The American College of Surgeons and accreditation of metabolic surgery

The American College of Surgeons (ACS) has long been involved in the field of metabolic and bariatric surgery. Some of the important milestones in this field over the last two decades include the development of the laparoscopic approach to bariatric surgery, which led to exponential growth in the annual number of bariatric operations; improved training, including development of fellowship programs in bariatric surgery; initiation of the centers of excellence (COE) concept;  Centers for Medicare & Medicaid Services (CMS) coverage of bariatric surgery; and the transition from the concept and terminology of bariatric surgery to that of metabolic surgery. The ACS has played a supportive role in the attainment of most of these important milestones, and some of these developments are reviewed herein, particularly the establishment of an accreditation system that led to improvement in the quality and care of metabolic surgery recipients nationwide.

Metabolic bariatric surgery: A durable treatment for obesity

Severe obesity is a chronic metabolic disorder that leads to a multitude of serious diseases, including diabetes, hypertension, dyslipidemia, coronary artery disease, cardiomyopathy, fatty liver disease, obstructive sleep apnea, pulmonary hypertension, gout, venous stasis diseases, and cancer, to name but a few. Obesity and the spectrum of related comorbidities are best treated by early intervention. However, current medical therapies offered as the primary treatment for severe obesity have proven to have poor long-term effects. Metabolic bariatric surgery is performed within the context of a multidisciplinary support structure that includes dietary and psychological support, rehabilitation, metabolic reinforcement, long-term medical weight-loss maintenance support, and late surgical body contouring. Metabolic bariatric surgery is, at present, the most effective and durable therapy for the treatment of severe obesity.

In 2013, the American Medical Association (AMA) recognized obesity as a disease.1 Recognition of obesity as a complex of diseases, including type 2 diabetes mellitus (T2DM) and heart disease, has contributed to the development of the more inclusive discipline of metabolic surgery, which uses bariatric surgery to treat obesity and its comorbidities.

Laparoscopic bariatric surgery

The laparoscopic approach to Roux-en-Y gastric bypass (RYGB) was first described by Wittgrove and colleagues in 1994.2 This minimally invasive approach was adopted by bariatric surgeons and was responsible for exponential growth in the number of bariatric operations performed in the U.S. between 1999 and 2003.3 In the same period, the number of bariatric surgeons with membership in the American Society for Metabolic and Bariatric Surgery (ASMBS) increased from 258 in 1998 to 631 members in 2002.3 ASMBS membership climbed to 1,819 members in 2008.4

During the rapid growth in bariatric surgery, some surgeons attempted to perform the complex laparoscopic RYGB procedure with inadequate training. At the time, this lack of training raised questions regarding the quality and safety of bariatric surgery.5 Insurance companies denied coverage for laparoscopic bariatric procedures despite clearly documented benefits of the approach. Some of the motivation for these denials may have been financial, given the large increase in operations being performed. Individual third-party payors, such as Blue Cross and Blue Shield, initiated their own COE programs to improve the quality of care for patients undergoing bariatric surgery. Shortly thereafter, other insurers initiated proprietary COE programs. An overarching bariatric surgery accreditation program was needed. A major tenet of the COE concept has been the demonstrated relationship between hospital case volume and outcomes. Numerous studies have reported improved outcomes in association with bariatric surgery performed at high-volume centers.5-8

Case volume and outcome relationship in bariatric surgery

Bariatric surgery, particularly the laparoscopic RYGB, is a complex operation performed in a high-risk population with many associated comorbidities. One factor that has been associated with improved outcomes is higher annual hospital and surgeon case volume. The inverse volume and outcome relationship states that patients treated at high-volume centers tend to have lower morbidity and mortality than patients treated at low-volume centers.5 This relationship has been well described for other complex procedures, including esophageal resection, pancreas resection, repair of abdominal aortic aneurysm, and coronary artery bypass surgery. In a study examining 277,760 laparoscopic bariatric stapling procedures comparing the outcomes of low-volume (<50 cases annually) with high-volume centers (≥50 cases annually), Jafari and colleagues found significantly lower inhospital mortality at high-volume than low-volume centers (0.07 percent versus 0.17 percent, respectively).6 In a study of academic centers, Nguyen and colleagues examined bariatric surgery outcomes according to low, moderate, or high annual hospital volume and found that RYGB cases performed at high-volume hospitals (>100 cases annually) had shorter patient hospital stays, lower complication and inhospital death rates, and lower costs compared with low-volume hospitals.7 Similarly, in a systematic literature review, Zevin and colleagues found a strong correlation between higher annual hospital volume and improved patient outcomes in 14/17 studies.8

Development of an accreditation system in bariatric surgery

To improve the safety and quality of bariatric surgery and in response to the initiation of COE programs by insurers, the ASMBS initiated the bariatric surgery COE program in 2004. The ACS initiated its own accreditation program in 2005, the Bariatric Surgery Center Network (BSCN).9 The original ASMBS COE had 10 accreditation criteria, including institutional commitment to education; facility volume of 25 or more cases annually; a designated bariatric medical director; a full complement of consultative physician and critical care services; appropriate bariatric equipment and instruments; experienced bariatric surgeon(s); standardized care pathways; dedicated bariatric nurses; support group structure; and a system for long-term follow-up and data collection. The original ACS BSCN had two levels of designation: A Level 1 center must perform 25 or more operations annually and have two or more credentialed bariatric surgeons capable of managing complex bariatric patients; a Level 2 center required a lower case volume requirement (≥25 per year), but was limited to lower acuity patients (that is, patients with a lower body mass index, younger age, no elective revision cases, and so on).

In 2012, under former ASMBS president Robin P. Blackstone, MD, FACS, the ASMBS COE and the ACS BSCN bariatric surgery accreditation programs were unified into a single program, the Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program (MBSAQIP®). The MBSAQIP continues to focus on the need for institutional infrastructure and equipment to care for patients with morbid obesity, developing experienced staff and surgeons, and reporting of all bariatric operations, including revision cases. The program also established improved data point definitions and standardized data collection processes similar to that of the College’s National Surgical Quality Improvement Program (ACS NSQIP®), and encouraged local and regional collaboration to augment quality improvement.10

The MBSAQIP accreditation incorporates five center designations: comprehensive, low-acuity, comprehensive adolescent, ambulatory, and adolescent centers. The comprehensive designation is the most commonly requested level of accreditation. It requires the facility to be able to provide all approved bariatric procedures and 50 or more approved bariatric stapling procedures per year. A low-acuity center must perform 25 or more approved bariatric operations and primary procedures defined within the low-acuity restriction. Adolescent centers must comply with the adolescent standards. If the center performs 25 or more stapling procedures annually, the center must have a verified bariatric surgeon as a co-surgeon on each case. Ambulatory centers must perform an annual volume of 25 or more approved bariatric operations on low-acuity patients. At present, more than 700 U.S. and Canadian bariatric surgery centers are MBSAQIP-accredited.11

CMS coverage of bariatric surgery

CMS implemented a national coverage determination for bariatric surgery in 2006. This decision mandated that Medicare patients undergo bariatric surgery only at a designated COE. However, in September 2013, CMS removed this requirement because of concern over limiting access to care.12 Hence, Medicare patients may have bariatric surgery at any facility regardless of its accreditation. Despite this change in coverage, most private insurers continue to view bariatric surgery accreditation as a sign of quality.

Benefits of accreditation

The benefits of an accredited bariatric surgery program include the establishment of a uniform institutional structure, processes of care, and outcomes data collection to support continuous quality improvement. Furthermore, many studies have reported improved outcomes when bariatric surgery is performed at an accredited center.13-16

In one of the first articles examining the role of bariatric surgery accreditation, Nguyen and colleagues examined 35,284 RYGB operations performed at academic centers, finding that patients had shorter lengths of stay at accredited centers (by 0.3 days), lower mortality (0.06 percent at accredited versus 0.21 percent at nonaccredited centers), and lower cost (by $3,758) than at nonaccredited centers.13 In a study examining commercial claims, Kwon and colleagues reported that accredited centers had significantly lower inpatient mortality, complications, reoperations, and readmissions.14 Jafari and colleagues examined 277,760 laparoscopic bariatric stapling procedures (RYGB and sleeve gastrectomy), finding that accredited centers where 50 or more cases were performed per year had the lowest inhospital mortality compared with similar high-volume nonaccredited centers.6 The higher mortality at the high-volume, nonaccredited centers suggests that accreditation may be a factor independent from volume in achieving improved outcomes.

In another study, Morton and colleagues found that, when compared with accredited centers, nonaccredited centers had a higher mean length of stay (2.25 versus 1.99 days), higher total charges ($51,189 versus $42,212), a higher rate of complications (12.3 percent versus 11.3 percent), higher mortality (0.13 percent versus 0.07 percent), and a higher rate of “failure to rescue” (0.97 percent versus 0.55 percent).15 The failure-to-rescue concept represents the inability of the hospital and provider to rescue a patient from a bariatric complication likely because of a lack of center infrastructure and/or experienced staff and physicians in order to achieve early recognition and care of the complication.

Overall, mortality associated with bariatric surgery has declined significantly in the last two decades (see Figure 1). Initiation of the accreditation system is likely to have contributed to this positive change.16

Figure 1. Bariatric surgery inhospital mortality by year, 2002–2009

Figure 1. Bariatric surgery inhospital mortality by year, 2002–2009

Reprinted with permission from: Nguyen NT, Nguyen B, Smith B, et al. Proposal for a bariatric mortality risk classification system for patients undergoing bariatric surgery. Surg Obes Relat Dis. 2013;9(2):239-246.



The ACS has been integrally involved in metabolic and bariatric surgery and continues to support the field through its leadership, educational efforts, research, strengthening of the accreditation system, data acquisition and quality improvement, and advocacy for coverage of bariatric surgery. The College has expressed a commitment to continue to support this important subspecialty of general surgery. The value to patients of bariatric surgery accreditation within the field of metabolic surgery has been well demonstrated, cannot be overstated, and is here to stay.


This work was supported by the ACS. The authors declare that they have no relevant conflict of interest.

We are grateful to the ACS for their generous sponsorship of the Metabolic Surgery Symposium and associated journal publication development. We thank Jane N. Buchwald, chief scientific research writer, Medwrite Medical Communications, Maiden Rock, WI, for manuscript editing and publication coordination. And we thank Patrick Beebe and Donna Coulombe, ACS Executive Services, for their expert organization of the Metabolic Surgery Symposium.


  1. American Medical Association. House of Delegates Resolution 420: Recognition of obesity as a disease. Presented at: House of Delegates Annual Meeting; 2013. Available at: Accessed April 23, 2019.
  2. Wittgrove AC, Clark GW, Tremblay LG. Laparoscopic gastric bypass, Roux-en-Y: Preliminary report of five cases. Obes Surg. 1994;4(4):353-357.
  3. Nguyen NT, Root J, Zainabadi K, et al. Accelerated growth of bariatric surgery with the introduction of minimally invasive surgery. Arch Surg. 2005;140(12):1198-1202.
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  7. Nguyen NT, Paya M, Stevens CM, et al. The relationship between hospital volume and outcome in bariatric surgery at academic medical centers. Ann Surg. 2004;240(4):586-593.
  8. Zevin B, Aggarwal R, Grantcharov TP. Volume-outcome association in bariatric surgery: A systematic review. Ann Surg. 2012;256(1):60-71.
  9. Champion JK, Pories WJ. Centers of excellence for bariatric surgery. Surg Obes Relat Dis. 2005;1(2):148-151.
  10. Blackstone R, Dimick JB, Nguyen NT. Accreditation in metabolic and bariatric surgery: Pro versus con. Surg Obes Relat Dis. 2014;10(2):198-202.
  11. Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program. American College of Surgeons and American Society for Metabolic and Bariatric Surgery. Available at: Accessed April 8, 2019.
  12. Centers for Medicare & Medicaid Services. Decision memo for bariatric surgery for the treatment of morbid obesity—facility certification requirement (CAG-00250R3). Available at: Accessed April 23, 2019.
  13. Nguyen NT, Nguyen B, Nguyen VQ, et al. Outcomes of bariatric surgery performed at accredited vs nonaccredited centers. J Am Coll Surg. 2012;215(4):467-474.
  14. Kwon S, Wang B, Wong E, et al. The impact of accreditation on safety and cost of bariatric surgery. Surg Obes Relat Dis. 2013;9(5):617-622.
  15. Morton JM, Garg T, Nguyen N. Does hospital accreditation impact bariatric surgery safety? Ann Surg. 2014;260(3):504-508.
  16. Nguyen NT, Nguyen B, Smith B, et al. Proposal for a bariatric mortality risk classification system for patients undergoing bariatric surgery. Surg Obes Relat Dis. 2013;9(2):239-246.

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