
| Polosa (2014) (66) | Longitudinal study with no comparison group | Yes | No | No | Yes | Yes | Yes |
| Berg (2014) (62) | Longitudinal study with no comparison group | Yes | No | No | Yes | Yes | No |
| Polosa (2016) (103) | Longitudinal study with no comparison group | Yes | No | No | Yes | No | Yes |
| Pratt (2016) (104) | Longitudinal study with no comparison group | Yes | No | No | Yes | Yes | Yes |
| Farsalinos (2013b) (89) | Cross-sectional survey | Yes | No | No | No | Yes | Yes |
| Siegel (2011) (88) | Cross-sectional survey | Yes | No | No | No | Yes | Yes |
| Christensen (2014) (94) | Cross-sectional survey | Yes | No | No | No | No | No |
| Lee (2014) (93) | Cross-sectional survey | Yes | No | No | No | No | No |
| Popova (2013) (92) | Cross-sectional survey | Yes | No | No | No | No | No |
| Wagener (2014) (98) | Clinical laboratory study | Yes | No | No | Yes | No | Yes |
| Manzoli (2015) (83) | Longitudinal study with comparison group | Yes | No | Yes | Yes | Yes | No |
| Grace (2015) (69) | Longitudinal study with no comparison group | Yes | No | No | Yes | No | Yes |
| Pacifici (2015) (71) | Longitudinal study with no comparison group | Yes | No | No | Yes | No | Yes |
| Fraser (2015) (96) | Cross-sectional survey | Yes | No | No | No | Yes | Yes |
| Gallus (2014) (95) | Cross-sectional survey | Yes | No | No | No | Yes | Yes |
| Dutra (2014) (114) | Cross-sectional survey | Yes | No | No | No | No | No |
| Lechner (2015) (97) | Cross-sectional survey | Yes | No | No | No | Yes | No |
| Hiscock (2015) (111) | Cross-sectional survey | Yes | No | No | No | No | No |
| Etter (2016) (110) | Cross-sectional survey | Yes | No | No | No | No | No |
| Andler (2016) (108) | Cross-sectional survey | Yes | No | No | No | Yes | No |
| Busch (2016) (109) | Cross-sectional survey | Yes | No | No | No | No | No |
| McRobbie (2015) (99) | Clinical laboratory study | Yes | No | No | Yes | Yes | Yes |
| Campagna (2016) (54) | Randomized controlled trial | No | Yes | Yes | Yes | Yes | Yes |
| Cibella (2016) (55) | Randomized controlled trial | No | Yes | Yes | Yes | Yes | Yes |
| Pulvers (2014) (39) | Cross-sectional survey | No | Yes | No | No | Yes | No |
| Pepper (2014) (34) | Cross-sectional survey | No | Yes | No | No | No | No |
| Pokhrel (2013) (41) | Cross-sectional survey | No | Yes | No | No | No | No |
| Ramo (2015) (40) | Cross-sectional survey | No | No | No | No | No | No |
| Farsalinos (2013) (33) | Cross-sectional survey | No | No | No | No | Yes | No |
| Pokhrel (2014) (35) | Cross-sectional survey | No | No | No | No | No | No |
| Pokhrel (2014) (36) | Cross-sectional survey | No | No | No | No | No | No |
| Stein (2015) (52) | Cross-sectional survey | No | Yes | No | No | No | No |
| Beard (2015) (37) | Cross-sectional survey | No | Yes | No | No | No | No |
| Harrell (2015) (46) | Cross-sectional survey | No | No | No | No | Yes | Yes |
| Kinnunen (2015) (51) | Cross-sectional survey | No | No | No | No | No | No |
| Heydari (2015) (38) | Cross-sectional survey | No | No | No | No | No | No |
| Cho (2016) (49) | Cross-sectional survey | No | No | No | No | No | No |
| Lippert (2016) (48) | Cross-sectional survey | No | No | No | No | No | No |
| Camenga (2016) (42) | Cross-sectional survey | No | Yes | No | No | Yes | No |
| Huerta (2017) (50) | Cross-sectional survey | No | No | No | No | No | No |
| LeVault (2016) (44) | Cross-sectional survey | No | Yes | No | No | No | No |
| Spears (2016) (45) | Cross-sectional survey | No | Yes | No | No | No | No |
| Thrul (2017) (43) | Cross-sectional survey | No | Yes | No | No | No | No |
| Jorenby (2017) (56) | Clinical laboratory study | No | No | Yes | Yes | Yes | Yes |
| Copp (2015) (47) | Clinical laboratory study | No | No | No | No | No | Yes |
| Silver (2016) (53) | Case series | No | No | No | No | Yes | No |