Obesity Surgery—Weight Loss, Metabolic Changes, Oncological Effects, and Follow-Up

Abstract

Background: In 2017, the prevalence of obesity (BMI ≥= 30 kg/m2) in Germany was approximately 16%. Obesity increases an individual's risk of developing type 2 diabetes (T2DM) and arterial hypertension; it also increases overall mortality. Consequently, effective treatment is a necessity. Approximately 20 000 bariatric operations are performed in Germany each year.

Methods: This review is based on pertinent publications retrieved by a selective search in the PubMed and Cochrane databases and on current German clinical practice guidelines.

Results: The types of obesity surgery most commonly performed in Germany, Roux-en-Y gastric bypass and sleeve gastrectomy, lead to an excess weight loss of 27-69% ≥= 10 years after the procedure. In obese patients with T2DM, the diabetes remission rate ≥= 10 years after these procedures ranges from 25% to 62%. Adjusted regression analyses of data from large registries have shown that the incidence of malignancies is 33% lower in persons who have undergone obesity surgery compared to control subjects with obesity (unadjusted incidence 5.6 versus 9.0 cases per 1000 person-years). The operation can cause vitamin deficiency, surgical complications, gastroesophageal reflux, and dumping syndrome. Therefore, lifelong follow-up is necessary.

Conclusion: In view of an increasing number of patients undergoing bariatric surgery, it will probably not be feasible in the future for lifelong follow-up to be provided exclusively in specialized centers.

Figure:

Surgical procedures in obesity and metabolic surgery (Dr. Leven Efe, courtesy of the International Federation for the Surgery of Obesity and Metabolic Disorders [IFSO]). (e44) a) Sleeve gastrectomy (SG) with the removal of 80–90% of the stomach along an inserted calibration tube (diameter 1.2–1.5 cm). The resected stomach part is removed. Sleeve Gastrectomy is the most commonly performed type of obesity surgery in Germany (approximately 50% of operations for obesity). b) Roux-en-Y gastric bypass (RYGB): A small, elongated gastric pouch (20–30 mL) is created and directly connected to the small intestine via Roux-en-Y reconstruction. The lengths of the resulting biliopancreatic (green) and alimentary (yellow) limbs are variable; typically, the alimentary limb is 150 cm long, and the biliopancreatic limb 50 cm long. This results in hypoabsorption, but not malabsorption. Gastric bypass is the second most common type of obesity surgery in Germany (circa 32% of all procedures for obesity). It is surgically reversible, as it does not involve the resection of any part of the bowel or stomach. c) One-anastomosis gastric bypass (OAGB): a gastric pouch is formed that is similar to the one made in RYGB, but slightly longer. The small intestine is then anastomosed to the stomach as an omega loop. The biliopancreatic (green) limb is typically 150–250 cm long, although numerous variations have been described. OAGB accounts for approximately 15% of the surgical procedures for obesity that are performed in Germany. d) Gastric banding (LAGB): The gastric band is placed just below the gastroesophageal junction and connected to a subcutaneously implanted port. With this port, the degree of filling of the inner cushion of the gastric band, and thus the inner diameter of the band, can be regulated from the outside. Because of its many complications, and its lesser effect on weight than other types of obesity surgery, gastric banding is now only used in special situations (ca. 1% of procedures in Germany). e) Duodenal switch (BPD-DS): In this operation, sleeve gastrectomy is combined with duodenum division distal to the pylorus. Reconstruction of the passage is basically analogous to RYGB, although the loop lengths are markedly different: the alimentary limb is approx. 250 cm long, and the common distal segment (common channel) is 75–100 cm long. The biliopancreatic loop, which is usually not measured, is several meters long. Because the common channel is so short, the duodenal switch leads to marked hypoabsorption, in turn necessitating parenteral vitamin supplementation and leading to frequent, mushy stools. Few procedures of this type are performed in Germany (about 0.5% of all operations).