Comparing effects of obesity treatment with very low energy diet and bariatric surgery after 2 years: a prospective cohort study

Abstract

Objectives: To compare long-term effects and complications of medical treatment (MT) of obesity including very low energy diet with bariatric surgery.

Design and setting: This prospective study conducted in a clinical setting recruited individuals with body mass index (BMI) ≥35 kg/m² referred for obesity treatment. Demographic and anthropometric data, laboratory samples, and questionnaire replies were collected at baseline and 2 years.

Participants and interventions: 971 individuals were recruited 2015-2017. 382 received MT, 388 Roux-en-Y gastric bypass (RYGB) and 201 sleeve gastrectomy (SG).

Main outcome measures: Primary outcomes included changes in anthropometric measures, metabolic variables and safety. These were analysed using a linear regression model. A logistic regression model was used to analyse composite variables for treatment success (secondary outcomes). A random forest (RF) model was used to examine the importance of 15 clinical domains as predictors for successful treatment.

Results: Two-year data were available for 667 individuals (68.7%). Regarding primary outcomes, the decrease in excess BMI was 27.5%, 82.5% and 70.3% and proportion achieving a weight of >10% was 45.3%, 99.6% and 95.6% for MT, RYGB and SG, respectively (p<0.001). The groups were comparable regarding levels of vitamins, minerals and haemoglobin or safety measures. Likelihood for success (secondary outcome) was higher in the surgical groups (RYGB: OR 5.3 (95% CI 3.9 to 7.2) vs SG: OR 4.3 ((95% CI 3.0 to 6.2)) in reference to MT. Baseline anthropometry had the strongest predictive value for treatment success, according to the RF model.

Conclusions: In clinical practice, bariatric surgery by RYGB or SG is most effective, but meaningful weight loss is achievable by MT with strict caloric restriction and stepwise introduction of a normal diet. All treatments showed positive effects on well-being, cardiovascular risk factors, and levels of vitamins and minerals at 2-year follow-up and groups were similar regarding safety measures.

Trial registration number: NCT03152617.

Keywords: adult surgery; diabetes & endocrinology; nutrition & dietetics.

Figure 1

Changes in clinical variables presented as estimated means with 95% CIs. Missing data patterns, before and after imputation with multiple imputation by chained equations. AUDIT, Alcohol Use Disorders Identification Test; BAI, Beck Anxiety Inventory; BE, binge eating; BN, bulimia nervosa; BNC, bulimia nervosa with compensatory behaviour; CR, cognitive restraint; EE, emotional eating; EQ-5D, EuroQol Five-Dimensional Questionnaire; MT, medical Treatment; PHQ-9, Patient Health Questionnaire-9; QEWPR, Questionnaire on eating and weight patterns, revised; RYGB, Roux-en-Y gastric bypass; SG, sleeve gastrectomy; SGQ, Saltin Grimby Questionnaire; TFEQ, three-Factor Eating Questionnaire; UE, uncontrolled eating.

Figure 2

Likelihood for successful or unsuccessful treatment. Successful treatment is defined as as a decrease in excess body mass index (BMI) of at least 50% or a BMI of less than 30 kg/m² at 2-year follow-up without the need for surgical treatment or hospital ward during the follow-up period. Unsuccessful treatment is defined as a loss of less than 25% of excess BMI (EBMI) or the need for surgical or hospital ward during the follow-up period. MT, medical treatment; RYGB, Roux-en-Y gastric bypass; SG, sleeve gastrectomy.

Figure 3

Predictive value of 15 clinical domains on the success of obesity treatment (A) and for different treatment groups (B–D). ADHD, attention-deficit/hyperactivity disorder; ALAT, alanine aminotransferase; ASAT, aspartate aminotransferase; AUDIT, Alcohol Use Disorders Identification Test; BAI, Becks Anxiety Inventory; BMI, body mass index; CV, cardiovascular; DM, diabetes mellitus; EQ-5D, EuroQol Five-Dimensional Questionnaire; HbA1c, glycated haemoglobin; HDL, high density lipoprotein; IHD, ischaemic heart disease; LDL, low-density lipoprotein; PHQ-9, Patient Health Questionnaire-9; PPI, proton-pump inhibitors; QEWP, Questionnaire on Eating and Weight Patterns; SGQ, Saltin Grimby Questionnaire; T4, thyroxine; TFEQ, Three-Factor Eating Questionnaire; TG, triglycerides; TSH, thyroid-stimulating hormone; VTE, venous thromboembolism.