Non-dieting group interventions for overweight and obese women: what predicts non-completion and does completion improve outcomes?

OBJECTIVE: To determine factors which predict non-completion of group non-dieting interventions for overweight women, and to investigate whether completion improves outcomes. DESIGN: First, baseline predictors of non-completion were identified; then changes at 10 weeks and 12 months were compared between completers and non-completers of 10-week non-dieting interventions. SETTING: General community. SUBJECTS: Participants were 119 women (aged 25-65 years, BMI > or = 28 kg/m2) with at least one cardiovascular risk factor. Participants who attended at least eight of the ten sessions were classified as completers, and non-completers were those who attended fewer than eight sessions. Measures included BMI, blood pressure, psychological distress, lifestyle behaviours and eating self-efficacy. RESULTS: Logistic regression analyses indicated that women were less likely to be non-completers at non-dieting group programmes if, at baseline, they were more highly educated or had healthier nutrition behaviours (controlling for education). Only healthier nutrition behaviour was negatively associated with non-completion in the final model. Twelve months after the intervention, completers showed significantly greater improvements in body weight (mean change -0.53 kg), systolic and diastolic blood pressure (-6.3 and -4.1 mmHg, respectively), stress management behaviour score (+0.5) and psychotic symptoms score (-0.1) than non-completers (all P < 0.05). CONCLUSIONS: Highly educated women already engaging in some healthier lifestyle choices were less likely to be non-completers in non-dieting group programmes. Since important treatment outcomes vary according to attendance, future trials of non-dieting interventions should report the effects of completion on outcomes.