Table 1

Product types and outcome measures of included studies

Sample characteristicsNUS* studies (n=23)Non-US† studies (n=17)
Product type
 E-cigarette17107
 Cigarette1046
 Little cigar, cigarillo, cigar422
 Hookah321
 Various tobacco products321
 Smokeless tobacco220
 Bidi110
Outcome measures‡
 Taste, appeal, risk perceptions1147
 Preference1046
 Expectancies and beliefs633
 Reasons for use752
 Intention to try, initiation1275
 Progression to regular use211
 Dual/poly use321
 Quit intention and quitting behaviour422
  • *One study included participants (13%) outside the USA.20

  • †One study included participants (41%) from the USA.21

  • ‡Categories are not mutually exclusive.