Wayne J. English

Hospital Complication Rates With Bariatric Surgery in Michigan

CONTEXT Despite the growing popularity of bariatric surgery, there remain concerns about perioperative safety and variation in outcomes across hospitals. OBJECTIVE To assess complication rates of different bariatric procedures and variability in rates of serious complications across hospitals and according to procedure volume and center of excellence (COE) status. DESIGN, SETTING, AND PATIENTS Involving 25 hospitals and 62 surgeons statewide, the Michigan Bariatric Surgery Collaborative (MBSC) administers an externally audited, prospective clinical registry. We evaluated short-term morbidity in 15,275 Michigan patients undergoing 1 of 3 common bariatric procedures between 2006 and 2009. We used multilevel regression models to assess variation in risk-adjusted complication rates across hospitals and the effects of procedure volume and COE designation (by the American College of Surgeons or American Society for Metabolic and Bariatric Surgery) status. MAIN OUTCOME MEASURE Complications occurring within 30 days of surgery. RESULTS Overall, 7.3% of patients experienced perioperative complications, most of which were wound problems and other minor complications. Serious complications were most common after gastric bypass (3.6%; 95% confidence interval [CI], 3.2%-4.0%), followed by sleeve gastrectomy (2.2%; 95% CI, 1.2%-3.2%), and laparoscopic adjustable gastric band (0.9%; 95% CI, 0.6%-1.1%) procedures (P < .001). Mortality occurred in 0.04% (95% CI, 0.001%-0.13%) of laparoscopic adjustable gastric band, 0 sleeve gastrectomy, and 0.14% (95% CI, 0.08%-0.25%) of the gastric bypass patients. After adjustment for patient characteristics and procedure mix, rates of serious complications varied from 1.6% (95% CI, 1.3-2.0) to 3.5% (95% CI, 2.4-5.0) (risk difference, 1.9; 95% CI, 0.08-3.7) across hospitals. Average annual procedure volume was inversely associated with rates of serious complications at both the hospital level (< 150 cases, 4.1%; 95% CI, 3.0%-5.1%; 150-299 cases, 2.7%; 95% CI, 2.2-3.2; and > or = 300 cases, 2.3%; 95% CI, 2.0%-2.6%; P = .003) and surgeon level (< 100 cases, 3.8%; 95% CI, 3.2%-4.5%; 100-249 cases, 2.4%; 95% CI, 2.1%-2.8%; > or = 250 cases, 1.9%; 95% CI, 1.4%-2.3%; P = .001). Adjusted rates of serious complications were similar in COE and non-COE hospitals (COE, 2.7%; 95% CI, 2.5%-3.1%; non-COE, 2.0%; 95% CI, 1.5%-2.4%; P = .41). CONCLUSIONS The frequency of serious complications among patients undergoing bariatric surgery in Michigan was relatively low. Rates of serious complications are inversely associated with hospital and surgeon procedure volume, but unrelated to COE accreditation by professional organizations.

The comparative effectiveness of sleeve gastrectomy, gastric bypass, and adjustable gastric banding procedures for the treatment of morbid obesity.

Objective:To evaluate the comparative effectiveness of sleeve gastrectomy (SG), laparoscopic gastric bypass (RYGB), and laparoscopic adjustable gastric banding (LAGB) procedures. Background:Citing limitations of published studies, payers have been reluctant to provide routine coverage for SG for the treatment of morbid obesity. Methods:Using data from an externally audited, statewide clinical registry, we matched 2949 SG patients with equal numbers of RYGB and LAGB patients on 23 baseline characteristics. Outcomes assessed included complications occurring within 30 days, and weight loss, quality of life, and comorbidity remission at 1, 2, and 3 years after bariatric surgery. Results:Matching resulted in cohorts of SG, RYGB, and LAGB patients that were well balanced on baseline characteristics. Overall complication rates among patients undergoing SG (6.3%) were significantly lower than for RYGB (10.0%, P < 0.0001) but higher than for LAGB (2.4%, P < 0.0001). Serious complication rates were similar for SG (2.4%) and RYGB (2.5%, P = 0.736) but higher than for LAGB (1.0%, P < 0.0001). Excess body weight loss at 1 year was 13% lower for SG (60%) than for RYGB (69%, P < 0.0001), but was 77% higher for SG than for LAGB (34%, P < 0.0001). SG was similarly closer to RYGB than LAGB with regard to remission of obesity-related comorbidities. Conclusions:With better weight loss than LAGB and lower complication rates than RYGB, SG is a reasonable choice for the treatment of morbid obesity and should be covered by both public and private payers.

Predicting risk for serious complications with bariatric surgery: results from the Michigan Bariatric Surgery Collaborative.

Objectives:To develop a risk prediction model for serious complications after bariatric surgery. BackgroundDespite evidence for improved safety with bariatric surgery, serious complications remain a concern for patients, providers and payers. There is little population-level data on which risk factors can be used to identify patients at high risk for major morbidity. Methods:The Michigan Bariatric Surgery Collaborative is a statewide consortium of hospitals and surgeons, which maintains an externally-audited prospective clinical registry. We analyzed data from 25,469 patients undergoing bariatric surgery between June 2006 and December 2010. Significant risk factors on univariable analysis were entered into a multivariable logistic regression model to identify factors associated with serious complications (life threatening and/or associated with lasting disability) within 30 days of surgery. Bootstrap resampling was performed to obtain bias-corrected confidence intervals and c-statistic. Results:Overall, 644 patients (2.5%) experienced a serious complication. Significant risk factors (P < 0.05) included: prior VTE (odds ratio [OR] 1.90, confidence interval [CI] 1.41–2.54); mobility limitations (OR 1.61, CI 1.23–2.13); coronary artery disease (OR 1.53, CI 1.17–2.02); age over 50 (OR 1.38, CI 1.18–1.61); pulmonary disease (OR 1.37, CI 1.15–1.64); male gender (OR 1.26, CI 1.06–1.50); smoking history (OR 1.20, CI 1.02–1.40); and procedure type (reference lap band): duodenal switch (OR 9.68, CI 6.05–15.49); laparoscopic gastric bypass (OR 3.58, CI 2.79–4.64); open gastric bypass (OR 3.51, CI 2.38–5.22); sleeve gastrectomy (OR 2.46, CI 1.73–3.50). The c-statistic was 0.68 (bias-corrected to 0.66) and the model was well-calibrated across deciles of predicted risk. Conclusions:We have developed and validated a population-based risk scoring system for serious complications after bariatric surgery. We expect that this scoring system will improve the process of informed consent, facilitate the selection of procedures for high-risk patients, and allow for better risk stratification across studies of bariatric surgery.

Systematic review on reoperative bariatric surgery: American Society for Metabolic and Bariatric Surgery Revision Task Force.

BACKGROUND Reoperative bariatric surgery has become a common practice in many bariatric surgery programs. There is currently little evidence-based guidance regarding specific indications and outcomes for reoperative bariatric surgery. A task force was convened to review the current evidence regarding reoperative bariatric surgery. The aim of the review was to identify procedure-specific indications and outcomes for reoperative procedures. METHODS Literature search was conducted to identify studies reporting indications for and outcomes after reoperative bariatric surgery. Specifically, operations to treat complications, failed weight loss, and weight regain were evaluated. Abstract and manuscript reviews were completed by the task force members to identify, grade, and categorize relevant studies. RESULTS A total of 819 articles were identified in the initial search. After review for inclusion criteria and data quality, 175 articles were included in the systematic review and analysis. The majority of published studies are single center retrospective reviews. The evidence supporting reoperative surgery for acute and chronic complications is described. The evidence regarding reoperative surgery for failed weight loss and weight regain generally demonstrates improved weight loss and co-morbidity reduction after reintervention. Procedure-specific outcomes are described. Complication rates are generally reported to be higher after reoperative surgery compared to primary surgery. CONCLUSION The indications and outcomes for reoperative bariatric surgery are procedure-specific but the current evidence does support additional treatment for persistent obesity, co-morbid disease, and complications.

The REDUCE pivotal trial: a prospective, randomized controlled pivotal trial of a dual intragastric balloon for the treatment of obesity

BACKGROUND Saline-filled intragastric balloon devices are reversible endoscopic devices designed to occupy stomach volume and reduce food intake. OBJECTIVE To evaluate the safety and effectiveness of a dual balloon system plus diet and exercise in the treatment of obesity compared to diet and exercise alone. SETTING Academic and community practice, United States. METHODS Participants (n = 326) with body mass index (BMI) 30-40 kg/m(2) were randomized to endoscopic DBS treatment plus diet and exercise (DUO, n = 187) or sham endoscopy plus diet and exercise alone (DIET, n = 139). Co-primary endpoints were a between-group comparison of percent excess weight loss (%EWL) and DUO subject responder rate, both at 24 weeks. Thereafter DUO patients had the DBS retrieved followed by 24 additional weeks of counseling; DIET patients were offered DBS treatment. RESULTS Mean BMI was 35.4. Both primary endpoints were met. DUO weight loss was over twice that of DIET. DUO patients had significantly greater %EWL at 24 weeks (25.1% intent-to-treat (ITT), 27.9% completed cases (CC, n = 167) compared with DIET patients (11.3% ITT, P = .004, 12.3% CC, n = 126). DUO patients significantly exceeded a 35% response rate (49.1% ITT, P<.001, 54.5% CC) for weight loss dichotomized at 25%EWL. Accommodative symptoms abated rapidly with support and medication. Balloon deflation occurred in 6% without migrations. Early retrieval for nonulcer intolerance occurred in 9%. Gastric ulcers were observed; a minor device change led to significantly reduced ulcer size and frequency (10%). CONCLUSION The DBS was significantly more effective than diet and exercise in causing weight loss with a low adverse event profile.

Predicting risk for venous thromboembolism with bariatric surgery: results from the Michigan Bariatric Surgery Collaborative.

Objective:We sought to identify risk factors for venous thromboembolism (VTE) among patients undergoing bariatric surgery in Michigan. Background:VTE remains a major source of morbidity and mortality after bariatric surgery. It is unclear which factors should be used to identify patients at high risk for VTE. Methods:The Michigan Bariatric Surgery Collaborative maintains a prospective clinical registry of bariatric surgery patients. For this study, we identified all patients undergoing primary bariatric surgery between June 2006 and April 2011 and determined rates of VTE. Potential risk factors for VTE were analyzed using a hierarchical logistic regression model, accounting for clustering of patients within hospitals. Significant risk factors were used to develop a risk calculator for development of VTE after bariatric surgery. Results:Among 27,818 patients who underwent bariatric surgery during the study period, 93 patients (0.33%) experienced a VTE complication, including 51 patents with pulmonary embolism. There were 8 associated deaths. Significant risk factors included previous history of VTE (OR 4.15, CI 2.42–7.08); male gender (OR 2.08, CI 1.36–3.19); operative time more than 3 hours (OR 1.86, CI 1.07–3.24); BMI category (per 10 units) (OR 1.37, CI 1.06–1.75); age category (per 10 years) (OR 1.25, CI 1.03–1.51); and procedure type (reference adjustable gastric band): duodenal switch (OR 9.45, CI 2.50–35.97); open gastric bypass (OR 6.48, CI 2.17–19.41); laparoscopic gastric bypass (OR 3.97, CI 1.77–8.91); and sleeve gastrectomy (OR 3.50, CI 1.30–9.34). Nearly 97% of patients had a predicted VTE risk less than 1%. Conclusions:In this population-based study, overall VTE rates were low among patients undergoing bariatric surgery. The use of an empirically based risk calculator will allow for the development of a risk-stratified approach to VTE prophylaxis.

Comparative Effectiveness of Unfractionated and Low-Molecular-Weight Heparin for Prevention of Venous Thromboembolism Following Bariatric Surgery

OBJECTIVE To evaluate the effectiveness and safety of 3 predominant venous thromboembolism (VTE) prophylaxis strategies among patients undergoing bariatric surgery. DESIGN Cohort study. SETTING The Michigan Bariatric Surgery Collaborative, a statewide clinical registry and quality improvement program. PATIENTS Twenty-four thousand seven hundred seventy-seven patients undergoing bariatric surgery between 2007 and 2012. INTERVENTIONS Unfractionated heparin preoperatively and postoperatively (UF/UF), UF heparin preoperatively and low-molecular-weight heparin postoperatively (UF/LMW), and LMW heparin preoperatively and postoperatively (LMW/LMW). MAIN OUTCOME MEASURES Rates of VTE, hemorrhage, and serious hemorrhage (requiring >4 U of blood products or reoperation) occurring within 30 days of surgery. RESULTS Overall, adjusted rates of VTE were significantly lower for the LMW/LMW (0.25%; P < .001) and UF/LMW (0.29%; P = .03) treatment groups compared with the UF/UF group (0.68%). While UF/LMW (0.22%; P = .006) and LMW/LMW (0.21%; P < .001) were similarly effective in patients at low risk of VTE (predicted risk <1%), LMW/LMW (1.46%; P = .10) seemed more effective than UF/LMW (2.36%; P = .90) for high-risk (predicted risk ≥1%) patients. There were no significant differences in rates of hemorrhage or serious hemorrhage among the treatment strategies. CONCLUSION Low-molecular-weight heparin is more effective than UF heparin for the prevention of postoperative VTE among patients undergoing bariatric surgery and does not increase rates of bleeding.

Composite measures for profiling hospitals on bariatric surgery performance

IMPORTANCE The optimal approach for profiling hospital performance with bariatric surgery is unclear. OBJECTIVE To develop a novel composite measure for profiling hospital performance with bariatric surgery. DESIGN, SETTING, AND PARTICIPANTS Using clinical registry data from the Michigan Bariatric Surgery Collaborative, we studied all patients undergoing bariatric surgery from January 1, 2008, through December 31, 2010. For laparoscopic gastric bypass surgery, we used empirical Bayes techniques to create a composite measure by combining several measures, including serious complications, reoperations, and readmissions; hospital and surgeon volume; and outcomes with other related procedures. Hospitals were ranked for 2008 through 2009 and placed in 1 of 3 groups: 3-star (top 20%), 2-star (middle 60%), and 1-star (bottom 20%). We assessed how well these ratings predicted outcomes in the next year (2010) compared with other widely used measures. MAIN OUTCOMES AND MEASURES Risk-adjusted serious complications. RESULTS Composite measures explained a larger proportion of hospital-level variation in serious complication rates with laparoscopic gastric bypass than other measures. For example, the composite measure explained 89% of the variation compared with only 28% for risk-adjusted complication rates alone. Composite measures also appeared better at predicting future performance compared with individual measures. When ranked on the composite measure, 1-star hospitals had 2-fold higher serious complication rates (4.6% vs 2.4%; odds ratio, 2.0; 95% CI, 1.1-3.5) compared with 3-star hospitals. Differences in serious complication rates between 1- and 3-star hospitals were much smaller when hospitals were ranked using serious complications (4.0% vs 2.7%; odds ratio, 1.6; 95% CI, 0.8-2.9) and hospital volume (3.3% vs 3.2%; odds ratio, 0.85; 95% CI, 0.4-1.7). CONCLUSIONS AND RELEVANCE Composite measures are much better at explaining hospital-level variation in serious complications and predicting future performance than other approaches. In this preliminary study, it appears that such composite measures may be better than existing alternatives for profiling hospital performance with bariatric surgery.

Risks and benefits of prophylactic inferior vena cava filters in patients undergoing bariatric surgery

BACKGROUND The United States Food and Drug Administration recently issued a warning about adverse events in patients receiving inferior vena cava (IVC) filters. OBJECTIVE To assess relationships between IVC filter insertion and complications while controlling for differences in baseline patient characteristics and medical venous thromboembolism prophylaxis. DESIGN Propensity-matched cohort study. SETTING The prospective, statewide, clinical registry of the Michigan Bariatric Surgery Collaborative. PATIENTS Bariatric surgery patients (n=35,477) from 32 hospitals during the years 2006 through 2012. INTERVENTION Prophylactic IVC filter insertion. MEASUREMENTS Outcomes included the occurrence of complications (pulmonary embolism, deep vein thrombosis, and overall combined rates of complications by severity) within 30 days of bariatric surgery. RESULTS There were no significant differences in baseline characteristics among the 1,077 patients with IVC filters and in 1,077 matched control patients. Patients receiving IVC filters had higher rates of pulmonary embolism (0.84% vs 0.46%; odds ratio [OR], 2.0; 95% confidence interval [CI], 0.6-6.5; P=0.232), deep vein thrombosis (1.2% vs 0.37%; OR, 3.3; 95% CI, 1.1-10.1; P=0.039), venous thromboembolism (1.9% vs 0.74%; OR, 2.7; 95% CI, 1.1-6.3, P=0.027), serious complications (5.8% vs 3.8%; OR, 1.6; 95% CI, 1.0-2.4; P=0.031), permanently disabling complications (1.2% vs 0.37%; OR, 4.3; 95% CI, 1.2-15.6; P=0.028), and death (0.7% vs 0.09%; OR, 7.0; 95% CI, 0.9-57.3; P=0.068). Of the 7 deaths among patients with IVC filters, 4 were attributable to pulmonary embolism and 2 to IVC thrombosis/occlusion. CONCLUSIONS We have identified no benefits and significant risks to the use of prophylactic IVC filters among bariatric surgery patients and believe that their use should be discouraged.

Variation in utilization of acid-reducing medication at 1 year following bariatric surgery: results from the Michigan Bariatric Surgery Collaborative ☆

BACKGROUND Morbidly obese patients undergoing bariatric surgery have high rates of gastroesophageal reflux and are often treated with acid-reducing medications (ARM) such as proton pump inhibitors or H2-blockers. The objective of this study was to evaluate the effect of bariatric procedures on the utilization of ARM. We analyzed data from the clinical registry of the Michigan Bariatric Surgery Collaborative on 35,477 patients undergoing bariatric surgery between January 2006 and October 2012 who completed both baseline and 1-year follow-up surveys. Procedures included laparoscopic adjustable gastric banding (LAGB, n=2,627), Roux-en-Y gastric bypass (RYGB, n=6,410), sleeve gastrectomy (SG, n=1,567), and biliopancreatic diversion with duodenal switch (BPD/DS, n=162). METHODS Rates of ARM at 1 year by procedure type were compared using logistic regression analysis. Models were adjusted for patient characteristics, baseline co-morbidities, weight loss, and hiatal hernia repair. RESULTS Overall ARM use at baseline was 37.7% and declined to 29.6% at 1 year after bariatric surgery. The proportion of patients starting an ARM at 1 year when they were not using one at baseline by procedure was LAGB (13.9%), RYGB (19.2%), SG (21.6%), and BPD/DS (26.7%). The proportion of patients discontinuing an ARM at 1 year when they were using one at baseline by procedure was LAGB (55.6%), RYGB (56.2%), SG (37.3%), and BPD/DS (42.1%). Compared with LAGB on multivariable analysis, the likelihood of ARM use at 1 year was higher for SG (OR 1.70, 95% CI 1.45-1.99) and BDP/DS (OR 1.53, CI .97-2.40) but not different for RYGB (OR 1.02, CI .90-1.16). CONCLUSION Overall ARM use decreases after bariatric surgery; however, it is not uniform and depends on procedure type. SG is a significant predictor for ARM use at 1 year.