Table 3

Mean number of conventional cigarettes used per day at baseline and the end of study*

Author, yearGroupsMean no. of conventional cigarettes used per day at baselineMean no. of conventional cigarettes used per day at the end of studyBiochemically quitters (no. of events per no. of total participants)Self-reported quitters (no. of events per no. of total participants)
Adriaens, 201433ENDS 120.17.0†3/134/13
ENDS 220.68.1†3/123/12
Control/ENDS‡,§16.77.7†4/134/13
Bullen, 201334–39ENDS18.40.7¶21/241Not available
ENNDS17.70.73/57Not available
NRT17.60.8¶17/215Not available
Caponnetto, 2013257.2 mg ENDS19.0 (14.0–25.0)**12 (5.8–20)**,††Combined ENDS groups: 22/128Not available
7.2 mg ENDS plus 5.4 mg ENDS21.0 (15.0–26.0)**14 (6–20)**,††Not available
ENNDS22.0 (15.0–27.0)**12 (9–20)**,††4/55Not available
Al-Delaimy, 201540ENDS14.1‡‡13.8§§Not available12/179
ENNDSNot available32/145
Biener, 201529ENDS intermittent use16.7¶¶Not availableNot availableCombined ENDS groups: 42/331
ENDS intensive use17.1¶¶Not availableNot available
No ENDS15.4¶¶Not availableNot available82/364
Brose, 201526–28ENDS daily users14.313.0***Not available7/86
ENDS non-daily users13.513.9***Not available25/263
No ENDS†††13.313.5Not available168/1307
Hajek, 201546ENDSNot availableNot availableNot applicable‡‡‡Not applicable‡‡‡
No ENDSNot availableNot availableNot applicable‡‡‡Not applicable‡‡‡
Harrington, 201545ENDS14.1§§§10.3§§§Not available21/171
No ENDS11.9§§§9.8§§§Not available62/464
Manzoli, 201542ENDS onlyNot available12Not availableNot available
Tobacco cigarettes only14.112.8101/491Not available
Dual smoking14.99.351/232Not available
Borderud, 201441ENDS13.712.3Not available25/58
No ENDS12.410.1Not available158/356
Prochaska, 201443ENDS17.010.021/101Not available
No ENDS17.010.1162/855Not available
Vickerman, 201344ENDS used for 1 month or more19.413.5Not available59/273
ENDS used for less than 1 month18.914.0Not available73/439
No ENDS (never tried)18.112.9Not available535/1711
  • *When authors provided data for different time points, we presented the data for the longest follow-up.

  • †8 months from start of intervention.

  • ‡Control group consisted of received the e-cig and e-liquid (six bottles) for 2 months at the end of session 3 (eight of the 16 participants of the control group received the ‘Joyetech eGo-C’ and the remaining eight participants received the ‘Kanger T2-CC’).

  • §For the first 2 months control group consisted of no e-cigarettes use. After that period, the participants of control group received the e-cig and e-liquid. ENDS1=’Joyetech eGo-C’ e-cig and ENDS2=’Kanger T2-CC’ e-cig.

  • ¶For those reporting smoking at least one cigarette in past 7 days.

  • **Data shown as median and interquartile.

  • ††At 6 months after the last laboratory session.

  • ‡‡Of the 1000 subjects, 993 responded to the question “How many conventional cigarettes smoked per day during the past 30 days”.

  • §§Of the 1000 subjects, 881 responded to the question “How many cigarettes smoked per day during the past 30 days.”

  • ¶¶Number of conventional cigarettes used in the prior month at baseline.

  • ***No. of cigarette per week divided by 7 days.

  • †††The comparator comprises of current non-users of e-cig which included never-users and those who had previously tried but were not using at the moment.

  • ‡‡‡Not applicable because they followed participants only for 4 weeks, but the study reported adverse events at 1 week or longer.

  • §§§Data for baseline current e-cig users.

  • e-cig, eletronic cigarettes; ENDS, electronic nicotine delivery system; ENDS1 and ENDS 2, the e-cig groups received the e-cig and four bottles of e-liquid at session 1 (group e-cig1 received the ‘Joyetech eGo-C’ and group e-cig2 received the ‘Kanger T2-CC’); at session 2; ENNDS, electronic non-nicotine delivery systems; No., number; RYO, roll your own (loose tobacco) cigarettes.