Is Bariatric Surgery Cost Effective?

| March 1, 2015

This column is written by medical students and is dedicated to reviewing the science behind obesity and bariatric surgery.

Column Editor: Daniel B. Jones, MD, MS, FACS
Professor of Surgery, Harvard Medical School, Vice Chair, Beth Israel Deaconess Medical Center, Boston, Massachusetts

This month: Is Bariatric Surgery Cost Effective?
by Benjamin N. Rome, Medical Student, Harvard Medical School, , Boston, Massachusetts

Bariatric Times. 2015;12(3):8–10.

Introduction
One-third of adults in the United States are obese.[1] Obesity is associated with significantly increased morbidity, mortality, and healthcare costs, due in part to its many associated comorbidities, including heart disease, diabetes, hypertension, and certain cancers.[2]  Bariatric surgery is effective at promoting sustained weight loss and reducing obesity-related comorbidities, especially type 2 diabetes mellitus (T2DM).[3] In addition, recent studies have found that patients who undergo bariatric surgery have reduced long-term mortality.[4,5]
There is widespread interest in understanding whether bariatric surgery is cost effective. Do surgical weight loss procedures offer good value for money? In assessing cost-effectiveness, studies must determine whether the surgical cost and risk of operative complications are outweighed by the potential benefits of sustained weight loss—increased life expectancy, improved quality of life, and lower lifetime medical costs due to reductions in obesity-related comorbidities.

REVIEW OF PAST RESEARCH
Several studies have evaluated the cost-effectiveness of bariatric surgery, most of which utilize modeling techniques that incorporate data from a variety of published literature to estimate the cost and quality-adjusted life expectancy of patients with obesity who undergo bariatric surgery compared to those who do not. In general, modeling studies have found that surgical interventions are cost effective for treating patients with obesity with incremental cost effectiveness ratios (ICERs) ranging from $1,000 to $40,000 per quality-adjusted life year (QALY) gained.[6]

Modeling studies have evaluated the cost effectiveness of Roux-en-Y gastric bypass (RYGB) and laparoscopic adjustable gastric banding (LAGB), with several studies showing that both procedures are cost effective in patients with severe obesity over a period of 20 plus years, and LAGB is effective even in patients with moderate obesity.[3,7,8] Some studies even found that weight loss surgery is cost effective in relatively healthy patients with a body mass index (BMI) below 40kg/m2 (the traditional threshold for offering weight loss surgery), though these groups did have higher ICERs than patients with severe obesity (BMI>40kg/m[2]) and those with obesity-related comorbidities.[3,9,10]

Several studies have found that bariatric surgery is more effective over the long term than over the short term, suggesting that the long-term benefits of surgical weight loss are an important factor in making the procedures cost effective.[3,11,12] For example, McEwen et al[12] used cost and quality of life data from a cohort of over 200 gastric bypass patients and found that bypass was moderately cost effective two years after surgery, with an ICER of $48,662 per QALY; however, extrapolating these data over the lifetime, bypass was significantly more cost-effective with an ICER of only $1,425 per QALY.

In addition, several studies have evaluated the cost effectiveness of bariatric surgery as a treatment for T2DM, based on clinical data that show more than half of patients achieve T2DM remission following gastric bypass and adjustable gastric banding procedures.[6,10]

Consequently, modeling studies have found that bariatric surgery is a cost-effective treatment for T2DM in patients with obesity.[3,10] Studies from Europe and Australia have even suggested that bariatric surgery may be a cost-saving treatment for T2DM with lower long-term healthcare costs and better health outcomes in patients who undergo surgery compared to those who do not.[11,13]

Despite the promising results of modeling studies, some recent clinical studies have not found that bariatric surgery leads to reduced annual healthcare costs, even over a 20-year period.[14–16] Cost data from the Swedish Obese Subjects study showed that while bariatric surgery patients had lower prescription drug costs (due largely to the lower cost of treating diabetes and cardiovascular disease), surgical patients did use significantly more inpatient and outpatient healthcare resources in the six years following surgery, with no difference in overall healthcare costs between the surgical and nonsurgical groups over 20 years.[15] However, the results of this study are limited by the fact that two-thirds of the bariatric surgery patients in the Swedish cohort underwent vertical banded gastropathy, a procedure that is no longer commonly performed.15 Similarly, Weiner et al[16] compared 30,000 bariatric surgery patients to matched controls and found that overall costs were similar in the six years following surgery, with bariatric surgery patients incurring more inpatient costs and fewer outpatient and drug costs.[16] In contrast, a smaller study of 194 patients who underwent gastric bypass found that annual healthcare costs decreased significantly in the bypass group in the three years following surgery.[17]

GAPS IN KNOWLEDGE
While many studies have evaluated the cost effectiveness of bariatric surgery as a treatment for obesity and T2DM, there are several gaps in the literature that require future study.
First, cost-effectiveness studies are predominately performed using modeling techniques that extrapolate 3 to 5 years of clinical data to estimate 50 or more years of patient costs and clinical outcomes.[18] Such studies require assumptions beyond the published data, leading to uncertainty and variation between studies. As more long-term data emerge about the costs and clinical benefits of bariatric surgery, modeling will be able to more accurately predict cost effectiveness. However, nearly all modeling studies to date demonstrate that bariatric surgery is cost effective in the long term, suggesting these results may be robust to a variety of modeling techniques and assumptions.[6]

Studies that do directly measure healthcare costs from clinical studies have not found that bariatric surgery leads to decreased healthcare costs.[14–16] These data suggest that the benefits of bariatric surgery in reducing costs may be overestimated by modeling studies. However, such findings do not preclude bariatric surgery from being cost effective, as the benefits in mortality and quality of life may be worth the added expense of surgery even if long-term healthcare costs are not reduced. More clinical outcomes and cost data are needed to inform future cost-effectiveness analyses.

Alternately, several modeling studies have suggested that bariatric surgery may be cost effective even in groups of patients to whom it is not currently offered —relatively healthy patients with class 1 or 2 obesity (BMI 30–39kg/m2).[3,9,10] These data are in line with recent studies suggesting that the BMI threshold for offering weight loss surgery should be lowered due to excellent outcomes and a survival benefit compared to nonsurgical weight management.19 More long-term clinical and cost data are needed on this patient population to help inform whether the indications for bariatric surgery should be expanded.

Most past studies have focused on direct healthcare costs and do not take into account indirect costs of obesity and obesity-related comorbidities, such as decreased work productivity and time missed at work. These indirect costs may dramatically affect the value of surgical weight loss procedures.[6,20,21] Consequently, past studies may underestimate the long-term cost reductions after bariatric surgery by limiting their analyses to direct healthcare costs.

Past studies have not evaluated the effect of hospital and surgeon volume, factors that influence operative costs and complication rates, which may have an effect on cost effectiveness.[6,22] Therefore, it is possible that the cost effectiveness of weight loss surgery may vary based on where the procedure performed.

Finally, nearly all of the bariatric surgery cost-effectiveness studies to date have focused on RYGB and LAGB, and no studies have evaluated the cost effectiveness of laparoscopic sleeve gastrectomy (LSG), which has become one of the most commonly performed bariatric surgical procedures in recent years. LSG has weight loss and T2DM remission rates between LAGB and RYGB, with fewer postoperative complications than bypass.[23–26] Thus, it is likely that cost-effectiveness models of LSG would mirror findings from the other two procedures, but future studies are warranted as LSG grows in popularity.

CONCLUSION
Many studies have found that RYGB and LAGB are cost-effective treatment options for patients with obesity, particularly those with T2DM. Some studies suggest that bariatric surgery may not lead to lower annual healthcare costs, but significant long-term reductions in morbidity and mortality caused by obesity may still render these procedures cost effective. Additional long-term clinical outcomes and cost data of patients undergoing bariatric surgery will allow for more accurate cost-effectiveness modeling. Future studies should evaluate the cost effectiveness of sleeve gastrectomy, include both direct and indirect costs related to obesity, and consider the effects of surgeon and hospital volume on cost effectiveness.

References
1.    May AL, Freedman D, Sherry B, Blanck HM. Obesity—United States, 1999–2010. MMWR Surveill Summ. 2013;62 Suppl 3:120–128. http://www.ncbi.nlm.nih.gov/pubmed/24264501. Accessed December 11, 2014.
2.     Richards NG, Beekley AC, Tichansky DS. The economic costs of obesity and the impact of bariatric surgery. Surg Clin North Am. 2011;91(6):1173–1180, vii–viii.
3.     Picot J, Jones J, Colquitt JL, et al. The clinical effectiveness and cost-effectiveness of bariatric (weight loss) surgery for obesity: a systematic review and economic evaluation. Health Technol Assess. 2009;13(41):1–190, 215–357, iii–iv.
4.     Adams TD, Gress RE, Smith SC, et al. Long-term mortality after gastric bypass surgery. N Engl J Med. 2007;357(8):753–761.
5.     Sjöström L, Narbro K, Sjöström CD, et al. Effects of bariatric surgery on mortality in Swedish obese subjects. N Engl J Med. 2007;357(8):741–752.
6.     Padwal R, Klarenbach S, Wiebe N, et al. Bariatric surgery: a systematic review of the clinical and economic evidence. J Gen Intern Med. 2011;26(10):1183–1194.
7.     Craig BM, Tseng DS. Cost-effectiveness of gastric bypass for severe obesity. Am J Med. 2002;113(6):491-498. http://www.ncbi.nlm.nih.gov/pubmed/12427499. Accessed December 9, 2014.
8.     Salem L, Devlin A, Sullivan SD, Flum DR. Cost-effectiveness analysis of laparoscopic gastric bypass, adjustable gastric banding, and nonoperative weight loss interventions. Surg Obes Relat Dis. 2008;4(1):26–32.
9.     Chang S-H, Stoll CRT, Colditz G a. Cost-effectiveness of bariatric surgery: should it be universally available? Maturitas. 2011;69(3):230–238.
10.     Hoerger TJ, Zhang P, Segel JE, Kahn HS, Barker LE, Couper S. Cost-effectiveness of bariatric surgery for severely obese adults with diabetes. Diabetes Care. 2010;33(9):1933–1939. doi:10.2337/dc10-0554.
11.     Keating CL, Dixon JB, Moodie ML, et al. Cost-effectiveness of surgically induced weight loss for the management of type 2 diabetes: modeled lifetime analysis. Diabetes Care. 2009;32(4):567–574.
12.     McEwen LN, Coelho RB, Baumann LM, Bilik D, Nota-Kirby B, Herman WH. The cost, quality of life impact, and cost-utility of bariatric surgery in a managed care population. Obes Surg. 2010;20(7):919–928.
13.     Ackroyd R, Mouiel J, Chevallier J-M, Daoud F. Cost-effectiveness and budget impact of obesity surgery in patients with type-2 diabetes in three European countries. Obes Surg. 2006;16(11):1488–1503.
14.     Maciejewski ML, Livingston EH, Smith VA, Kahwati LC, Henderson WG, Arterburn DE. Health expenditures among high-risk patients after gastric bypass and matched controls. Arch Surg. 2012;147(7):633–640.
15.     Neovius M, Narbro K, Keating C, et al. Health care use during 20 years following bariatric surgery. JAMA. 2012;308(11):1132–1141.
16.     Weiner JP, Goodwin SM, Chang H-Y, et al. Impact of bariatric surgery on health care costs of obese persons: a 6-year follow-up of surgical and comparison cohorts using health plan data. JAMA Surg. 2013;148(6):555–562.
17.     Sussenbach SP, Padoin a V, Silva EN, et al. Economic benefits of bariatric surgery. Obes Surg. 2012;22(2):266–270.
18.     Wang BCM, Furnback W. Modelling the long-term outcomes of bariatric surgery: a review of cost-effectiveness studies. Best Pract Res Clin Gastroenterol. 2013;27(6):987–995.
19.     Choudhury R a, Murayama KM, Neylan CJ, et al. Re-examining the BMI Threshold for Bariatric Surgery in the USA. J Gastrointest Surg. 2014;18(12):2074–2079.
20.     Ewing BT, Thompson M a, Wachtel MS, Frezza EE. A cost-benefit analysis of bariatric surgery on the South Plains region of Texas. Obes Surg. 2011;21(5):644–649.
21.     Terranova L, Busetto L, Vestri A, Zappa MA. Bariatric surgery: cost-effectiveness and budget impact. Obes Surg. 2012;22(4):646–653.
22.     Jacobsen HJ, Bergland a, Raeder J, Gislason HG. High-volume bariatric surgery in a single center: safety, quality, cost-efficacy and teaching aspects in 2,000 consecutive cases. Obes Surg. 2012;22(1):158–166.
23.     Li JF, Lai DD, Ni B, Sun KX. Comparison of laparoscopic Roux-en-Y gastric bypass with laparoscopic sleeve gastrectomy for morbid obesity or type 2 diabetes mellitus: a meta-analysis of randomized controlled trials. Can J Surg. 2013;56(6):E158–E164.
24.     Zhang Y, Ju W, Sun X, et al. Laparoscopic sleeve gastrectomy versus laparoscopic Roux-en-Y gastric bypass for morbid obesity and related comorbidities: A meta-analysis of 21 studies. Obes Surg. 2015;25(1):19–26.
25.     Zhang C, Yuan Y, Qiu C, Zhang W. A meta-analysis of 2-year effect after surgery: laparoscopic Roux-en-Y gastric bypass versus laparoscopic sleeve gastrectomy for morbid obesity and diabetes mellitus. Obes Surg. 2014;24(9):1528–1535.
26.     Wang S, Li P, Sun XF, Ye NY, Xu ZK, Wang D. Comparison between laparoscopic sleeve gastrectomy and laparoscopic adjustable gastric banding for morbid obesity: a meta-analysis. Obes Surg. 2013;23(7):980–986.

FUNDING: No funding was provided.

FINANCIAL DISCLOSURES: The author reports no conflicts of interest relevant to the content of this article.

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