Table 1

Overall study characteristics

Control groups reported* (n 33)ControlMI groups reported* (n 34)MI
Mean (SD) or % (n)Mean (SD) or % (n)
Total number of participants46944791
% Females in study sample2968 (27)3068 (27)
% White people in study sample1861 (37)1957 (38)
Baseline age2934 (13)3035 (13)
Baseline cigarettes per day2815 (6)2816 (6)
Baseline sample size33142 (147)34141 (139)
Study included pharmacotherapy3345% (n 15)3447% (n 16)
Biochemical verification of abstinence3382% (n 27)3482% (n 28)
MI combined with other interventions3474% (n 25)
Fidelity check conducted3450% (n 17)
Duration of staff training in MI (in hours)1152 (72)
Duration of MI intervention (in minutes)32101 (122)
VariablePapers reportingMean (SD)/% (n)
Publication year302004 (2.6)
Study conducted in the USA3171% (n 22)
Cluster RCT3116% (n 5)
  • * Smith and colleagues30 reported on MI and control intervention effects for both low and high risk smokers. Both Hyman and colleagues31 and Ahluwalia and colleagues29 reported intervention effects for two different MI conditions, and Ahluwalia and colleagues29 also had two control conditions.

  • 31 papers included, but one study consisted of unpublished data (Hannover and colleagues).

  • MI, motivational interviewing intervention; n, number of arms/papers; RCT, randomised controlled trial.