The %EBMIL/%EWL Double Booby-Trap. A Comment on Studies that Compare the Effect of Bariatric Surgery Between Heavier and Lighter Patients

Sex dimorphism in the effect and predictors of weight loss after sleeve gastrectomy

Background

No sex-specific guidelines for surgical anti-obesity strategies have been proposed, partially due to the controversy regarding sex-related differences in weight loss after bariatric metabolic surgery.

Objectives

To explore sex dimorphism in the effect and predictors of weight loss after sleeve gastrectomy (SG), thereby providing clinical evidence for the sex-specific surgical treatment strategy.

Methods

In a prospective cohort design, participants scheduled for SG at an affiliated hospital between November 2020 and January 2022 were assessed for eligibility and allocated to the Male or Female group with a 1-year follow-up after surgery. The primary outcome was the sex difference in the weight-loss effect after SG indicated by both percentage of total weight loss (TWL%) and excess weight loss (EWL%). The secondary outcome was the analysis of sex-specific preoperative predictors of weight loss after SG based on univariate and multivariate analyses. Independent predictors were obtained to construct a nomogram model. The discrimination, calibration, and clinical utility of the nomogram were based on receiver operating characteristic curve, concordance index, calibration curve, and decision curve analysis, respectively.

Results

Ninety-five male and 226 female patients were initially included. After propensity score matching by baseline body mass index (BMI), 85 male and 143 female patients achieved comparable TWL% and EWL% for 1 year after SG. For male patients, baseline BMI, area under the curve for insulin during oral glucose tolerance test, and progesterone were independent predictors of weight loss after SG. Baseline BMI, age, thyroid stimulating hormone, and Self-Rating Anxiety Scale score were independent predictors for female patients.

Conclusion

No obvious sex difference is detected in the weight-loss effect after SG. Sex dimorphism exists in the predictors of weight loss after SG. Further research with long-term and a multicenter design is needed to confirm the predictive model.

The nature of expectations of bariatric surgery in patients during the pre- and post-operative period: A unicentric, qualitative study of patient perspectives

Many patients (20%-30%) experience suboptimal weight loss (WL) after bariatric surgery (BS), and unrealistic preoperative WL expectations may be a contributing factor. This study aimed to describe the nature of patients' general expectations of BS during the pre-surgical period, and how patients determined whether their expectations and WL goals (WLGs) were realistic. The extent to which patients' expectations and WLGs were met and/or changed during the post-surgical period was also assessed. Semi-structured interviews were conducted with 15 preoperative patients recruited approximately 6-months before surgery. Focus groups were also conducted with 14 post-operative patients recruited approximately 6-months after surgery. Interviews and focus groups were audio-recorded, transcribed verbatim and analysed using qualitative content analysis. Preoperative patients reported expectations that BS would positively impact physical and psychological health, social relationships, as well as quality of care. Preoperative patients perceived that they and their health care professionals had unrealistically high expectations of WL. Post-operative patients reported being generally satisfied with the outcomes of surgery, even though many did not reach their expected WL. Finally, most post-operative patients reported changing their expectations from pre- to post-surgery. This study provides data that may help inform the development of preoperative interventions focusing on helping patients set realistic expectations for WL and related outcomes, which could better prepare patients for the challenges they will face after surgery.

Reference Values for Weight Loss During 1 Year After Sleeve Gastrectomy: a Multicenter Retrospective Study in Japan

INTRODUCTION

This study aimed to provide reference values for the percentage total weight loss during 1 year after laparoscopic sleeve gastrectomy associated with primary response in Japan.

METHODS

This multicenter retrospective study comprised 248 patients with severe obesity who underwent laparoscopic sleeve gastrectomy at five institutions in Japan. A percentage total weight loss < 20% at 1 year was defined as primary non-response. Parsimonious predictive models were developed based on the results of multiple regression analyses. A receiver operating characteristic curve analysis was used to assess the discriminative performance for primary non-response.

RESULTS

The median age, initial body mass index, and percentage total weight loss at 1 year were 41 years, 41.4 kg/m², and 30.1%, respectively. There were 28 (11.3%) primary non-responders. For discriminating primary non-responders, the areas under the receiver operating characteristic curve of the parsimonious model and actual percentage of total weight loss at 3 months after laparoscopic sleeve gastrectomy were 0.846 and 0.803, respectively. Cutoffs for the predicted percentage total weight loss using the model and actual value of percentage total weight loss at 3 months attaining 80% sensitivity were 30% and 22%, and those attaining 98% specificity were 22% and 15%, respectively.

CONCLUSIONS

Reference values for the percentage total weight loss at 3 months were obtained using the predictive model and actual value of percentage total weight loss at 3 months. Patients at risk for primary non-response can be determined at 3 months with these values, which can help in considering earlier interventions.

Genetic markers of abdominal obesity and weight loss after gastric bypass surgery

Background

Weight loss after bariatric surgery varies widely between individuals, partly due to genetic differences. In addition, genetic determinants of abdominal obesity have been shown to attenuate weight loss after dietary intervention with special attention paid to the rs1358980-T risk allele in the VEGFA locus. Here we aimed to test if updated genetic risk scores (GRSs) for adiposity measures and the rs1358980-T risk allele are linked with weight loss following gastric bypass surgery.

Methods

Five hundred seventy six patients with morbid obesity underwent Roux-en-Y gastric bypass. A GRS for BMI and a GRS for waist-hip-ratio adjusted for BMI (proxy for abdominal obesity), respectively, were constructed. All patients were genotyped for the rs1358980-T risk allele. Associations between the genetic determinants and weight loss after bariatric surgery were evaluated.

Results

The GRS for BMI was not associated with weight loss (β = -2.0 kg/100 risk alleles, 95% CI -7.5 to 3.3, p = 0.45). Even though the GRS for abdominal obesity was associated with an attenuated weight loss response adjusted for age, sex and center (β = -14.6 kg/100 risk alleles, 95% CI -25.4 to -3.8, p = 0.008), it was not significantly associated with weight loss after adjustment for baseline BMI (β = -7.9 kg/100 risk alleles, 95% CI -17.5 to 1.6, p = 0.11). Similarly, the rs1358980-T risk allele was not significantly associated with weight loss (β = -0.8 kg/risk allele, 95% CI -2.2 to 0.6, p = 0.25).

Discussion

GRSs for adiposity derived from large meta-analyses and the rs1358980-T risk allele in the VEGFA locus did not predict weight loss after gastric bypass surgery. The association between a GRS for abdominal obesity and the response to bariatric surgery may be dependent on the association between the GRS and baseline BMI.

What Is Weight Loss After Bariatric Surgery Expressed in Percentage Total Weight Loss (%TWL)? A Systematic Review

Percentage total weight loss (%TWL) might be better than percentage excess weight loss to express weight loss in bariatric surgery. In this systematic review, performed according to the PRISMA statement, results of laparoscopic sleeve gastrectomy (LSG) and Roux-en-Y gastric bypass (LRYGB) are assessed in %TWL. A total of 13,426 studies were screened and 49 included, reporting data of 24,760 patients. The results show that, despite limiting data, LRYGB is favorable over LSG in terms of weight loss in short-term follow-up. Although recent guidelines recommend to use %TWL when reporting outcome in bariatric surgery, this study shows that there is still insufficient quality data in %TWL, especially on LSG. The use of %TWL as the primary outcome measure in bariatric surgery should be encouraged.

Interpretation of laboratory results after gastric bypass surgery: the effects of weight loss and time on 30 blood tests in a 5-year follow-up program

BACKGROUND

Long-term follow-up with blood tests is essential for bariatric surgery to be a successful treatment for obesity and related co-morbidities. Adverse effects, deficiencies, and metabolic improvements need to be controlled.

OBJECTIVE

We investigated the effects of time and weight loss on laboratory results in each postoperative phase after laparoscopic Roux-en-Y gastric bypass (LRYGB).

SETTING

Bariatric center of excellence, general hospital, Netherlands.

METHODS

We retrospectively evaluated results of 30 blood tests, preoperatively and at 6 months, 1 year, 2 years, and 5 years after LRYGB. The 2019 Dutch bariatric chart was used to define weight loss responses as outstanding (>p[percentile curve]+1 SD), average (p+1 SD to p-1 SD), and poor (<p-1 SD). Results are presented with fifth and 95th percentile cutoff values per blood test for each of these 3 weight loss responses at each of the 4 postoperative time intervals. We used ANOVA to determine mutual relations.

RESULTS

Results of 4835 patients were analyzed. Five-year follow-up was 58%. Blood levels of ferritin, mean-corpuscular-volume, thrombocytes, vitamin D, parathyroid-hormone, glycated hemoglobin (HbA1C), triglyceride, total-cholesterol, C-reactive-protein, gamma-glutamyl-transferase, alkaline-phosphatase, creatinine, vitamin B1, and total protein were related with weight loss response. All 30 blood tests were also related with time. For several blood tests, weight loss and time did not only influence median results, but also fifth and 95th percentile cutoff values. Many patients had better vitamin levels after the operation. We observed an increase of parathyroid-hormone and ongoing iron depletion up to 5 years post surgery.

CONCLUSIONS

Presenting results of 30 routine blood tests, including cutoff values based on fifth and 95th percentile, grouped by weight loss response and postoperative time interval after gastric bypass surgery is new. The elaborate tables and graphs could serve as practical guide for proper interpretation of laboratory results in postbariatric surveillance. Results underline the need for long-term follow-up, including blood tests.

Influence of Preoperative Weight Loss on Outcomes of Bariatric Surgery for Patients Under the Enhanced Recovery After Surgery Protocol

INTRODUCTION

The enhanced recovery after surgery (ERAS) protocol, which emphasizes preoperative interventions, is safely implemented in patients undergoing bariatric surgery. Patients are additionally encouraged to achieve weight loss preoperatively. We aimed to identify factors contributing to preoperative weight loss and assess their influence on outcomes of bariatric surgery among patients under the ERAS protocol.

MATERIALS AND METHODS

We reviewed a prospectively created database in two bariatric centers with 909 bariatric patients treated in accordance with ERAS principles. The database included demographic characteristics, factors related to the surgery or perioperative period, and short-term outcomes. Our endpoints included analyses of (1) factors potentially contributing to preoperative weight loss and (2) the influence of preoperative weight loss on short-term outcomes of bariatric treatment.

RESULTS

Diabetes mellitus (p = 0.007), obstructive sleep apnea (p < 0.001), and previous surgery (p = 0.012) were identified as predictors of preoperative weight loss. Steatohepatitis (p < 0.001) and respiratory disorder (p = 0.004) decreased the chance of achieving satisfactory preoperative body mass reduction. Except for operative time, early outcomes of bariatric surgery were not influenced by preoperative weight loss. Patients who achieved preoperative weight loss were less likely to be lost to follow-up (p = 0.023). Postoperative weight loss was better in patients who could lose ≥ 5% total weight preoperatively (p = 0.009).

CONCLUSION

Unsatisfactory preoperative weight loss among patients treated under ERAS principles is not associated with increased risk of complications. Satisfactory preoperative weight loss predicts superior postoperative weight loss and follow-up participation.

Lack of Standard Definitions of Primary and Secondary (Non)responders After Primary Gastric Bypass and Gastric Sleeve: a Systematic Review

Lack of standard definitions of primary and secondary (non)responders after RYGB and SG makes it impossible to compare the literature. The aim was to analyze the different definitions used. MEDLINE® was searched for literature published between 01-07-2014 and 01-07-2017 concerning (1) patients who received a primary RYGB or SG and (2) the outcomes of primary and secondary (non)responders. One hundred twelve out of 650 papers were eligible. Forty out of 47 papers described a definition of weight loss success. Sixty-seven out of 112 papers mentioned weight loss failure of which 42 described a definition, in total 23 different definitions. Weight regain was mentioned in 77 papers; only 21 papers provided a definition. The recent literature regarding definitions of these outcomes is highly inconsistent. To compare the literature international consensus is required.

A test of the stress-buffering hypothesis of social support among bariatric surgery patients

BACKGROUND

The buffering effect of social support against a range of stress-related health outcomes has been well-documented; however, no previous work has examined the applicability of this model to bariatric surgery outcomes.

OBJECTIVES

The present study sought to address whether social support interacts with stress in predicting postsurgical outcomes, as well as whether these associations may vary by sex.

SETTING

Teaching hospital, United States.

METHODS

Data were collected using retrospective chart review (n = 548). Stress, patient sex, and social support were explored as predictors of curvilinear weight loss trajectories during the first year after surgery using growth curve modeling.

RESULTS

Attendance at follow-up appointments was poor, with 250 patients at 6 months and 187 at 12 months. On average, these patients lost 27% of their total weight between baseline and the 12-month follow-up. Overall, weight-related emotional support appeared to be most relevant to weight loss/maintenance in this population; cohabitating with a spouse or significant other and attendance at support group meetings did not predict weight loss or show any significant interactions with stress.

CONCLUSIONS

The present study found only partial support for the stress-buffering model of social support among bariatric surgery patients. Such findings have important implications for assessment and follow-up care after bariatric surgery, as well as for future research in this area.

A Randomised Trial of Text Message Support for Reducing Weight Regain Following Sleeve Gastrectomy

INTRODUCTION

Sleeve gastrectomy (SG) is a common bariatric procedure with high rates of weight regain (WR). Clinicians and patients have identified a lack of follow-up support and maladaptive lifestyle behaviours as potential causes for WR. While text message support has been shown to be effective for weight loss in non-surgical patients, it has not been investigated for reducing WR in bariatric patients.

PURPOSE

To determine the effectiveness of text message support in reducing weight regain following sleeve gastrectomy.

METHODS

A text message intervention was designed. The effectiveness of the intervention was investigated by a randomised trial powered to detect a 15% difference in the primary outcome of percent excess weight loss (84 participants required). Secondary outcomes were the Bariatric Analysis and Reporting System (BAROS) score and patient satisfaction. Outcomes were assessed at 6 and 12 months.

RESULTS

Ninety-five participants were randomised to either standard care or text message support (daily text message for 1 year). While there was no significant difference in the primary outcome at 6 or 12 months, patients who received the intervention tended to have less WR and a significantly better BAROS score at 12 months. Participants who received text message support found it beneficial, would have liked the messages to continue, and felt WR was reduced by having the text message support.

CONCLUSION

Text message support following SG is feasible, may reduce weight regain, improves the BAROS score and is valued by patients.

TRIAL REGISTRATION

NCT02341001.

Sensitivity and Specificity of 50% Excess Weight Loss (50%EWL) and Twelve Other Bariatric Criteria for Weight Loss Success

BACKGROUND

Criteria for bariatric weight loss success are numerous. Most of them are arbitrary. None of them is evidence-based. Our objective was to determine their sensitivity and specificity.

METHODS

Thirteen common bariatric weight loss criteria were compared to a benchmark reflecting the gold standard in bariatric surgery. We used an elaborate baseline BMI-independent weight loss percentile chart, based on retrospective data after laparoscopic Roux-en-Y gastric bypass (LRYGB), performed between 2007 and 2017. Percentile curves p31.6 (patients' expectation), p25 (interquartile range), p15.9 (1 standard deviation (SD) below median), and p10.9 (surgeons' goal) were used as possible cutoff for success to determine true or false positive and negative results beyond 1 year.

RESULTS

We operated 4497 primary LRYGB patients, with mean follow-up 22 (± 1 SD 19; range 0-109) months, 3031 patients with last result ≥ 1 year, 518 ≥ 5 years. For all four cutoff percentile curves for success, specificities were low (2-72%) for criteria < 35 body mass index (BMI), ≥ 25percentage excess BMI loss (%EBMIL), ≥ 50%EBMIL, ≥ 15 percentage total weight loss (%TWL), ≥ 20%TWL, ≥ 25 percentage excess weight loss (%EWL), and high (83-96%) for < 30 BMI. No criterion had > 80% specificity and sensitivity for a cutoff above p15.9. For p15.9, they were both > 80% for criteria ≥ 10 BMI reduction and ≥ 50%EWL, both > 90% for ≥ 25%TWL and ≥ 35 percentage alterable weight loss (%AWL). All criteria had high sensitivities for all cutoff percentile curves (87-100%), except < 30 BMI (65-78%).

CONCLUSIONS

For the first time, common bariatric criteria for weight loss success were systematically validated. Most criteria recognized success very well (high sensitivities), but ≥ 15%TWL, ≥ 20%TWL, < 35BMI, ≥ 25%EWL, ≥ 25%EBMIL, and ≥ 50%EBMIL left too many poor responders unnoticed (low specificities). Bariatric weight loss success is best assessed by comparing results to percentile curve 1 SD below median (p15.9) in a bariatric baseline BMI-independent weight loss percentile chart. Criteria ≥ 35%AWL and ≥ 25%TWL came close to that curve, both with > 90% sensitivity and specificity. Among others, criterion ≥ 50%EBMIL did not.

High Resected Gastric Volume and poorly controlled DM2 in laparoscopic sleeve gastrectomy

BACKGROUND

Our aim is to evaluate the effects of High Resected Gastric Volume(HRGV) on poorly Type 2 Diabetes Mellitus(DM2) after Laparoscopic Sleeve Gastrectomy(LSG).

METHODS

256 patients were divided into two groups according to the RGV: < 1500 mL(Group A: 131 pts) and > 1500 mL(Group B: 147 pts). % excess body mass index loss (%EBMIL), Fasting Blood Glucose (FBG), HbA1c, C peptide were assessed before surgery and at the 3rd day, 6th,12th,24th,36th month after LSG.

RESULTS

A significant difference in %EBMIL between the two groups at 24 and 36 months was found. RGV was not significantly associated with DM2 in the multivariate logistic regression. FBG levels showed no differences between the two groups. A significant decrease of Hb1Ac at 6 and 12 months was found in group B. The C-peptide level showed a significant reduction at 6 and 12 months in group B.

CONCLUSION

The HRGV may play a role in the regulation of the glucose metabolism in the first year after LSG without influence in poorly DM2 control. Further studies are needed to confirm these findings.

Impact of age on postoperative outcomes in bariatric surgery

BACKGROUND

Age is often related to the increase of perioperative complications and reoperation rates. The authors aimed to determine the influence of age on outcomes of most commonly performed bariatric procedures.

METHODS

The retrospective study included patients qualified for primary Laparoscopic Sleeve Gastrectomy (LSG) or Laparoscopic Roux-en-Y Gastric Bypass (LRYGB) in two academic hospitals. Patients were divided into two groups: ≥50 (21.2-26.9%) and <50 (57.6-73.1%) years old. Endpoints assessed the influence of patients' age on the perioperative and the one-year postoperative period.

RESULTS

Operative time was longer in the ≥50-year-old group, but only for LRYGB. There were no differences in the intraoperative adverse events, postoperative morbidity, reoperation and readmission rates between the groups. The risk of port site hernia was increased (OR: 4.23, CI: 1.49-12.06) in the ≥50-year-old group. The mean % of total weight loss 12 months after the bariatric procedure was comparable, but % of excess weight loss and % of excess body mass index loss were lower in the ≥50-year-old group (p = .033 and .032).

CONCLUSIONS

Bariatric surgery is safe and feasible in patients over 50 years old. The weight loss effect can be worse among patients over 50 years old; nevertheless, the treatment should be considered as effective.

Long-term weight loss in laparoscopic sleeve gastrectomy

INTRODUCTION

Laparoscopic sleeve gastrectomy (LSG) has become an option as a bariatric surgical technique. There is a lack of long-term results of this procedure in the literature. The aim of this study is to present weight loss results of LSG for up to 7 years of follow-up.

METHODS

A retrospective series of patients who underwent LSG between 2008 and 2011 was examined. The primary endpoint was weight loss: percentage of excess weight loss (%EWL), percentage of total weight loss (%TWL), and body mass index (BMI) were reported. Failure was defined as %EWL<50%. Multivariate analysis for weight loss was performed. The complications rate was reported.

RESULTS

A total of 148 patients met the inclusion criteria; 76.3% were female. Mean preoperative BMI was 36 ± 4 kg/m². Mean operative time was 89.3 ± 3.2 minutes. Follow-up at 5, 6, and 7 years was 77.7%, 83.3%, and 82.2%, respectively. Mean %EWL and %TWL at 1, 3, 5, and 7 years was 93.2%, 80.7%, 70.6%, and 51.7%, and 27.2%, 23.3%, 20.4%, and 16.3%, respectively. The failure rate was 30.4% at the fifth year and 51.4% at the seventh year. High preoperative BMI was related to worse %EWL (P<0.001) but not to %TWL. Preoperative BMI<35 kg/m² was associated with better %EWL but not with %TWL (P = 0.003). Four leaks (2.7%) and no mortalities were reported.

CONCLUSIONS

LSG is an acceptable surgical technique for weight loss, but in this series, up to one third of the patients fail at the fifth year and half fail in the seventh year. %EWL is better in patients with BMI<35 kg/m², but this difference disappears when we express outcomes with %TWL.