A Clinical-Genetic Score for Predicting Weight Loss after Bariatric Surgery: The OBEGEN Study

Use of polygenic risk scores to assess weight loss after bariatric surgery: a five-year follow-up study

BACKGROUND

Bariatric surgery is currently the most effective long-term treatment for severe obesity. However, the interindividual variability observed in surgical outcomes suggests a moderating effect of several factors, including individual genetic background. Our goal was to investigate the contribution of the genetic architecture of BMI to the variability in weight loss outcomes after bariatric surgery.

METHODS

A total of 106 patients with severe obesity who underwent Roux-en-Y gastric bypass or sleeve gastrectomy were followed up for five years. Changes in body mass index (BMIchange) and percentage of total weight loss (%TWL) were evaluated during the postoperative period. Polygenic risk scores including 50 genetic variants were calculated for each participant to determine their individual genetic risk for high BMI based on a previous GWAS. Generalized estimating equation models were used to study the role of the individual's polygenic score, as well as other factors, on BMIchange and %TWL in the long term after surgery.

RESULTS

We found an effect of the polygenic score on %TWL and BMIchange, where subjects with lower scores had better outcomes after surgery than those with higher scores. Furthermore, when analyzing only patients who underwent Roux-en-Y gastric bypass, these results were replicated showing greater weight loss after surgery for those with lower polygenic scores.

DISCUSSION

These results indicate that genetic background assessed with polygenic risk scores, along with other individual factors such as sex, age, and preoperative BMI, has an impact on bariatric surgery outcomes and could represent a useful tool for estimating surgical outcomes in advance.

Genetic risk score based on obesity-related genes and progression in weight loss after bariatric surgery: a 60-month follow-up study

BACKGROUND

Obesity is a polygenic multifactorial disease. Recent genome-wide association studies have identified several common loci associated with obesity-related phenotypes. Bariatric surgery (BS) is the most effective long-term treatment for patients with severe obesity. The huge variability in BS outcomes between patients suggests a moderating effect of several factors, including the genetic architecture of the patients.

OBJECTIVE

To examine the role of a genetic risk score (GRS) based on 7 polymorphisms in 5 obesity-candidate genes (FTO, MC4R, SIRT1, LEP, and LEPR) on weight loss after BS.

SETTING

University hospital in Spain.

METHODS

We evaluated a cohort of 104 patients with severe obesity submitted to BS (Roux-en-Y gastric bypass or sleeve gastrectomy) followed up for >60 months (lost to follow-up, 19.23%). A GRS was calculated for each patient, considering the number of carried risk alleles for the analyzed genes. During the postoperative period, the percentage of excess weight loss total weight loss and changes in body mass index were evaluated. Generalized estimating equation models were used for the prospective analysis of the variation of these variables in relation to the GRS.

RESULTS

The longitudinal model showed a significant effect of the GRS on the percentage of excess weight loss (P = 1.5 × 10-5), percentage of total weight loss (P = 3.1 × 10-8), and change in body mass index (P = 7.8 × 10-16) over time. Individuals with a low GRS seemed to experience better outcomes at 24 and 60 months after surgery than those with a higher GRS.

CONCLUSION

The use of the GRS in considering the polygenic nature of obesity seems to be a useful tool to better understand the outcome of patients with obesity after BS.

Plasma SHBG Levels as an Early Predictor of Response to Bariatric Surgery

BACKGROUND

Obesity is a growing global health problem, and currently, bariatric surgery (BS) is the best solution in terms of sustained total weight loss (TWL). However, a significant number of patients present weight regain (WR) in time. There is a lack of biomarkers predicting the response to BS and WR during the follow-up. Plasma SHBG levels, which are low in obesity, increase 1 month after BS but there is no data of plasma SHBG levels at long term. We performed the present study aimed at exploring the SHBG role in predicting TWL and WR after BS.

METHODS

Prospective study including 62 patients with obesity undergoing BS. Anthropometric and biochemical variables, including SHBG were analyzed at baseline, 1, 6, 12, and 24 months; TWL ≥ 25% was considered as good BS response.

RESULTS

Weight loss nadir was achieved at 12 months post-BS where maximum SHBG increase was reached. Greater than or equal to 25% TWL patients presented significantly higher SHBG increases at the first and sixth months of follow-up with respect to baseline (100% and 150% respectively, p = 0.025), than < 25% TWL patients (40% and 50% respectively, p = 0.03). Also, these presented 6.6% WR after 24 months. The first month SHBG increase predicted BS response at 24 months (OR = 2.71; 95%CI = [1.11-6.60]; p = 0.028) and TWL in the 12th month (r = 0.330, p = 0.012) and the WR in the 24th (r =  - 0.301, p = 0.028).

CONCLUSIONS

Our results showed for the first time that increase in plasma SHBG levels within the first month after BS is a good predictor of TWL and WR response after 2 years.

Towards precision medicine in bariatric surgery prescription

Obesity is a complex, multifactorial and chronic disease. Bariatric surgery is a safe and effective treatment intervention for obesity and obesity-related diseases. However, weight loss after surgery can be highly heterogeneous and is not entirely predictable, particularly in the long-term after intervention. In this review, we present and discuss the available data on patient-related and procedure-related factors that were previously appointed as putative predictors of bariatric surgery outcomes. In addition, we present a critical appraisal of the available evidence on which factors could be taken into account when recommending and deciding which bariatric procedure to perform. Several patient-related features were identified as having a potential impact on weight loss after bariatric surgery, including age, gender, anthropometrics, obesity co-morbidities, eating behavior, genetic background, circulating biomarkers (microRNAs, metabolites and hormones), psychological and socioeconomic factors. However, none of these factors are sufficiently robust to be used as predictive factors. Overall, there is no doubt that before we long for precision medicine, there is the unmet need for a better understanding of the socio-biological drivers of weight gain, weight loss failure and weight-regain after bariatric interventions. Machine learning models targeting preoperative factors and effectiveness measurements of specific bariatric surgery interventions, would enable a more precise identification of the causal links between determinants of weight gain and weight loss. Artificial intelligence algorithms to be used in clinical practice to predict the response to bariatric surgery interventions could then be created, which would ultimately allow to move forward into precision medicine in bariatric surgery prescription.

Abdominal Obesity Genetic Variants Predict Waist Circumference Regain After Weight Loss

Although many individuals are able to achieve weight loss, maintaining this loss over time is challenging. We aimed to study whether genetic predisposition to general or abdominal obesity predicts weight regain after weight loss. We examined the associations between genetic risk scores for higher BMI and higher waist-to-hip ratio adjusted for BMI (WHRadjBMI) with changes in weight and waist circumference up to 3 years after a 1-year weight loss program in participants (n = 822 women, n = 593 men) from the Look AHEAD (Action for Health in Diabetes) study who had lost ≥3% of their initial weight. Genetic predisposition to higher BMI or WHRadjBMI was not associated with weight regain after weight loss. However, the WHRadjBMI genetic score did predict an increase in waist circumference independent of weight change. To conclude, a genetic predisposition to higher WHRadjBMI predicts an increase in abdominal obesity after weight loss, whereas genetic predisposition to higher BMI is not predictive of weight regain. These results suggest that genetic effects on abdominal obesity may be more pronounced than those on general obesity during weight regain.

ARTICLE HIGHLIGHTS

Nearly all individuals who intentionally lose weight experience weight regain. Individuals with a higher genetic risk for abdominal adiposity experience increased regain in waist circumference after weight loss. Genetic predisposition to higher BMI does not predict weight regain after weight loss.

The Influence of Single Nucleotide Polymorphisms On Body Weight Trajectory After Bariatric Surgery: A Systematic Review

PURPOSE OF REVIEW

To conduct a systematic review to summarize the results of studies on this subject and to identify whether single nucleotide polymorphisms (SNPs) are good prognostic markers for body weight trajectory after bariatric surgery.

RECENT FINDINGS

A considerable number of events can influence the body weight trajectory after bariatric surgery, and in the post-genomic era, genetic factors have been explored. This study is registered with PROSPERO (CRD42021240903). SNPs positively associated with poor weight loss after bariatric surgery were rs17702901, rs9939609, rs1360780, rs1126535, rs1137101, rs17782313, rs490683, and rs659366. Alternatively, SNPs rs2229616, rs5282087, rs490683, rs9819506, rs4771122, rs9939609, rs4846567, rs9930506, rs3813929, rs738409, rs696217, rs660339, rs659366, rs6265, rs1801260, and rs2419621 predicted a higher weight loss after bariatric surgery. Six studies performed with a genetic risk score (GRS) model presented significant associations between GRS and outcomes following bariatric surgery. This systematic review shows that, different SNPs and genetic models could be good predictors for body weight trajectory after bariatric surgery. Based on the results of the selected studies for this Systematic Review is possible to select SNPs and metabolic pathways of interest for the GRS construction to predict the outcome of bariatric surgery to be applied in future studies.

Combined Effect of Genetic Variants on Long-Term Weight Response after Bariatric Surgery

The pathophysiology of body weight control involves complex interactions between hormonal, environmental, behavioral and genetic factors. The purpose of this study was to analyze the association between single nucleotide polymorphisms (SNPs) of 13 genes encoding gastrointestinal peptides, their receptors or the proteins involved in their expression, with long-term weight response in a cohort of 375 patients undergoing bariatric surgery (BS). To evaluate weight response, we combined several variables to define specific response phenotypes six years after surgery. The study protocol was registered in ISRCTN (ID80961259). The analysis of the selected SNPs was performed via allelic discrimination using Taqman^® probes (Applied Biosystems, Foster City, CA, USA). The genotype association study was performed using the SNPstat program, with comparisons adjusted for sex, age, initial body mass index, type 2 diabetes, hypertension diagnosis and the type of surgery. We identified eight genetic variants associated with the weight response to BS, independently of the presurgery patient profile and the type of surgical technique, from which we calculated the unweighted risk score (RS) for each phenotype. The highest scoring category in each RS was significantly associated with lower weight loss (p = 0.0001) and greater weight regain (p = 0.0012) at the end of the follow-up.

Parental Obesity Predisposition and Age of Onset Associate with Poor Response to Bariatric and Metabolic Surgery

INTRODUCTION

Parental predisposition and age of onset may be independently associated with 1-year total weight loss (TWL) failure (< 20%) after metabolic-bariatric surgery (MBS).

METHODS

This cohort study includes all cases of the German StuDoQ|MBE register (2015-2019) with data on parental predisposition, obesity onset, and at least 1-year follow up after primary MBS procedures (n = 14,404). We provide descriptive statistics of the cohort in terms of the main outcome and 1-year TWL failure, and provide characteristics of surgery type subgroups. Finally, we provide a multivariate logistic regression model of 1-year TWL failure.

RESULTS

58.8% and 45.7% of patients reported maternal and paternal predisposition for obesity, respectively. Average onset of obesity was 15.5 years and duration of disease 28.3 years prior to MBS. SG is the most frequently performed procedure (47.2%) followed by RYGB (39.7%) and OAGB (13.1%). Mean 1-year TWL is 32.7 ± 9.3%, and 7.8% (n = 1,119) of patients show TWL failure (< 20%). Multivariate analysis shows independent association of early onset of obesity (< 18 years), male sex, age at operation, pre-operative BMI, pre-operative weight loss, sleeve gastrectomy (SG), and type 2 diabetes (T2D) with 1-year TWL failure (p < 0.001).

CONCLUSION

The proportions of MBS patients that report on paternal and maternal predisposition for obesity are 45.7% and 58.8% respectively, and average age at onset is 15.5 years. 7.8% of patients do not meet current target criteria of successful response to surgery at 1 year. Early onset, male sex, age at operation, pre-operative BMI, pre-operative weight loss, SG, and T2D are independently associated with weight loss failure.

Changes in Eating Behaviors and Their Associations with Weight Loss in Japanese Patients Who Underwent Laparoscopic Sleeve Gastrectomy

BACKGROUND

Metabolic and bariatric surgery (MBS) has been established to provide long-term weight loss in severe obesity. In this study, we investigated the factors that affect post-operative weight loss, with a particular focus on changes in eating behaviors.

METHODS

Time-course changes in body weight and eating behaviors were examined in 49 Japanese patients who underwent laparoscopic sleeve gastrectomy from the first visit to 12 months after surgery. Each eating behavior was evaluated via the questionnaire of the Japan Society for the Study of Obesity.

RESULTS

Pre-operative weight reduction mediated by dietary and lifestyle interventions showed significant positive correlations with weight loss outcomes at 12 months after surgery. We observed significant decreases in scores for most of the eating behaviors 12 months after surgery. However, "emotional eating behavior" scores declined temporarily in the early post-operative period of one month but thereafter returned to the pre-operative level at 12 months. Furthermore, increases in the scores for "emotional eating behavior" and "sense of hunger" from 1 to 12 months post-operatively were significantly associated with poor weight loss.

CONCLUSIONS

Our results demonstrate the beneficial effects of MBS on obesity-related eating behaviors, as well as highlighting "emotional eating behavior" as requiring particular attention.

Definition, Mechanisms and Predictors of Weight Loss Failure After Bariatric Surgery

It has been proven that surgery is more effective than non-surgical treatment in obese patients. However, this approach has several disadvantages, especially long-term weight loss. Weight loss failures can be broadly classified into two categories; insufficient weight loss (poor responder) and weight regain. However, a unified definition has not been established yet for each category, and there is no clear standard for the post-surgery time point to be used to assess weight loss failure. In addition, analyzing factors that contribute to weight loss failure will lead to strategies for reducing it. Therefore, many researchers have been interested in this subject and have published conflicting results. This review presents a definition for and describes the mechanisms and predictors of weight loss failure after bariatric surgery.

Higher Waist Hip Ratio Genetic Risk Score Is Associated with Reduced Weight Loss in Patients with Severe Obesity Completing a Meal Replacement Programme

Background: A better understanding of the influence of genetic factors on the response to lifestyle interventions in people with obesity may allow the development of more personalised, effective and efficient therapeutic strategies. We sought to determine the influence of six obesity-related genetic risk scores on the magnitude of weight lost by patients with severe obesity who completed a dietary intervention. Methods: In this single-centre prospective cohort study, participants with severe and complicated obesity who completed a 24-week, milk-based meal replacement programme were genotyped to detect the frequency of common risk alleles for obesity and type 2 diabetes-related traits. Genetic risk scores (GRS) for six of these traits were derived. Participants with a potentially deleterious monogenic gene variant were excluded from the analysis. Results: In 93 patients completing the programme who were not carrying a known obesity-related gene mutation, 35.5% had diabetes, 53.8% were female, mean age was 51.4 ± 11 years, mean body mass index was 51.5 ± 8.7 and mean total weight loss percent at 24 weeks was 16 ± 6.3%. The waist-hip ratio (WHR) GRS was inversely associated with percentage total weight loss at 24 weeks (adjusted β for one standard deviation increase in WHR GRS -11.6 [-23.0, -0.3], p = 0.045), and patients in the lowest tertile of WHR GRS lost more weight. Conclusions: Patients with severe and complicated obesity with a genetic predisposition to central fat accumulation had less weight loss in a 24-week milk-based meal replacement programme, but there was no evidence for influence from the five other obesity-related genetic risk scores on the response to dietary restriction.

A review on the beneficial effects of bariatric surgery in the management of obesity

INTRODUCTION

Obesity is a chronic disease with a complex interplay of multiple factors such as genetic, metabolic, behavioral, and environmental factors. The management of obesity includes; lifestyle modification, psychological therapy, pharmacological therapy, and bariatric surgery. To date, bariatric surgery is the most effective treatment for obesity by offering a long-term reduction in weight, remission of obesity-related complications, and improving quality of life. However, bariatric surgery is not equally effective in all patients. Thus, if we can predict who would benefit most, it will improve the risk versus benefit ratio of having surgery.

AREAS COVERED

In this narrative review, we explore the question on who will benefit the most from bariatric surgery by examining the recent evidence in the literature. In addition, we investigate the predisposing predictors of bariatric surgery response. Finally, we offer the best strategies in the clinic to explain the potential benefits of bariatric surgery to patients.

EXPERT OPINION

Bariatric surgery is an effective obesity management approach. Despite its efficacy, considerable variation of individual response exists. Thus, it is important to recognize patients that will benefit most, but at present very few predictors are available which can be clinically useful.

Influence of CLOCK Gene Variants on Weight Response after Bariatric Surgery

The Circadian Locomotor Output Cycles Kaput (CLOCK) gene has been linked to metabolic dysfunction and obesity. The purpose of this study was to analyze the association between single nucleotide polymorphisms (SNPs) of CLOCK gene with obesity and with long-term weight response after different bariatric surgery (BS) techniques. The cohort includes 375 patients with morbid obesity (MO) and 230 controls. In the association study of SNPs with weight response we combined several variables as phenotype at 6 years after surgery. The study protocol was registered in ISRCTN (ID80961259). The analysis of the selected SNPs was performed by allelic discrimination using Taqman^® probes. The genotype association study was performed using the SNPStats program, with comparisons adjusted for sex, age, initial Body Mass Index, type 2 diabetes and hypertension diagnosis, and type of surgery. In the case-control study two of three SNPs were significantly associated with MO. The variant rs1801260 had a protective effect for MO whereas the TT genotype of rs3749474 variant had the strongest association with MO (OR = 2.25 (1.39–3.66); p = 0.0006). In the linear regression analysis both variants showed significant association with long-term weight loss and weight regain after BS, independently of the pre-surgery patient profile.

Neurohormonal Changes in the Gut–Brain Axis and Underlying Neuroendocrine Mechanisms following Bariatric Surgery

Obesity is a complex, multifactorial disease that is a major public health issue worldwide. Currently approved anti-obesity medications and lifestyle interventions lack the efficacy and durability needed to combat obesity, especially in individuals with more severe forms or coexisting metabolic disorders, such as poorly controlled type 2 diabetes. Bariatric surgery is considered an effective therapeutic modality with sustained weight loss and metabolic benefits. Numerous genetic and environmental factors have been associated with the pathogenesis of obesity, while cumulative evidence has highlighted the gut–brain axis as a complex bidirectional communication axis that plays a crucial role in energy homeostasis. This has led to increased research on the roles of neuroendocrine signaling pathways and various gastrointestinal peptides as key mediators of the beneficial effects following weight-loss surgery. The accumulate evidence suggests that the development of gut-peptide-based agents can mimic the effects of bariatric surgery and thus is a highly promising treatment strategy that could be explored in future research. This article aims to elucidate the potential underlying neuroendocrine mechanisms of the gut–brain axis and comprehensively review the observed changes of gut hormones associated with bariatric surgery. Moreover, the emerging role of post-bariatric gut microbiota modulation is briefly discussed.