Heterogeneity in 12-month outcome among female and male smokers.

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.