Costs of bariatric surgery in a randomised control trial (RCT) comparing Roux en Y gastric bypass vs sleeve gastrectomy in morbidly obese diabetic patients.

Aim: To provide a longitudinal analysis of the direct healthcare costs of providing laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB) surgery service in the context of a randomised control trial (RCT) of obese patients with type 2 diabetes in Waitemata District Health Board, Auckland, New Zealand.

Methods: The Waitemata District Health Board costing system was used to calculate costs in New Zealand Dollars (NZD) associated with all pre- and post-operative hospital clinic visits, peri-operative care, hospitalisations and medication costs up to one year after bariatric surgery. Healthcare costs of medications, laboratory investigations and hospital clinic visits for one year prior to enrolment into the RCT were also calculated.

Results: One hundred and fourteen patients were randomised to undergo laparoscopic sleeve gastrectomy (LSG, n=58) or laparoscopic Roux en Y gastric bypass (LRYGB, n=56). Total costs one year pre-enrolment was $203,926 for all patients (mean $1,789 per patient). Total cost of surgery was $1,208,005 (mean $9,131 per LSG patient and mean $12,456 per LRYGB patient). Total cost one year post-operatively was $542,656 (mean $4,760 per patient). The total medication cost reduced from $118,993.72(mean $1,044 per patient) to $31,304.93 (mean $274.60 per patient), p<0.005. The largest cost reduction was seen with annual diabetic medications reducing from $110,115.78(mean $965.93 per patient) to $7,237.85 (mean $63.48 per patient), p<0.005.

Conclusions: Among patients with type 2 diabetes and morbid obesity undergoing LSG and LRYGB, health service costs were greater in the year after surgery than in the year before, although prescription costs were lower post-operatively. There was no significant difference in reduction in prescription cost by surgical procedure at 12 months. However, the LRYGB surgery was more expensive than LSG, primarily because of the longer operative time required.