Objectives:To present a comprehensive real-world micro-costing analysis of bariatric surgery.

Methods: Patients were included if they underwent primary bariatric surgery (gastric banding [GB], gastric bypass [GBP] and sleeve gastrectomy [SG]) between 2013 and 2019. Costs were disaggregated into cost items and average-per-patient costs from the Australian healthcare systems perspective were expressed in constant 2019 Australian dollars for the entire cohort and subgroup analysis. Annual population-based costs were calculated to capture longitudinal trends. A generalized linear model (GLM) predicted the overall bariatric-related costs.

Results: N = 240 publicly funded patients were included, with the waitlist times of ≤ 10.7 years. The mean direct costs were $11,269. The operating theatre constituted the largest component of bariatric-related costs, followed by medical supplies, salaries, critical care use, and labour on-costs. Average cost for SG ($12,632) and GBP ($15,041) was higher than that for GB ($10,049). Operating theatre accounted for the largest component for SG/GBP costs, whilst medical supplies were the largest for GB. We observed an increase in SG and a decrease in GB procedures over time. Correspondingly, the main cost driver changed from medical supplies in 2014-2015 for GB procedures to operating theatre for SG thereafter. GLM model estimates of bariatric average cost ranged from $7,580 to $36,633.

Conclusions: We presented the first detailed characterization of the scale, disaggregated profile and determinants of bariatric-related costs, and examined the evolution of resource utilization patterns and costs, reflecting the shift in the Australian bariatric landscape over time. Understanding these patterns and forecasting of future changes are critical for efficient resource allocation.