Dropout in cognitive behavioural treatment (CBT) in adults with overweight: a systematic review

Introduction: Although dietary treatment can significantly improve health in adults with overweight, high attrition is a common problem in interventions with serious consequences for weight loss management and frustration. The strategy of combining dietary prescriptions and recommendations for physical activity with cognitive behavioural treatment (CBT) for weight management has been used to improve compliance. Cognitive Behavioural Treatment (CBT) is the oldest and most studied behaviour change theory used in nutrition counseling and should be used for weight management in patients with overweight and obesity. The aim of this work is systematically review the drop-out rate and predictive factors associated with dropout from CBT for adults with overweight. Methods: The search was carried out in PubMed, Scopus and the Cochrane Library and conducted with the terms “patient dropouts”, “weight loss”, “diet, reducing”, “weight loss therapy”, “diet therapy”. Papers meeting the specified inclusion criteria were included in the qualitative analysis: the risk of bias was assessed using the RoB 2.0 Cochrane tool and the quality of evidence using the MMAT system. Results: The data from the 37 articles selected shows an overall drop-out rate between 5% and 62%. The predictive factors associated with attrition can be distinguished by demographics (younger age, educational status, unemployed status, and ethnicity) and psychological variables (greater expected 1-year Body Mass Index loss, previous weight loss attempts, perceiving more stress with dieting, weight and shape concerns, body image dissatisfaction, higher stress, anxiety, and depression). Common reasons for dropping out were objective (i.e., long-term sickness, acute illness, and pregnancy), logistical, poor job conditions or job difficulties, low level of organisation, dissatisfaction with the initial results, and lack of motivation. According to the Mixed Methods Appraisal quality analysis, 13.5% of articles were classified as five stars, and none received the lowest quality grade (1 star). The majority of articles were classified as 4 stars (46%). At least 50% of the selected articles exhibited a high risk of bias. The domain characterised by a higher level of bias was that of randomisation, with more than 60% of the articles having a high risk of bias. The high risk of bias in these articles can probably depend on the type of study design, which, in most cases, was observational and non-randomised. Conclusion: These findings demonstrate that CBT is effective for treatment of adults with obesity, achieving, in most cases, lower drop-out rates than other non-behavioural interventions. However, more studies should be conducted to compare different treatment strategies, as there is heterogeneity in the dropout assessment and the population studied. Ultimately, gaining a deeper understanding of the comparative effectiveness of these treatment strategies is of great value to patients, clinicians, and healthcare policymakers.