Figure 2, panel B, shows the levels of continuous abstinence for the 90 days prior to each follow-up. Abstinence rates in the NS condition reached 40% at 12, 15, 18, 24, and 27 months. The GEE analysis yielded no significant main effect for Treatment condition, a main effect for Time [χ2 (8) = 18.85; p < .02], and no Treatment X Time interaction. An a-posteriori contrast comparing the NS condition versus CaseM plus NS+CM, however, was significant [χ2 (1) = 4.66; p < .03], indicating an overall advantage for the NS condition. This contrast had a moderate effect size of h=.30.
