Self-reported remission of obstructive sleep apnea following bariatric surgery: cohort study.

BACKGROUND: Evidence on remission of obstructive sleep apnea (OSA) after bariatric surgery and its relation to weight loss is conflicting. We sought to identify factors associated with successful self-reported OSA remission in a large cohort of bariatric surgery patients. METHODS: We analyzed data from the statewide, prospective clinical registry of the Michigan Bariatric Surgery Collaborative and identified 3,550 patients with OSA who underwent a primary bariatric procedure between June 2006 and October 2011 and had at least 1 year of follow-up data. We used multivariate logistic regression to identify preoperative factors associated with successful self-reported OSA remission, defined as discontinuation of continuous positive airway pressure or bilevel positive airway pressure at 1 year. Our regression model also included procedure type and weight loss at 1 year, divided into equal quintiles, as covariates. RESULTS: The overall 1-year self-reported OSA remission rate was 60%. Significant predictors of remission included age category (per 10 yr) (OR .73, CI .69-.78), body mass index category (per 10 units) (OR .57, CI .54-.62), male gender (OR .58, CI .52-.69), hypertension (OR .83, CI .74-.99), depression (OR .78, CI .69-.88), pulmonary disease (OR .88, CI .78-.98), and baseline Health and Activities Limitations Index score (OR 1.70, CI 1.32-2.23). Relative to gastric banding, the adjusted odds of OSA remission were greater with gastric bypass (OR 2.38, CI 1.89-3.08), sleeve gastrectomy (OR 2.01, CI 1.44-2.55), and duodenal switch (OR 2.57, CI 1.02-7.26). The odds ratio of OSA remission increased stepwise through quintiles of 1-year weight loss. Relative to the lowest quintile, the odds ratios of remission in the 2(nd) through 5(th) quintiles were 1.44 (CI 1.11-1.84), 2.03 (CI 1.48-2.57), 2.47 (1.85-3.40), and 3.53 (CI 2.56-4.85). CONCLUSIONS: Weight loss is an important predictor of self-reported OSA remission after bariatric surgery. However, independent of weight loss, there remain significant differences in the likelihood of remission between gastric banding and other bariatric procedures. This suggests that there may be metabolic, weight-independent effects of procedure type on self-reported OSA remission.

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.

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.

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.

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.

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. BACKGROUND: Despite 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.

Preoperative placement of inferior vena cava filters and outcomes after gastric bypass surgery.

OBJECTIVE: To assess relationships between inferior vena cava (IVC) filter placement and complications within 30 days of gastric bypass surgery. SUMMARY OF BACKGROUND DATA: IVC filters are increasingly being used as prophylaxis against postoperative pulmonary embolism in patients undergoing bariatric surgery, despite a lack of evidence of effectiveness. METHODS: On the basis of data from a prospective clinical registry involving 20 Michigan hospitals, we identified 6376 patients undergoing gastric bypass surgery between 2006 and 2008. We then assessed relationships between IVC filter placement and complications within 30 days of surgery. We used propensity scores and fixed effects logistic regression to control for potential selection bias. RESULTS: A total of 542 gastric bypass patients (8.5%) underwent preoperative IVC filter placement, most of whom (65%) had no history of venous thromboembolism. The use of IVC filters for gastric bypass patients varied widely across hospitals (range, 0%-34%). IVC filter patients did not have reduced rates of postoperative venous thromboembolism (adjusted odds ratio [OR], = 1.28; 95% confidence interval [CI], 0.51-3.21), serious complications (adjusted OR, = 1.40; 95% CI, 0.91-2.16), or death/permanent disability (adjusted OR, = 2.49; 95% CI, 0.99-6.26). More than half (57%) of the IVC filter patients in the latter group had a fatal pulmonary embolism or complications directly related to the IVC filter itself, including filter migration or thrombosis of the vena cava. In subgroup analyses, we were unable to identify any patient group for whom IVC filters were associated with improved outcomes. CONCLUSIONS: Prophylactic IVC filters for gastric bypass surgery do not reduce the risk of pulmonary embolism and may lead to additional complications.

Preoperative weight loss is not a predictor of postoperative weight loss after laparoscopic Roux-en-Y gastric bypass.

BACKGROUND: Identification of preoperative predictors of weight loss after laparoscopic Roux-en-Y gastric bypass (LRYGB) can lead to improved clinical outcomes. The purpose of this study was to determine whether preoperative weight loss was associated with improved percentage of excess weight loss (%EWL) 1 year after LRYGB. METHODS: A retrospective analysis was performed on the data from 295 patients who had undergone LRYGB at our institution from July 2004 to November 2005. Routine preoperative weight loss goals were implemented to facilitate the laparoscopic approach and ensure compliance with an appropriate nutritional and exercise program. Patients with an initial consultation BMI of <50, 50-59, and > or =60 kg/m(2) were given weight loss goals of 5 lb and 5% and 10% of body weight, respectively. RESULTS: The mean age was 45 +/- 10 years, and 89% were women and 70% were white. The mean BMI at the initial consultation was 51 +/- 7 kg/m(2). A significant inverse correlation was found between the preoperative BMI and %EWL at 1 year postoperative (P <.001). When controlling for BMI, no correlation was found between the %EWL and percentage of preoperative weight loss or attainment of the weight loss goals. The weight loss goals were met or surpassed by 79% of patients, and the mean %EWL at 1 year was 66%. Whites had greater %EWL at 1 year postoperatively compared with African Americans (67% versus 61%; P = .002). When controlling for age, gender, race, and consultation BMI, the preoperative weight loss did not predict for the %EWL at 1 year. CONCLUSION: The results of this study have shown that preoperative weight loss does not predict postoperative weight loss 1 year after LRYGB. A lower BMI, younger age, and white race predicted better %EWL.

Effect of gastric bypass surgery on vitamin D nutritional status.

BACKGROUND: We previously reported a 60% prevalence of vitamin D (VitD) depletion, defined as a 25-hydroxyvitamin D (25-OHD) level of < or =20 ng/mL, in morbidly obese patients preoperatively. We now report the effect of gastric bypass (GB) on the VitD nutritional status in these patients. METHODS: We prospectively studied 108 morbidly obese patients who had undergone GB. Routine postoperative supplementation consisted of 800 IU VitD and 1500 mg calcium daily. Serum calcium, parathyroid hormone, and 25-OHD were measured before and 1 year after GB. RESULTS: The mean patient age was 46 +/- 9 years, 93% were women, and 72% were white. Preoperatively and at 1 year postoperatively, the prevalence of VitD depletion and hyperparathyroidism (HPT) and the mean 25-OHD level was 53% and 44%, 47% and 39%, and 20 and 24 ng/mL, respectively. One year after GB, the percentage of excess weight loss was 67% and demonstrated significant correlations both positively with 25-OHD and inversely with parathyroid hormone. At both intervals, blacks had a greater incidence of VitD depletion than did whites, and, at 1 year after GB, HPT was more common in patients with VitD depletion (55% versus 26%, P = .002). CONCLUSION: With customary supplementation, VitD nutrition is improved after GB, but VitD depletion persists in almost one half of patients, and blacks are at a significantly greater risk than whites. HPT did not improve, and those with VitD depletion had a significantly greater rate of HPT. Additional prospective studies are needed to determine how to optimize VitD nutrition and avoid potential long-term skeletal complications after GB.

Prevalence of vitamin D depletion among morbidly obese patients seeking gastric bypass surgery.

BACKGROUND: Abnormalities in calcium and vitamin D metabolism have been reported after bariatric surgery. The purpose of this study was to evaluate vitamin D nutritional status among morbidly obese patients before gastric bypass surgery. METHODS: We prospectively studied 279 morbidly obese patients seeking gastric bypass surgery for vitamin D nutritional status as assessed by serum 25-hydroxyvitamin D level. In addition, serum samples were analyzed for calcium, alkaline phosphatase (AP), intact parathyroid hormone (PTH), and 1,25-dihydroxyvitamin D. RESULTS: Mean patient age was 43 +/- 9 years; 87% of the study patients were women, and 72% were white. Serum calcium and AP levels were normal in 88% and 89% of the patients, respectively. Vitamin D depletion, defined as serum 25-hydroxyvitamin D level