Pre-surgical factors related to latent trajectories of 5-year weight loss for a diverse bariatric surgery population.

BACKGROUND: Analyzing trajectories of weight loss may address how particular groups of patients respond to metabolic and bariatric surgery. OBJECTIVES: The Bariatric Experience Long Term (BELONG) study was designed to use a theoretical model to examine determinants of weight loss and recurrence. SETTING: Large integrated health system in Southern California with 11 surgical practices and 23 surgeons. METHODS: A total of n = 1338 patients who had metabolic and bariatric surgery were surveyed before surgery to measure factors related to median percent total weight loss (%TWL) over 5 years. Longitudinal weight data were available for n = 1024 (76.5% of the sample). Data were analyzed using latent growth mixture models (GMM) to estimate trajectories of weight change separately for gastric sleeve and bypass operations. These trajectories were then described using relevant variables from the baseline survey. RESULTS: For both gastric sleeve (n = 733) and bypass (n = 291) operations, 3 latent trajectories of median %TWL were found corresponding to most, moderate, and least %TWL. Sleeve trajectories were distinguished by body mass index at surgery and geocoded environmental factors. Bypass trajectories varied by self-reported and geocoded environmental factors, comorbidity burden, race, experiential avoidance, and weight control strategies. CONCLUSIONS: Future research should examine the role of the built and perceived environment in surgical weight loss. Bariatric practices should focus less on the presurgical period for predictors of long-term weight loss and begin efforts to monitor real-time patient-reported outcomes to help tailor intervention strategies for patients who either do not lose an expected amount of weight or who begin to experience weight recurrence.

Cohort profile: The Bariatric Experience Long Term (BELONG): a long-term prospective study to understand the psychosocial, environmental, health and behavioural predictors of weight loss and regain in patients who have bariatric surgery.

PURPOSE: The Bariatric Experience Long Term (BELONG) prospective study cohort was created to address limitations in the literature regarding the relationship between surgical weight loss and psychosocial, health, behaviour and environmental factors. The BELONG cohort is unique because it contains 70% gastric sleeve and 64% patients with non-white race/ethnicity and was developed with strong stakeholder engagement including patients and providers. PARTICIPANTS: The BELONG cohort study included 1975 patients preparing to have bariatric surgery who completed a baseline survey in a large integrated health system in Southern California. Patients were primarily women (84%), either black or Hispanic (59%), with a body mass index (BMI) of 45.1±7.4 kg/m2, age 43.3±11.5 years old, and 32% had at least one comorbidity. FINDINGS TO DATE: A total of 5552 patients were approached before surgery between February 2016 and May 2017, and 1975 (42%) completed a baseline survey. A total of 1203 (73%) patients completed the year 1 and 1033 (74%) patients completed the year 3 postoperative survey. Of these survey respondents, 1341 at baseline, 999 at year 1, and 951 at year 3 were included in the analyses of all survey and weight outcome data. A total of 803 (60% of eligible patients) had survey data for all time points. Data collected were self-reported constructs to support the proposed theoretical model. Height, weight and BMI were abstracted from the electronic medical record to obtain the main outcomes of the study: weight loss and regain. FUTURE PLANS: We will collect self-reported constructs and obtain height, weight and BMI from the electronic medical record 5 years after bariatric surgery between April 2022 and January 2023. We will also collect patient experiences using focus groups of 8-12 patients each throughout 2022.