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Aims: To examine heterogeneity in outcome following treatment for smoking cessation with combined bupropion SR and behavioral counseling in women and men., Design, Setting, Participants: This study included 875 women and 649 men recruited from a large health-care system and randomized to one of four combinations of treatment [two dosage levels of bupropion SR (Zyban, 150 mg and 300 mg) were crossed with two counseling programs of lower and higher intensity to create a four-cell design]., Measurements and Findings: A comprehensive set of relevant individual characteristics prior to treatment and treatment characteristics was included in the analysis. Smoking outcome at 12 months was defined as point-prevalence of any regular smoking within the 7 days prior to follow-up contact. Classification and regression tree analysis identified six subgroups in women that ranged in proportion of non-smokers from 9.8% to 42.9% and six subgroups in men that ranged in proportion of non-smokers from 17.3% to 50.0%., Conclusions: These results indicate the presence of a substantial amount of variation in treatment outcome among women and men receiving combined bupropion SR and counseling. Variation in outcome could be reduced by providing treatments tailored to subgroups of individuals who are at exceptionally high risk for smoking following cessation.

To identify subgroups of smokers with different success rates, we applied "tree-structured survival analysis" (TSSA) to data from a previously published trial of transdermal nicotine. The subjects who received active treatment (14 mg patch, n = 275, or the 21 mg patch, n = 262) constituted the sample for this analysis. Using age, gender, the Fagerstrom Tolerance Questionnaire (FTQ), motivation to quit, number of cigarettes smoked at baseline, and body mass index (BMI) as classification variables, TSSA identified two subgroups within the 14 mg patch group and four subgroups of smokers within the 21 mg patch group. Among those receiving the 14 mg patch, individuals with a BMI greater than 26.4 kg/m2 relapsed sooner than did those with a BMI less than or equal to this value. Within the 21 mg patch group, the survival curve for males was significantly different from that observed in females, with males experiencing a longer time to relapse after treatment than did females. Among females, those with a higher motivation to quit relapsed more slowly than did those women with less motivation to quit. This information may be helpful to clinicians seeking to match specific patients to specific treatments with traditional nicotine in order to maximize treatment outcomes.