Table 1

Characteristics of included studies (n=51)

Sample characteristicsN (%)US studies (n=37),
N (%)
International studies (n=14),
N (%)
PopulationYouth only13 (25)9 (24)4 (29)
Adults only30 (59)22 (59)8 (57)
Both youth and adults8 (16)6 (16)2 (14)
DesignCross-sectional47 (92)33 (89)14 (100)
Longitudinal4 (8)4 (11)0 (0)
Sampling (not mutually exclusive)Convenience35 (69)23 (62)12 (86)
Probability19 (37)17 (46)2 (14)
Outcome measure (not mutually exclusive)Taste, appeal, perceived risk14 (27)10 (27)4 (29)
Reasons for use13 (25)11 (30)2 (14)
Susceptibility, intention to try/initiation17 (33)11 (30)6 (43)
Preference9 (18)7 (19)2 (14)
Current use behaviours12 (24)10 (27)2 (14)
Quit intention/quitting behaviour10 (20)7 (19)3 (21)