A randomised control trial assessing the impact of an investment-based intervention on weight-loss, glycated haemoglobin and psychological outcomes 1 year post bariatric surgery

Abstract

Background:  Whilst bariatric surgery remains the most effective form of weight management, some patients show less than optimal weight loss. This study evaluated the impact of focusing on the investment patients have made in surgery to improve health outcomes. Methods:  The study used a randomised control trial design with patients allocated either to the control or investment intervention group. Patients were recruited from University College Hospital, London and half were randomly allocated to the intervention arm and described the investment they had made in their operation just before surgery then 3 and 6 months post-surgery. The primary outcomes were patient’s weight, body mass index (BMI) and HbA1c at 12 months.  Secondary psychological outcomes were also assessed at baseline and 12 months. Results: By one year post-operation for 141 patients the mean change in weight was 35.2kg, for BMI it was 12.7 and for HbA1c it was 0.65.  At one year follow up there was no significant difference between groups for weight loss (kg and BMI) using both ITT analysis and explanatory analysis. Using explanatory analysis (n=119) a significant difference in HbA1c change was found with those in the control group showing a greater improvement in their blood sugars than those in the intervention group (5.44 vs 5.41; p=0.03).  Response rates for psychological outcomes were low (n=73).  No differences were found for most psychological outcomes, however, those in the intervention group reported lower levels of imposed control than those in the control group by 12 months.  Conclusions: Highlighting the patients’ investment pre and post bariatric surgery had no impact on weight loss as measured by kg or BMI 1 year later. Furthermore, no changes were found for most psychological outcomes. Some detrimental impacts were found however relating to HBA1c and perceptions of control.  ClinicalTrials.gov registration: NCT02045628