Table 3

MI effects by follow-up time point and population

Control % abstinent (total n)MI % abstinent (total n)DifferenceAdjusted OROR 95% CIAdjusted p value
Time point*
4–8 weeks8.9% (1141)11.0% (1141)2.1%1.47(0.97 to 2.23)0.067
10–12 weeks7.0% (812)11.6% (846)4.6%1.66(1.08 to 2.56)0.022
22–26 weeks11.6% (4215)14.0% (4279)2.4%1.44(1.11 to 1.88)0.006
52 weeks12.7% (1943)14.1% (1983)1.4%1.25(0.91 to 1.71)0.177
Population
Adolescents6.0% (235)11.5% (295)5.5%2.29(1.34 to 3.89)0.002
Adults with chronic illnesses8.4% (667)13.4% (746)5.0%1.34(0.89 to 2.01)0.157
Adults11.9% (2319)14.7% (2289)2.8%1.44(1.04 to 2.01)0.029
Pregnant/postpartum women14.1% (994)13.8% (949)−0.3%1.00(0.61 to 1.62)0.990
  • * The adjusted OR and adjusted p value describe the effect for each time period from a multiple logistic regression model with a random intercept and a random slope for the treatment effect.

  • The adjusted OR and adjusted p value describe the overall effect for each subgroup using data from all time points entered into a multiple logistic regression with a random intercept for study and a random slope for the treatment effect. Dummy variables for time were included in the model. For ease of presentation, we only present percentage abstinent data from the 22–24-week follow-up time point.

  • MI, motivational interviewing intervention; n, sample size.