Kenric M. Murayama

Bariatric Surgery Outcomes

Obesity is associated with an increased risk of death, and morbid obesity carries a significant risk of life-threatening complications such as heart disease, diabetes, and high blood pressure. Bariatric surgery is recognized as the only effective treatment of morbid obesity. The estimated number of bariatric operations performed in the United States in 2008 was more than 13 times the number performed in 1992. Despite this increase, only 1% of the eligible morbidly obese population are currently treated with bariatric surgery.

GLP-1 Plays a Limited Role in Improved Glycemia Shortly After Roux-en-Y Gastric Bypass: A Comparison With Intensive Lifestyle Modification

Rapid glycemic improvements following Roux-en-Y gastric bypass (RYGB) are frequently attributed to the enhanced GLP-1 response, but causality remains unclear. To determine the role of GLP-1 in improved glucose tolerance after surgery, we compared glucose and hormonal responses to a liquid meal test in 20 obese participants with type 2 diabetes mellitus who underwent RYGB or nonsurgical intensive lifestyle modification (ILM) (n = 10 per group) before and after equivalent short-term weight reduction. The GLP-1 receptor antagonist exendin(9–39)-amide (Ex-9) was administered, in random order and in double-blinded fashion, with saline during two separate visits after equivalent weight loss. Despite the markedly exaggerated GLP-1 response after RYGB, changes in postprandial glucose and insulin responses did not significantly differ between groups, and glucagon secretion was paradoxically augmented after RYGB. Hepatic insulin sensitivity also increased significantly after RYGB. With Ex-9, glucose tolerance deteriorated similarly from the saline condition in both groups, but postprandial insulin release was markedly attenuated after RYGB compared with ILM. GLP-1 exerts important insulinotropic effects after RYGB and ILM, but the enhanced incretin response plays a limited role in improved glycemia shortly after surgery. Instead, enhanced hepatic metabolism, independent of GLP-1 receptor activation, may be more important for early postsurgical glycemic improvements.

Roux-en-Y gastric bypass compared with aggressive diet and exercise therapy for morbidly obese patients awaiting renal transplant: a decision analysis.

BACKGROUND The optimal management of morbidly obese patients awaiting renal transplant is controversial and unknown. The objective of this study was to compare the impact of Roux-en-Y gastric bypass (RYGB) versus diet and exercise on the survival of morbidly obese patients with end-stage renal disease awaiting renal transplant. METHODS A decision analytic Markov state transition model was designed to simulate the life of morbidly obese patients with end-stage renal disease awaiting transplant. Life expectancy after RYGB and after 1 and 2 years of diet and exercise was estimated and compared in the framework of 2 clinical scenarios in which patients above a body mass index (BMI) of 35 kg/m(2) or above a BMI of 40 kg/m(2) were ineligible for transplantation, reflecting the BMI restrictions of many transplant centers. In addition to base case analysis (45 kg/m(2) BMI preintervention), sensitivity analysis of initial BMI was completed. Markov model parameters were extracted from the literature. RESULTS RYGB improved survival compared with diet and exercise. Patients who underwent RYGB received transplants sooner and in higher frequency. Using 40 kg/m(2) as the upper limit for transplant eligibility, base case patients who underwent RYGB gained 5.4 years of life, whereas patients who underwent 1 and 2 years of diet and exercise gained 1.5 and 2.8 years of life, respectively. Using 35 kg/m(2) as the upper limit, RYGB base case patients gained 5.3 years of life, whereas patients who underwent 1 and 2 years of diet and exercise gained .7 and 1.5 years of life, respectively. CONCLUSIONS In morbidly obese patients with end-stage renal disease, RYGB may be more effective than optimistic weight loss outcomes after diet and exercise, thereby improving access to renal transplantation.

Determinants of surgical decision making: a national survey.

BACKGROUND We conducted a national survey of general surgeons to address the association between surgeon characteristics and the tendency to recommend surgery. METHODS We used a web-based survey with 25 hypothetical clinical scenarios with clinical equipoise regarding the decision to operate. The respondent-level tendency to operate (TTO) score was calculated as the average score over the 25 scenarios. Surgical volume was based on self-report. Linear regression models were used to evaluate the associations between TTO, other covariates of interest, and surgical volume. RESULTS There were 907 respondents. The mean surgical TTO was 3.05 ± .43. Surgeons had significantly lower TTO scores when responding to questions within their area of practice (P < .0001). There was no association between TTO and malpractice concerns, financial incentives, or compensation structure. CONCLUSIONS Surgeons recommend intervention far less frequently within their area of specialization. Malpractice concerns, volume, and financial compensation do not significantly affect surgical decision making.

Variation in the Utilization of Minimally Invasive Surgical Operations.

Objective: The goal of this study was to examine regional variation in use of minimally invasive surgical (MIS) operations. Summary Background Data: Regional variation exists in performance of surgical operations. Variation in the use of MIS has not been studied. Methods: Five operations that are performed open or MIS were selected: cholecystectomy, appendectomy, colectomy, antireflux, and bariatric. A 3-state database from 2008 to 2011 was used; states were divided into hospital service areas (HSAs). For each operation, the percentage of MIS operations was calculated. HSAs with less than 50% or more than 150% of the MIS average were considered outliers. Population demographics, geography, and hospital and physician presence were compared between HSAs. Rates of performance by patient disease and the presence of MIS surgeons were also investigated. Results: MIS cholecystectomy was performed with low variation; MIS appendectomy, antireflux, and bariatric operations with medium variation; and MIS colectomy with high variation. With the exception of MIS colectomy, there were no differences in the patient demographics, geography, or disease types treated with an MIS approach between HSAs with low-, non-, or high utilization of MIS. There is no correlation between the number of MIS surgeons and the percentage of procedures performed MIS. Conclusions: Variation in utilization of MIS exists and differs by operation. Patient demographics, patient disease, and the ability to access care are associated only with variation in use of MIS for colectomy. For all other operations studied, these factors do not explain variation in MIS use. Further investigation is warranted to identify and eliminate causes of variation.