Modelled Weight Loss in an English Population Eligible for Bariatric Surgery: A Retrospective Open Cohort Study.

Introduction: In this study, we aimed to quantify the economic consequences of limited access to obesity treatment and estimate the effect of modelled weight loss in a population who were eligible for bariatric surgery.

Methods: This was a retrospective open cohort study using data from the Discover database (1 January 2010-31 December 2019). Index was the first day that individuals were aged ≥ 18 years and eligible for bariatric surgery [body mass index (BMI) ≥ 40.0 kg/m² (obesity class III), or 35.0-39.9 kg/m² (obesity class II) and an obesity-related complication]. Time to surgery, healthcare costs and the impact of modelled weight loss over 2 years on estimated healthcare costs were assessed.

Results: In total, 137,184 individuals were eligible for bariatric surgery, of whom 3241 (2.4%) ultimately received surgery during follow-up. Individuals who received surgery were slightly younger, and were more likely to be women and white, than the population eligible for surgery. Overall, 36.6% of individuals underwent surgery ≥ 4 years after they became eligible. Mean annual per-person healthcare costs increased 75% between year 1 and year 8 of the period before surgery in this group [from 1150 British pound sterling (GBP) to 2013 GBP]. Modelled weight loss of 10% would result in 58.3% of eligible individuals transitioning to obesity class I after 2 years, with only 12.2% remaining in obesity class III, resulting in a 14.3% reduction in healthcare costs. Greater degrees of weight loss were associated with greater estimated reductions in BMI and cost.

Conclusion: Delays to prompt weight management support appear to be associated with increasing healthcare costs, which could be mitigated by improving access to weight management.