Metabolic acuity score: effect on major complications after bariatric surgery

Surgery for Obesity and Related Diseases 6 (2010) 267–273

Original article

Metabolic acuity score: effect on major complications after bariatric surgery Robin P. Blackstone, M.D.a,b,*, Melisa C. Cortés, M.A.a a

Scottsdale Bariatric Center, Scottsdale, Arizona Department of Surgery, University of Arizona College of Medicine, Phoenix, Arizona Received May 31, 2009; revised September 10, 2009; accepted September 16, 2009

b

Abstract

Background: Co-morbid conditions in obese patients contribute to the incidence and severity of major complications after bariatric surgery and significantly increase the cost of the procedure. Previous publications have validated the patient factors that increase the risk of mortality; however, it is currently a rare event. The development of a metabolic acuity score (MAS) to augment the body mass index might allow for accurate preoperative assessment and optimal treatment of patients. The present study has proposed a MAS for decreasing major complications. Methods: Prospectively collected outcomes of 2416 patients undergoing Roux-en-Y gastric bypass (n ⫽ 1821) or laparoscopic adjustable gastric banding (n ⫽ 595) in a community hospital were evaluated for the incidence of major complications, readmissions, and reoperations. Beginning in August of 2006, 1072 patients were divided into MAS groups of 1– 4 according to age, body mass index, weight, history of deep vein thrombosis/pulmonary embolism, sleep apnea, diabetes, hypertension, immobility, heart disease, and psychological classification. The acuity groups were compared with each other and with 1344 patients who underwent treatment before the MAS was implemented. Results: A significant decrease occurred in the readmission rates within 30 days after the MAS was put into practice (8.5% before MAS versus 1.7% after MAS, P ⬍.001) for the Roux-en-Y gastric bypass patients. The postoperative infection rates were lower after implementing the MAS (3.5% before MAS, .7% after MAS, P ⬍.001). After adjusting for random and fixed effects of covariates, the implementation of the MAS significantly reduced the incidence of postoperative internal hernias, infections, deep vein thrombosis, readmissions, and reoperations. Conclusion: Recognition of specific patient acuity characteristics through the implementation of MAS and aggressive preoperative and perioperative management led to lower major complication rates and decreased the incidence of readmissions and reoperations after bariatric surgery. (Surg Obes Relat Dis 2010;6:267–273.) © 2010 American Society for Metabolic and Bariatric Surgery. All rights reserved.

Keywords:

Bariatric surgery; Risk adjustment; Acuity; Outcomes

To “do no harm” is part of our oldest medical tradition in the Hippocratic oath; however, in the modern era of surgery, it has been codified in the expectations of patients and payors that extremely complex procedures can be accom*Reprint requests: Robin P. Blackstone, M.D., F.A.C.S., Scottsdale Bariatric Center, 10200 North 92nd Street, Suite 225, Scottsdale, AZ 85258 E-mail: [email protected]

plished with no mortality and very little morbidity. This expectation is even greater for nonemergent cases. Data have shown that the obese patient has a high burden of metabolic disease [1]. These metabolic problems contribute to the incidence and severity of major complications after surgery [2]. The metabolic acuity score (MAS) has been introduced to augment the body mass index (BMI). It allows for a deliberate preoperative assessment and optimum treatment

1550-7289/10/$ – see front matter © 2010 American Society for Metabolic and Bariatric Surgery. All rights reserved. doi:10.1016/j.soard.2009.09.010

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of the patient during the perioperative period. An awareness of the metabolic risk of the patient might allow surgeons and metabolic teams to better understand their patient population and translate into a decrease in surgical complications. Methods The present study included all surgical patients from a private bariatric practice, Scottsdale Bariatric Center, who had undergone Roux-en-Y gastric bypass (RYGB) or laparoscopic adjustable gastric banding (LAGB) for morbid obesity performed by a single surgeon from November 2001 to November 2008. The MAS (Table 1) was devised as a pragmatic communication and management tool for identifying a patient’s metabolic and psychological risk. A retrospective analysis of patients who had undergone surgery before August 2006 was completed. The specific risk factors for complications were developed into a scale. A score was prospectively assigned during the initial visit of each patient beginning in August 2006. As noted in Table 1, preoperative testing could upgrade the patient’s score, and final acuity was assigned during the preoperative visit by the surgeon. If a patient met the criteria for a greater category in any 1 of the measures, they were placed into that category. Two modifiers were used: male gender increased the acuity by 1 level, starting at a MAS of 2, and previous upper abdominal scars increased the acuity by 1 level for patients undergoing RYGB. The preoperative psychological test results and interviews at the initial visit determined the psychological

groups. The psychological grouping played an important role in selecting patients who might not be able to comply with a course of therapy or who might not be ideal candidates for more participatory forms of metabolic surgical therapy and perioperative management. The MAS was presented to the metabolic/bariatric care team before implementation through group and individual teaching sessions. The use of the MAS was imbedded in our programmatic structure and electronic medical record and processing and was used at every level of care. The Scottsdale Healthcare institutional review board approved the database and Health Insurance Portability and Accountability Act consent forms, and all patients completed the form. The data collected included demographic variables, preoperative health indicators, psychological factors, intraoperative conditions, and postoperative outcomes. All data analyses were performed using the Statistical Package for Social Sciences, version 16.0 (SPSS, Chicago, IL) [3], and Stata, version 10 (StataCorp, College Station, TX) [4]. The present study compared the 90-day complication rates of patients who had undergone surgery before implementation of the MAS with those of patients who had undergone surgery after the MAS was applied. RYGB was performed laparoscopically using a circular 21-mm stapler and the pull down technique for the gastrojejunal anastamosis [5,6]. The Roux limb was brought into the upper abdomen using a retrocolic and retrogastric approach. The Roux limb was 100 cm, as measured from the jejunojejunostomy, which was created with a stapled technique [7]. The mesocolic defect was closed with absorbable suture for the first year and with permanent suture thereafter. The

Table 1 Metabolic acuity score Variable

Acuity 1

Acuity 2

Acuity 3

Acuity 4

Age (yr) BMI (kg/m2) Weight (lb) History of DVT/PE

⬍60 ⬍50 ⬍350 No

⬍60 51–54 351–424 No

60–64 55–69 425–599 Personal history or 4 of 8 RFs

OSA (cm H2O)

CPAP ⬍10

CPAP ⱖ10–14

CPAP ⱖ10 plus asthma

T2DM

HbA1c ⱕ7

HbA1c ⬎7

Hypertension Immobile

Pre-T2DM or taking metformin One medication No

⬎65 ⬎70 ⬎600 Currently taking anticoagulation therapy (other than aspirin) CPAP ⬎15 or BIPAP with or without asthma Insulin-dependent T2DM

Yes No

Yes No

History of CAD (stent or CABG) Psychological classification

No 1,2

No 1,2,3A

No 3B

Yes Wheelchair/walker/significant orthopedic difficulties Yes 3B

BMI ⫽ body mass index; DVT/PE ⫽ deep vein thrombosis/pulmonary embolism; RF ⫽ risk factor; OSA ⫽ obstructive sleep apnea; CPAP ⫽ continuous positive airway pressure; BIPAP ⫽ bilevel positive airway pressure; T2DM ⫽ type 2 diabetes mellitus; HbA1c ⫽ hemoglobin A1c; CAD ⫽ coronary artery disease; CABG ⫽ coronary artery bypass graft; MAS ⫽ metabolic acuity score. MAS tentatively assigned at patient’s initial surgical consultation; from preoperative workup findings, surgeon assigns final acuity score at preoperative visit. Male gender: upgrade patient 1 level starting at acuity 2 for RYGB or sleeve gastrectomy; abdominal scar: upgrade patient 1 level for right upper quadrant and upper mid-line scar for either RYGB or LAGB, no upgrade for LAGB for scars below umbilicus.

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269

Table 2 Preoperative demographic and clinical characteristics stratified by procedure type Characteristic

Total (n ⫽ 2416)

RYGB (n ⫽ 1821)

LAGB (n ⫽ 595)

Before MAS Demographic Mean age at surgery (yr) P value Male gender P value Ethnicity White Hispanic Black Native American Other P value Preoperative Mean BMI (kg/m2) P value Mean weight (lb) P value Mean QOL P value Mean HbA1c P value History of DVT/PE P value OSA P value T2DM P value Hypertension P value History of CAD P value Dyslipidemia P value Psych 1 P value Psych 2 P value Psych 3A P value Psych 3B P value Abdominal scar P value

45.4 ⫾ 11.0

After MAS

44.8 ⫾ 10.7

46.5 ⫾ 10.9

Before MAS 43.7 ⫾ 11.3

.002* 549 (30.1)

253 (20.7)

138 (23.1)

1071 (87.5) 95 (7.8) 43 (3.5) 10 (.8) 5 (.4)

35 (29.2)

298.7 ⫾ 64.6

49.5 ⫾ 8.6

495 (83.1) 60 (10.1) 23 (3.9) 12 (2) 6 (1.0)

310.1 ⫾ 65.7

⬍.0001*

114 (95) 5 (4.2) 0 (0) 1 (.8) 0 (0)

42.0 ⫾ 18.1

47.4 ⫾ 7.7

44.3 ⫾ 7.2

6.1 ⫾ 1.3

299.1 ⫾ 61.7

277.5 ⫾ 59.8

64 (2.6)

25 (2)

50.9 ⫾ 20.6

6.9 ⫾ 1.3 24 (4)

601 (49.1)

5.8 ⫾ .7

20 (16.7)

370 (62)

107 (8.7)

52 (43.3)

56 (9.4)

611 (49.9)

6 (5)

325 (54.4)

448 (36.7)

59 (49.2)

157 (26.4)

498 (40.8)

53 (44.2)

311 (52.4)

212 (17.4)

40 (33.3)

98 (16.5)

62 (5.1)

21 (17.5)

28 (4.7)

346 (28.3)

6 (5)

15 (3.2) ⬍.0001†

171 (28.6) NS†

63 (13.4) ⬍.0001†

⬍.0001† 650 (26.9)

261 (55.7) ⬍.0001†

⬍.0001† 111 (4.6)

130 (27.7) ⬍.0001†

⬍.0001† 394 (16.4)

263 (55.4) NS†

⬍.0001† 1110 (46.2)

39 (8.2) NS†

NS† 788 (32.8)

299 (48.2) NS†

NS† 1258 (52.1)

99 (20.8) NS†

⬍.0001† 208 (8.6)

181 (38.1) NS†

214 (35.8)

642 (52.5)

13 (2.7)

37 (30.8)

⬍.0001† 1293 (53.5)

6.6 ⫾ 1.3

NS† 335 (56.1)

312 (25.5)

⬍.0001*

2 (1.7)

.005† 645 (26.7)

51.1 ⫾ 18.3 NS*

⬍.0001† 1154 (47.8)

274.3 ⫾ 58.3 NS*

42.4 ⫾ 17.8 ⬍.0001*

43.3 ⫾ 7.2 NS*

NS* 6.2 ⫾ 1.3

396 (83.4) 46 (9.7) 22 (4.6) 8 (1.7) 3 (.6) .02†

.001* 45.5 ⫾ 18.6

123 (25.9) NS†

.03† 47.5 ⫾ 8.4

45.8 ⫾ 11.9 NS*

NS† 2076 (86) 206 (8.5) 88 (3.6) 31 (1.3) 14 (.6)

After MAS

24 (20)

109 (22.9) NS†

RYGB ⫽ Roux-en-Y gastric bypass; LAGB ⫽ laparoscopic adjustable gastric band; NS ⫽ not statistically significant; QOL ⫽ quality of life; Pysch 1, 2, 3A, 3B ⫽ preoperative psychological classification group; other abbreviations as in Table 1. Data presented as mean ⫾ standard deviation or numbers of patients, with percentages in parentheses. * Independent sample t test or Mann-Whitney U test. † Pearson’s chi-square analysis or Fisher’s exact test.

jejunojejunostomy was closed with permanent suture beginning in April 2007. The LAGB was placed through a pars flaccida approach, using 1–3 permanent sutures to secure the fundus to the pouch. Univariate analyses were executed using Pearson’s chisquare analyses for categorical data and Student’s t tests for interval variables to evaluate statistically significant associations at P ⫽ .05 among the demographic, co-morbidity,

and postoperative outcomes between the use and nonuse of the MAS. Linear mixed models for logistic regression analysis of the binary data of complications were conducted with and without adjustments for baseline covariates (i.e., age, gender, preoperative BMI, and interval to complications) [8]. An event was defined as the occurrence of the particular complication being analyzed. These analyses produced odds ratios that gave us the risk of a complication

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occurring in the pre-MAS group versus the post-MAS group, adjusted for covariates. These analyses allowed us to specify the strength of the association and predictive properties of the MAS by modeling the relationship between complications postoperatively and the implementation of the MAS.

Results From November 2001 to November 2008, 2416 patients underwent bariatric surgery (1821 RYGB of which 97.1% were laparoscopic, and 595 adjustable gastric band procedures of which 99.8% were laparoscopic). The preoperative demographic and clinical characteristics are listed in Table 2. The population before the implementation of the MAS was not as ill as the population after the implementation of the MAS, although the BMI was slightly lower in the post-MAS group, with a weight difference of approximately 10 lb. When conducting the univariate analyses of the postoperative complication rates before and after the MAS was implemented, a significant reduction was found in the rate of postoperative internal hernias, obstructions, intra-abdominal abscesses, pneumonia, leaks, infections, readmissions, and the median length of stay (LOS) for the RYGB group after the MAS was implemented. Readmissions were reduced from 8.5% (n ⫽ 131) to 1.7% (n ⫽ 11; P ⬍.0001). In the LAGB group, band slips, the mean operating room time, and the mean LOS was significantly reduced in the postMAS group compared with the pre-MAS group (Table 3). A linear mixed model for logistic regression was used to describe the likelihood of complications developing in the pre-MAS group compared with the post-MAS group. This type of analysis allows the model to be adjusted for the fixed and random effects of baseline covariates such as age, gender, preoperative BMI, time to the event, and implementation of the MAS. These analyses provided odds ratios, which permitted an extrapolation of the odds of a complication event occurring in one group compared with the odds of that event occurring in another. In the present study, it was a comparison of the patients in the post-MAS group with those in the pre-MAS group. The patients in the RYGB post-MAS group were .30 time less likely to develop an internal hernia compared with the pre-MAS group (P ⫽ .004), .24 time less likely to experience a postoperative infection (P ⫽ .05), .10 time less likely to develop postoperative deep vein thrombosis (P ⫽ .03), .15 time less likely to require readmission (P ⬍.0001), and .13 time less likely to require reoperation (P ⫽ .001). Overall, the use of the MAS resulted in the reduction of complication rates after adjusting for the fixed and random effects of covariates (Table 4).

Table 3 Percentage of complications stratified by metabolic acuity score use Complication

Before MAS

RYGB GI bleeding 15 (1.2) Internal hernia 49 (4) Obstruction 37 (3) Intra-abdominal abscess 22 (1.8) Pneumonia 14 (1.1) Leak 11 (.9) Stricture 87 (7.1) Infection 43 (3.5) Postoperative PE 8 (.7) Postoperative DVT 10 (.8) Readmission 131 (8.5) Reoperation 32 (2.1) Mortality ⬍30 d 1 (.05) Mortality ⬍90 d 4 (.22) Median OR time (min) 86.0 ⫾ 30.5 Mean OR time (min) 93.2 ⫾ 30.5 Median LOS (d) 2.0 ⫾ 2.0 Mean LOS (d) 2.8 ⫾ 2.0 Total patients (n) 1224 LAGB Infection 1 (.8) Band slippage 8 (6.7) Readmission 1 (.8) Reoperation 0 (0) Mortality ⬍30 d 0 (0) Mortality ⬍90 d 0 (0) Mean OR time (min) 51.1 ⫾ 19.7 Mean LOS (d) 1.3 ⫾ .9 Total patients (n) 120

After MAS

P value

3 (.5) 7 (1.2) 7 (1.2) 0 (0) 0 (0) 0 (0) 42 (7) 4 (.7) 2 (.3) 1 (.2) 11 (1.7) 6 (.9) 0 (0) 0 (0) 85.0 ⫾ 30.9 93.0 ⫾ 30.9 2.0 ⫾ 3.5 2.8 ⫾ 3.5 597

.14*† .001*† .016*† ⬍.0001*† .007*† .02*† .96* ⬍.0001*† .51* .12* ⬍.0001*† .06* NS* NS* NS‡

5 (1.1) 3 (.6) 4 (.8) 2 (.4) 0 (0) 0 (0) 46.9 ⫾ 17.9 .8 ⫾ .7 475

.83* ⬍.0001*† .99* .48* NC NC .01†‡ ⬍.0001†‡

.008†‡

GI ⫽ gastrointestinal; OR ⫽ operating room; LOS ⫽ length of stay; NC ⫽ not able to calculate measures of association; other abbreviations as in Tables 1 and 2. Data presented as mean ⫾ standard deviation, median ⫾ standard deviation, or numbers of patients, with percentages in parentheses. * Pearson’s chi-square analysis or Fisher’s exact test. † Statistically significant. ‡ Independent sample t test or Mann-Whitney U test.

Discussion The present study is the first to validate the use of the MAS to improve the safe treatment of metabolic surgical patients. The MAS identifies patients by the burden of their metabolic disease, allowing the surgeon to minimize these factors in the perioperative period and to measure the success of the surgical intervention more precisely for different patient populations. The preoperative clinical characteristics were significantly different before and after the MAS was implemented, with increased metabolic disease in the patient group after MAS implementation. The shift in demographics reflected recently published data from the Agency for Healthcare Research and Quality that the operative population is more ill than the population reported previously. Using the MAS decreased the complications to rates lower than those reported by the Agency for Healthcare Research and Quality [9], American Society for Metabolic and Bari-

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Table 4 Linear mixed model for logistic regression analysis results for complications and use of metabolic acuity score Complication

Odds of complication occurring after MAS relative to before MAS Adjusted* OR (95% CI)

RYGB GI bleeding

P value

.23 (.02–2.42)

.22

Internal hernia

.30 (.13–.68)

.004†

Obstruction

.43 (.15–1.20)

.11

Stricture

.73 (.41–1.32)

.30

Infection

.24 (.06–1.04)

.05†

Postoperative PE

.19 (.02–1.46)

.11

Postoperative DVT

.10 (.01–.80)

.03†

Readmission

.15 (.07–.31)

⬍.0001†

Reoperation

.13 (.04–.42)

.001†

.58 (.06–5.50)

.64

Band slippage

.005 (.0004–4.81)

.13

Readmission

1.26 (.03–52.3)

.90

LAGB Infection

Covariate

Adjusted* OR of covariate (95% CI)

P value

Time to complication Preoperative BMI Age at surgery Male gender Time to complication Preoperative BMI Age at surgery Male gender Time to complication Preoperative BMI Age at surgery Male gender Time to complication Preoperative BMI Age at surgery Male gender Time to complication Preoperative BMI Age at surgery Male gender Time to complication Preoperative BMI Age at surgery Male gender Time to complication Preoperative BMI Age at surgery Male gender Time to complication Preoperative BMI Age at surgery Male gender Time to complication Preoperative BMI Age at surgery Male gender

.99 (.99–1.00) 1.02 (.96–1.07) 1.06 (1.01–1.11) 12.70 (4.0–40.5) 1.00 (1.00–1.00) .99 (.96–1.03) 1.00 (.98–1.02) .85 (.42–1.73) 1.00 (1.00–1.00) .96 (.92–1.00) .98 (.95–1.01) .74 (.30–1.80) 1.00 (1.00–1.00) 1.00 (.97–1.01) .98 (.96–.99) .64 (.39–1.06) 1.00 (1.00–1.00) 1.06 (1.02–1.09) 1.01 (.98–1.04) .73 (.34–1.55) .98 (.97–.99) .99 (.91–1.08) 1.04 (.99–1.11) .88 (.20–3.86) .99 (.98–1.00) 1.03 (.96–1.10) 1.06 (1.00–1.12) 2.42 (.67–8.80) .99 (.99–.99) 1.03 (1.01–1.06) 1.01 (.99–1.03) .97 (.58–1.63) .90 (.86–.94) 1.06 (1.00–1.12) 1.02 (.98–1.07) .91 (.28–2.94)

.14 .57 .03† ⬍.0001† .36 .65 .94 .66 .05† .06 .11 .50 ⬍.0001† .68 .004† .09 .14 .001† .47 .41 .001† .86 .14 .86 .001† .48 .05† .18 ⬍.0001† .015† .18 .92 ⬍.0001† .06 .29 .88

Time to complication Preoperative BMI Age at surgery Male gender Time to complication Preoperative BMI Age at surgery Male gender Time to complication Preoperative BMI Age at surgery Male gender

.99 (.99–1.00) .97 (.86–1.10) 1.01 (.94–1.08) 5.29 (.89–31.30) 1.00 (1.00–1.00) .86 (.74–.99) .95 (.89–1.02) .28 (.03–2.56) .85 (.73–.99) .97 (.76–1.24) 1.01 (.89–1.15) 4.97 (.08–300.6)

.09 .65 .83 .07 .55 .04† .14 .26 .04† .83 .85 .44

GI ⫽ gastrointestinal; other abbreviations as in Tables 1 and 2. * Adjusted for baseline covariates: fixed effects (time to event, preoperative BMI, age, and gender) and random effects (year of surgery and use of MAS). † Statistically significant.

atric Surgery Centers of Excellence [10], or National Surgical Quality Improvement Program [11]. Using the scale to prospectively treat patients improved the safety profile of the bariatric procedures to a level

approaching elective gallbladder surgery. Perhaps the most important aspect of use of the MAS was that it reinforced to the entire care team that surgical patients do not have a specific disease in a vacuum. Obese patients treated for

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general surgical procedures also have a burden of metabolic disease that can affect their outcomes. The MAS focus of our group, along with a commitment to keep and use our data, allowed us to perform continual process improvement and to interpret and incorporate published data into our own practice. Some complications that improved were the result of a change in surgical technique and not attributable strictly to MAS implementation. In the RYGB group, the internal hernia rate decreased dramatically between the pre- and post-MAS groups. In the first year of performing RYGB, the mesocolic defect was closed with absorbable suture, in the second year it was closed with permanent suture, and in the last year, all defects were closed. With LAGB, one major improvement was in band slippage. Clearly, our technique had improved, but we believe band slips result from poor eating behavior and the inability of a patient to adapt their personal eating behavior to the band environment. Using the psychological groups to shift patients to more robust procedures when they were unlikely to be able to bring their behavior in line with the band requirements decreased the number of people eating and vomiting with every meal, and thus, we believe, decreased the slippage rate. Other complications were related to an improvement in technology rather than technique. The band slippage rate is less with the material for all devices available currently; the improvement in stapler technology over time we believe also contributed to a decrease in leakage. Some complications might a resulted from the nature of the specific technique used. Stricture was reported in the same proportion of patients before and after MAS, indicating that a finite risk level might be present that cannot be improved without changing the technique [12]. The most convincing finding that implementing the MAS, in and of itself, improved the outcomes came from the readmission, 30-day reoperation, deep vein thrombosis, and infection rate and overall LOS [13,14]. The use of the MAS resulted in a median LOS of 2 days for RYGB and a readmission rate of 1.7%. For the LAGB group, the LOS was .8 day and the readmission rate was .8%. In the current environment of healthcare reform and financial constraints, a critical eye has been turned to the return of investment from medical and surgical therapies. A return of investment is the difference between the cost and the benefit of surgery. The cost of complications in bariatric surgery was recently cited by the Agency for Healthcare Research and Quality [15] as having decreased to $69,960 for those patients readmitted with complications at a rate of 7%. The LOS was 3.7 days. The cost savings of reducing the LOS and readmission rate is critical to the continued provision of secondary care in the United States. The implementation and use of the MAS can both deliver better quality care to patients and allow us to reduce the cost of that care. In an effort to eliminate variability in the data, we selected a single surgeon’s experience with the laparoscopic

technique in a Center of Excellence environment. We have also calculated similar results for our overall program, which includes four additional surgeons. Detailed data of the outcomes in the four MAS groups will be forthcoming. In any risk score, the subjective aspect of the score is its weakness, and ours includes psychological factors that might be less objective. We have attempted to control for this by having one examiner do all the testing and interviews and assigning the psychological group. The longitudinal nature of the data and the natural improvement with time of the surgical technique have been reasonably validated by the type of model used; however, multicenter validation such as could be implemented and followed in the Bariatric Outcomes Longitudinal Database [BOLD] or bariatric National Surgical Quality Improvement Program is necessary. However, owing to the integral nature of MAS in our program, a randomized prospective study would not be possible at our center. Conclusion Implementation of the MAS could decrease the risk of complications of metabolic surgery and allow surgeons to improve their individual outcomes, especially regarding the LOS and the reoperation, infection, deep vein thrombosis, and readmission rates. Disclosures R. Blackstone, M.D., F.A.C.S., is the principal investigator for a multicenter trial conducted with Enteromedics, the Associate Primary Investigator for a National Institutes of Health/National Institute of Arthritis, Diabetes, Digestive and Kidney Diseases prospective trial on band/bypass and sleeve, and a consultant to Ethicon Endosurgery, Covidien, and Allergen. References [1] Belle SH, Chapman W, Courcoulas AP, et al. Relationship of body mass index with demographic and clinical characteristics in the Longitudinal Assessment of Bariatric Surgery (LABS). Surg Obes Relat Dis 2008;4:474 – 80. [2] DeMaria EJ, Murr M, Byrne TK, et al. Validation of the obesity surgery mortality risk score in a multicenter study proves it stratifies mortality risk in patients undergoing gastric bypass for morbid obesity. Ann Surg 2007;246:578 – 84. [3] Statistical Package for Social Sciences for Windows, release 16.0.1. Chicago: SPSS; 2007. [4] Stata statistical software, release 10. StataCorp: College Station, TX; 2007. [5] Wittgrove AC, Clark GW, Schubert KR. Laparoscopic gastric bypass, Roux-en-Y: technique and results in 75 patients with 3–30 months follow-up. Obes Surg 1996;6:500 – 4. [6] Blackstone R. Roux-en-Y gastric bypass. In: Nguyen NT, DeMaria EJ, Ikramuddin S, Hutter MM, editors. The SAGES manual: a practical guide to bariatric surgery. New York: Springer, 2008. p. 87– 100.

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