Results of the interaction ( GroupTime ) effects using GEE indicated that there were statistically significant differences between the three study groups over the 6-month follow-up on the ASSIST tobacco score ( Wald ( 2 ) = 8.43 , P = 0.004 ) , and past week tobacco use abstinence ( Wald ( 2 ) = 7.34 , P = 0.007 ) .