Obesity-associated sleep hypoventilation and increased adverse postoperative bariatric surgery outcomes in a large clinical retrospective cohort.

STUDY OBJECTIVES: Although obesity hypoventilation syndrome (OHS) is associated with increased morbidity and mortality, post-bariatric surgery OHS risk remains unclear due to often nonsystematic OHS assessments. METHODS: We leverage a clinical cohort with nocturnal CO2 monitoring during polysomnography to address the hypothesis that patients with obesity-associated sleep hypoventilation (OaSH; ie, stage II OHS) have increased adverse postoperative bariatric surgery outcomes. We retrospectively analyzed data from patients undergoing pre-bariatric surgery polysomnography at the Cleveland Clinic from 2011-2018. OaSH was defined by body mass index ≥ 30 kg/m2 and either polysomnography-based end-tidal CO2 ≥ 45 mmHg or serum bicarbonate ≥ 27 mEq/L. Outcomes considered were as follows: intensive care unit stay, intubation, tracheostomy, discharge disposition other than home or 30-day readmission individually and as a composite, and all-cause mortality. Two-sample t test or Wilcoxon rank-sum test for continuous variables and chi-square or Fisher's exact test for categorical variables were used for OaSH vs non-OaSH comparisons. All-cause mortality was compared using Kaplan-Meier estimation and Cox proportional hazards models. RESULTS: The analytic sample (n = 1,665) was aged 45.2 ± 12 years, 20.4% were male, had a body mass index of 48.7 ± 9 kg/m2, and 63.6% were White. OaSH prevalence was 68.5%. OaSH patients were older and more likely to be male with a higher BMI, apnea-hypopnea index, and glycated hemoglobin. The composite outcome was higher in OaSH vs non-OaSH patients (18.9% vs 14.3%, P = .021). Although some individual outcomes were respectively higher in OaSH vs non-OaSH patients, differences were not statistically significant: intubation (1.5% vs 1.3%, P = .81) and 30-day readmission (13.8% vs 11.3%, P = .16). Long-term mortality (median follow-up: 22.9 months) was not significantly different between groups, likely due to overall low event rate (hazard ratio = 1.39, 95% confidence interval: 0.56, 3.42). CONCLUSIONS: In this largest sample to date of systematically phenotyped OaSH in a bariatric surgery cohort, we identify increased postoperative morbidity in those with sleep-related hypoventilation in stage II OHS when a composite outcome was considered, but individual contributors of intubation, intensive care unit admission, and hospital length of stay were not increased. Further study is needed to identify whether perioperative treatment of OaSH improves post-bariatric surgery outcomes. CITATION: Chindamporn P, Wang L, Bena J, et al. Obesity-associated sleep hypoventilation and increased adverse postoperative bariatric surgery outcomes in a large clinical retrospective cohort. J Clin Sleep Med. 2022;18(12):2793-2801.

Perioperative management of diabetes in patients undergoing bariatric and metabolic surgery: a narrative review and the Cleveland Clinic practical recommendations.

Bariatric and metabolic surgery is an effective treatment for patients with severe obesity and obesity-related diseases. In patients with type 2 diabetes, it provides marked improvement in glycemic control and even remission of diabetes. In patients with type 1 diabetes, bariatric surgery may offer improvement in insulin sensitivity and other cardiometabolic risk factors, as well as amelioration of the mechanical complications of obesity. Because of these positive outcomes, there are increasing numbers of patients with diabetes who undergo bariatric surgical procedures each year. Prior to surgery, efforts should be made to optimize glycemic control. However, there is no need to delay or withhold bariatric surgery until a specific glycosylated hemoglobin target is reached. Instead, treatment should focus on avoidance of early postoperative hyperglycemia. In general, oral glucose-lowering medications and noninsulin injectables are not favored to control hyperglycemia in the inpatient setting. Hyperglycemia in the hospital is managed with insulin, aiming for perioperative blood glucose concentrations between 80 and 180 mg/dL. Following surgery, substantial changes of the antidiabetic medication regimens are common. Patients should have a clear understanding of the modifications made to their treatment and should be followed closely thereafter. In this review article, we describe practical recommendations for the perioperative management of diabetes in patients with type 2 or type 1 diabetes undergoing bariatric surgery. Specific recommendations are delineated based on the different treatments that are currently available for glycemic control, including oral glucose-lowering medications, noninsulin injectables, and a variety of insulin regimens.

Assessment of empiric body mass index-based thromboprophylactic dosing of enoxaparin after bariatric surgery: evidence for dosage adjustment using anti-factor Xa in high-risk patients.

BACKGROUND: Despite thromboprophylaxis, postoperative deep vein thrombosis and pulmonary embolism occur after bariatric surgery, perhaps because of failure to achieve optimal prophylactic levels in the obese population. OBJECTIVES: The aim of this study was to evaluate the adequacy of prophylactic dosing of enoxaparin in patients with severe obesity by performing an antifactor Xa (AFXa) assay. SETTING: An academic medical center METHODS: In this observational study, all bariatric surgery cases at an academic center between December 2016 and April 2017 who empirically received prophylactic enoxaparin (adjusted by body mass index [BMI] threshold of 50 kg/m2) were studied. The AFXa was measured 3-5 hours after the second dose of enoxaparin. RESULTS: A total of 105 patients were included; 85% were female with a median age of 47 years. In total, 16 patients (15.2%) had AFXa levels outside the prophylactic range: 4 (3.8%) cases were in the subprophylactic and 12 (11.4%) cases were in the supraprophylactic range. Seventy patients had a BMI <50 kg/m2 and empirically received enoxaparin 40 mg every 12 hours; AFXa was subprophylactic in 4 (5.7%) and supraprophylactic in 6 (8.6%) of these patients. Of the 35 patients with a BMI ≥50 who empirically received enoxaparin 60 mg q12h, no AFXa was subprophylactic and 6 (17.1%) were supraprophylactic. Five patients (4.8%) had major bleeding complications. One patient developed pulmonary embolism on postoperative day 35. CONCLUSION: BMI-based thromboprophylactic dosing of enoxaparin after bariatric surgery could be suboptimal in 15% of patients with obesity. Overdosing of prophylactic enoxaparin can occur more commonly than underdosing. AFXa testing can be a practical way to measure adequacy of pharmacologic thromboprophylaxis, especially in patients who are at higher risk for venous thromboembolism or bleeding.

Elucidating Predictors of Obesity Hypoventilation Syndrome in a Large Bariatric Surgery Cohort.

Rationale: Although understanding predictors of obesity hypoventilation syndrome (OHS), a condition associated with increased morbidity and mortality, is of key importance for risk prediction, existing characterization is limited.Objectives: We hypothesize that OHS patients referred for bariatric surgery have more severe obstructive sleep apnea and metabolic derangements compared with their eucapnic counterparts.Methods: A total of 1,718 patients undergoing polysomnography with end-tidal CO2 monitoring prior to bariatric surgery at Cleveland Clinic from September 2011 to September 2018 were included. OHS was defined by body mass index (BMI) ≥ 30 kg/m2 and either polysomnography-based end-tidal CO2 ≥ 45 mm Hg or serum bicarbonate levels ≥ 27 mEq/L based on the updated European Respiratory Society guidelines. Unadjusted and multivariable logistic regression models (odds ratio; 95% confidence interval) were used to examine OHS predictors consisting of factors in domains of patient characteristics, polysomnography (cardiorespiratory and sleep architecture), laboratory, and metabolic parameters.Results: The analytic sample comprised 1,718 patients with the following characteristics: age of 45.3 ± 12.1 years, 20.7% were male, BMI = 48.6 ± 9 kg/m2, and 63.6% were white individuals. OHS prevalence was 68.4%. Unadjusted analyses revealed a 1.5% increased odds of OHS (1.01; 1.00-1.03) per 1-unit BMI increase, 1.7% (1.02; 1.01-1.02) per 1% increase in sleep time SaO2 < 90%, 12% increase (1.12; 1.03-1.22) per 1-U increase in hemoglobin A1c, and 3.4% increased odds (1.03; 1.02-1.05) per 5-U increase in apnea-hypopnea index. The association of apnea-hypopnea index with OHS persisted after adjustment for age, sex, race, and BMI and its comorbidities (1.02; 1.01-1.04).Conclusions: OHS was highly prevalent in patients referred for bariatric surgery by more than two-thirds. Even after consideration of confounders including obesity, obstructive sleep apnea remained a strong OHS predictor, as were increasing age, male sex, nocturnal hypoxia, and impaired long-term glucose control. These findings can inform OHS risk stratification in bariatric surgery and set the stage for experimental studies to examine sleep-related respiratory and metabolic contributions to hypoventilation.

The Effect of Starting the Protein-Sparing Modified Fast on Weight Change over 5 years.

BACKGROUND: Ketogenic diets have been highlighted as a way to lose weight while experiencing reduced hunger. The protein-sparing modified fast (PSMF) induces ketosis but may be difficult to maintain. OBJECTIVE: To track weight loss for individuals initiating PSMF versus all other diets (e.g., balanced, high protein) for up to 5 years. DESIGN: Retrospective cohort study PARTICIPANTS: Adults who discussed the PSMF with a clinician between 2007 and 2014 INTERVENTION: Initiating the PSMF diet versus other diets MEASURES: The main outcome was percent weight change up to 5 years. Demographic and health data were collected using electronic health records. We fit regression models including age, sex, race, insurance, new medication prescriptions, and specialist visit to identify the effect of PSMF diet on percent weight change. We grouped patients by percent weight change at each year (≥ 5% loss, 4% loss to 4% gain, ≥ 5% gain) and used Pearson χ2 tests to compare proportions. RESULTS: Of 1,403 eligible patients, 879 (63%) started the PSMF. The PSMF group was slightly younger (52 vs. 54 years, p < 0.01) and had a higher body mass index (41.9 kg/m2 vs. 40.4 kg/m2, p < 0.001). In the adjusted analysis, the PSMF group averaged 3% more weight loss than the other group over the 5-year follow-up (95% CI - 3.5, - 2.0, p < 0.001). PSMF patients lost more weight initially, but by year 4, there was no difference between diets (1.6% versus 1.3%, PSMF versus other diets, p = 0.12). Patients starting the PSMF were more likely to experience ≥ 5% weight loss at 1 year (55% vs 20%, p < 0.001) and 3 years (33% vs. 23% p < 0.05), but not 5 years (34% vs 29%, p = 0.16, PSMF versus other diets, respectively). CONCLUSIONS: In clinical practice, the PSMF achieves rapid weight loss in the first 6 months, but only a small percentage of patients maintained significant weight loss long term.

Adjustments to warfarin dosing after gastric bypass and sleeve gastrectomy.

BACKGROUND: Warfarin dosing after bariatric surgery may be influenced by alterations in gastrointestinal pH, transit time, absorptive surface area, gut microbiota, food intake, and adipose tissue. OBJECTIVES: The aim of this study was to describe trends in warfarin dosing after Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG). SETTING: Single academic center. METHODS: All patients chronically on warfarin anticoagulation before RYGB or SG were retrospectively identified. Indications for anticoagulation, history of bleeding or thrombotic events, perioperative complications, and warfarin dosing were collected. RESULTS: Fifty-three patients (RYGB n = 31, SG n = 22) on chronic warfarin therapy were identified (56.6% female, mean 54.4 ± 11.7 yr of age). Of this cohort, 34.0% had prior venous thromboembolic events, 43.4% had atrial fibrillation, and 5.7% had mechanical cardiac valves. Preoperatively, the average daily dose of warfarin was similar in the RYGB group (8.3 ± 4.1 mg) and SG group (6.9 ± 2.8 mg). One month after surgery, mean daily dose of warfarin was reduced 24.1% in the RYGB group (P<.001) and 23.2% in the SG group (P = .002). At 12 months postoperatively, the required daily warfarin dose compared with baseline remained statistically different (RYGB: 6.8 ± 3.8 mg; SG: 6.1 ± 2.0 mg). CONCLUSIONS: The warfarin dose is expected to be decreased by approximately 25% from preoperative levels after both RYGB and SG. Lower dose requirement within the first month after bariatric surgery is followed by a trend toward increased warfarin dose requirements, but remain less than baseline. Because dose requirements change constantly over time, frequent postoperative monitoring of the international normalized ratio is recommended.

Efficacy of adjuvant weight loss medication after bariatric surgery.

BACKGROUND: Some patients do not achieve optimal weight loss or regain weight after bariatric surgery. In this study, we aimed to determine the effectiveness of adjuvant weight loss medications after surgery for this group of patients. SETTING: An academic medical center. METHODS: Weight changes of patients who received weight loss medications after bariatric surgery from 2012 to 2015 at a single center were studied. RESULTS: Weight loss medications prescribed for 209 patients were phentermine (n = 156, 74.6%), phentermine/topiramate extended release (n = 25, 12%), lorcaserin (n = 18, 8.6%), and naltrexone slow-release/bupropion slow-release (n = 10, 4.8%). Of patients, 37% lost>5% of their total weight 1 year after pharmacotherapy was prescribed. There were significant differences in weight loss at 1 year in gastric banding versus sleeve gastrectomy patients (4.6% versus .3%, P = .02) and Roux-en-Y gastric bypass versus sleeve gastrectomy patients (2.8% versus .3%, P = .01).There was a significant positive correlation between body mass index at the start of adjuvant pharmacotherapy and total weight loss at 1 year (P = .025). CONCLUSION: Adjuvant weight loss medications halted weight regain in patients who underwent bariatric surgery. More than one third achieved>5% weight loss with the addition of weight loss medication. The observed response was significantly better in gastric bypass and gastric banding patients compared with sleeve gastrectomy patients. Furthermore, adjuvant pharmacotherapy was more effective in patients with higher body mass index. Given the low risk of medications compared with revisional surgery, it can be a reasonable option in the appropriate patients. Further studies are necessary to determine the optimal medication and timing of adjuvant pharmacotherapy after bariatric surgery.

Who Should Get Extended Thromboprophylaxis After Bariatric Surgery?: A Risk Assessment Tool to Guide Indications for Post-discharge Pharmacoprophylaxis.

OBJECTIVE: To determine the risk factors for 30-day postdischarge venous thromboembolism (VTE) after bariatric surgery and to identify potential indications for extended pharmacoprophylaxis. BACKGROUND: VTE is among most common causes of death after bariatric surgery. Most VTEs occur after hospital stay; still a few patients receive extended pharmacoprophylaxis postdischarge. METHODS: From American College of Surgeons-National Surgical Quality Improvement Program, we identified 91,963 patients, who underwent elective primary and revisional bariatric surgery between 2007 and 2012. Regression-based techniques were used to create a risk assessment tool to predict risk of postdischarge VTE. The model was validated using the 2013 American College of Surgeons-National Surgical Quality Improvement Program dataset (N = 20,575). Significant risk factors were used to create a user-friendly online risk calculator. RESULTS: The overall 30-day incidence of postdischarge VTE was 0.29% (N = 269). In those experiencing a postdischarge VTE, mortality increased about 28-fold (2.60% vs 0.09%; P < 0.001). Among 45 examined variables, the final risk-assessment model contained 10 categorical variables including congestive heart failure, paraplegia, reoperation, dyspnea at rest, nongastric band surgery, age ≥60 years, male sex, BMI ≥50 kg/m, postoperative hospital stay ≥3 days, and operative time ≥3 hours. The model demonstrated good calibration (Hosmer-Lemeshow goodness-of-fit test, P = 0.71) and discrimination (c-statistic = 0.74). Nearly 2.5% of patients had a predicted postdischarge VTE risk >1%. CONCLUSIONS: More than 80% of post-bariatric surgery VTE events occurred post-discharge. Congestive heart failure, paraplegia, dyspnea at rest, and reoperation are associated with the highest risk of post-discharge VTE. Routine post-discharge pharmacoprophylaxis can be considered for high-risk patients (ie, VTE risk >0.4%).

Comprehensive Evaluation for Obesity: Beyond Body Mass Index.

Many factors contribute to the diagnosis of obesity in a patient. Anthropometric measurements, such as the waist circumference and percentage of body fat, are used in the newly released obesity algorithm to risk stratify patients. Staging methods, which use the identification of comorbidities and disease burden to assess the severity of obesity, can result in treating a patient sooner than if the traditional body mass index is used. Obesity is a growing concern in the medical field, and providing additional avenues through which to diagnose obesity and address obesity-related health risks can improve prevention efforts and lead to expedited weight management. Obesity is a growing concern in the medical field, and providing additional avenues through which to diagnose obesity and address obesity-related health risks can improve prevention efforts and lead to expedited weight management.

Bariatric and metabolic outcomes in the super-obese elderly.

BACKGROUND: Numerous reports address bariatric outcomes in super-obese or elderly patients, but data addressing this high-risk combination is lacking. OBJECTIVE: The objective of this study was to assess outcomes of bariatric surgery in the super-obese elderly. SETTING: Academic institution, United States. METHODS: All primary bariatric cases performed on patients aged 65 years or older with a body mass index (BMI) ≥ 50 kg/m(2) were retrospectively analyzed. Surgical approaches included laparoscopic Roux-en-Y gastric bypass (LRYGB), laparoscopic sleeve gastrectomy (LSG), and laparoscopic adjustable gastric banding (LAGB). RESULTS: Thirty patients (26 female, 4 male) with a mean age of 67.1 ± 2.7 years and BMI of 55.9 ± 3.9 kg/m(2), who had LRYGB (n = 16), LSG (n = 6), or LAGB (n = 8), were identified. There were no deaths, conversions, or intraoperative complications. Three patients were lost to follow-up after the 3-month visit. The early (<30 d) major morbidity rate was 10.0%. At a median follow-up of 37 (range, 6-95) months, the cohort had a mean BMI of 42.3 ± 6.7 kg/m(2), which corresponded to a mean percent excess weight loss of 44.5% ± 20.5% and mean percent total weight loss of 24.4% ± 12.2%. The most percent excess weight loss was achieved after LRYGB (54.1% ± 19.4%), followed by LSG (48.3% ± 10.2%) and then LAGB (26.2% ± 14.4%). Diabetic medication reduction in number and/or dosage was observed in 40% (6/15) patients, and 33% (5/15) of patients were completely off antidiabetic agents. CONCLUSIONS: Although further research is needed, the present data suggest that successful weight loss and metabolic improvement can be achieved safely in the high-risk population of super-obese elderly.

Obesity in the elderly: more complicated than you think.

The number of obese older adults is on the rise, although we lack a proper definition of obesity in this age group. The ambiguity is primarily related to sarcopenia, the progressive loss of muscle and gain in fat that come with aging. Whether to treat and how to treat obesity in the elderly is controversial because of a paucity of established guidelines, but also because of the obesity paradox-ie, the apparently protective effect of obesity in this age group.

Effects of bariatric surgery on diabetic nephropathy after 5 years of follow-up.

BACKGROUND: Studies have reported that the benefits of bariatric surgery extend beyond durable weight loss and include significant improvement in glycemic control. We hypothesized that improving diabetes control may have positive effects on end-organ complications of this disease, such as diabetic nephropathy (DN). METHODS: We identified all patients with type 2 diabetes mellitus (T2DM) who underwent bariatric surgery at our institution and had completed a 5-year follow-up. Patients' current diabetes status (remission, improvement, or no change) was determined by biochemical analyses and medication review. The presence of DN, preoperatively and postoperatively, was determined by urinary albumin/creatinine ratio (uACR). RESULTS: Fifty-two T2DM patients underwent bariatric surgery and had completed 5-year follow-up, including serial uACR measurements (25% male; age 51.2 ± 10.1 years). Preoperative body mass index (BMI) was 49 ± 8.7 kg/m(2), mean duration of T2DM was 8.6 years (range .3-39), and baseline HbA(1c) was 7.7% ± 1.4%. DN, as indicated by microalbuminuria (30-300 mg/g) or macroalbuminuria (>300 mg/g), was present in 37.6% preoperatively. Of these, DN resolved in 58.3% at a mean follow-up of 66 months (range 60-92 ). Among those with no evidence of DN preoperatively, albuminuria proceeded to develop 5 years later in only 25%. The 5-year remission and improvement rates for T2DM were 44% and 33%, respectively. Mean reductions in fasting glucose and glycosylated hemoglobin (HbA(1c)) were 36.6 mg/dL and 1.2%, respectively. CONCLUSION: Bariatric surgery can induce a significant and sustainable improvement in T2DM and improve or halt the development of microvascular complications such as nephropathy. Considering that diabetes is often a progressive disease, these results are clinically important and warrant further investigation.