Body mass index as a predictor of 1-year outcome in gastric bypass surgery

Development and validation of a scoring system for pre-surgical and early post-surgical prediction of bariatric surgery unsuccess at 2 years

Bariatric surgery (BS) is an effective treatment for morbid obesity. However, a simple and easy-to-use tool for the prediction of BS unsuccess is still lacking. Baseline and follow-up data from 300 consecutive patients who underwent BS were retrospectively collected. Supervised regression and machine-learning techniques were used for model development, in which BS unsuccess at 2 years was defined as a percentage of excess-weight-loss (%EWL) < 50%. Model performances were also assessed considering the percentage of total-weight-loss (%TWL) as the reference parameter. Two scoring systems (NAG-score and ENAG-score) were developed. NAG-score, comprising only pre-surgical data, was structured on a 4.5-point-scale (2 points for neck circumference ≥ 44 cm, 1.5 for age ≥ 50 years, and 1 for fasting glucose ≥ 118 mg/dL). ENAG-score, including also early post-operative data, was structured on a 7-point-scale (3 points for %EWL at 6 months ≤ 45%, 1.5 for neck circumference ≥ 44 cm, 1 for age ≥ 50 years, and 1.5 for fasting glucose ≥ 118 mg/dL). A 3-class-clustering was proposed for clinical application. In conclusion, our study proposed two scoring systems for pre-surgical and early post-surgical prediction of 2-year BS weight-loss, which may be useful to guide the pre-operative assessment, the appropriate balance of patients' expectations, and the post-operative care.

What predicts the unsuccess of bariatric surgery? An observational retrospective study

PURPOSE

Bariatric surgery (BS) has been recognized as an effective treatment for most patients with morbid obesity, but a variable range of patients failed to achieve a successful weight-loss. Controversial data are available about predictors of unsuccess. We aimed to retrospectively assess whether clinical baseline characteristics of patients submitted to sleeve gastrectomy (SL) or gastric bypass (GBP) were associated with unsuccessful weight-loss after 12 and 24-month follow-up.

METHODS

Three hundred patients who underwent BS from the 1st January 2016, with at least 24-months follow-up, were enrolled. Patients were divided according to their percentage of excess weight-loss (%EWL) either < 50% or ≥ 50% after 12 and 24-month follow-up.

RESULTS

None of the patients was lost at follow-up; 56 (18.7%) patients showed a %EWL < 50% at 24 months. Age, neck circumference, obstructive sleep apnea (OSA) were significantly higher, while total cholesterol and %EWL 6-months lower in those with %EWL < 50% at 12-months. Age, neck circumference, male and OSA rates were increased, while %EWL at 6-months lower in patients with %EWL < 50% at 24-months. In a multiple regression model, age (OR = 1.076; 95% CI 1.029-1.125; p = 0.001; OR = 1.066; 1.027-1.107; p < 0.001) and %EWL at 6-months (OR = 0.876; 0.840-0.913; p < 0.001; OR = 0.950; 0.928-0.972; p < 0.001) were associated with %EWL < 50% both at 12- and 24-months, respectively, and neck circumference (OR = 1.142; 1.011-1.289; p = 0.032) with %EWL < 50% at 24-months.

CONCLUSION

Older age, larger neck circumference, and %EWL at 6-months were significantly associated with BS unsuccess, showing almost 90% of those patients an unsuccessful weight-loss early after surgery. Further larger studies with longer follow-up are needed to confirm these results.

Doctor, How Much Weight Will I Lose?-a New Individualized Predictive Model for Weight Loss

Bariatric surgery is an effective treatment for weight loss, but the patient's ability to reach a sustained weight loss depends upon several technical and individual factors. Creating an easy model that adapts bariatric surgery's weight loss goals for each patient is very important for pre-surgery and follow-up evaluations.

Early post-operative psychosocial and weight predictors of later outcome in bariatric surgery: a systematic literature review

This is the first systematic review to synthesize the evidence concerning early post-operative variables predictive of later weight and psychosocial outcomes in bariatric surgery. Eight electronic databases for empirical studies were searched (1954 to 2016). Most of the 39 included studies reported solely on weight outcomes; eating and psychosocial outcomes were less common. A better early weight loss trajectory was the most consistent predictor of more successful medium-term weight outcome (≤24 months); however, its relationship to longer term weight loss maintenance is less certain. Early eating adaptation may be associated with later weight loss, but further research is needed. Evidence is lacking for associations between early adherence or early psychosocial variables and later outcome. In particular, the relationship between early post-operative depression and later weight remains unclear. Little research has considered early prediction of later eating or psychosocial outcomes. Consideration of mediating or moderating relationships is lacking. The body of evidence is limited, and synthesis is hampered by heterogeneity in the type and time at which predictors and outcomes are measured and quality of statistical reporting. Further research on prospective prediction of bariatric surgery outcome is needed to guide early post-operative intervention for those at greatest risk of poor outcomes.

Dietary and psych predictors of weight loss after gastric bypass

BACKGROUND

Identifying severely obese patients who will succeed after bariatric surgery remains challenging. Although numerous studies have attempted to identify preoperative patient characteristics associated with weight loss, the roles of many dietary and psychological characteristics are unclear. The purpose of this study was to examine preoperative dietary and psychological predictors of successful weight loss after bariatric surgery.

MATERIALS AND METHODS

This retrospective cohort study included all patients who underwent laparoscopic Roux-en-Y gastric bypass from September 2011-June 2013 at a single institution (n = 124). Patient demographics, comorbidities, dietary and psychological factors, and weight loss outcomes were extracted from the electronic medical record. Bivariate associations between these factors and successful weight loss (≥50% excess body weight) were examined. Factors significant at P ≤ 0.1 were included in a multivariate logistic regression model.

RESULTS

On bivariate analysis, absence of either type 2 diabetes or hypertension, preoperative weight <270 lbs, no intentional past weight loss >50 lbs, no previous purging or family history of obesity, and no soda consumption preoperatively were associated with successful weight loss (P < 0.1). On multivariate analysis, successful weight loss was inversely associated with the presence of type 2 diabetes (odds ratio [OR], 0.22, 95% confidence interval [CI], 0.06-0.73), maximum intentional past weight loss >50 lbs (OR, 0.12 [95% CI, 0.04-0.43]), and decreasing soda consumption by >50% (OR, 0.27 [95% CI, 0.08-0.99]).

CONCLUSIONS

Patients with type 2 diabetes mellitus, significant previous weight loss, and poor soda consumption habits are more likely to experience suboptimal weight loss after bariatric surgery. Additional preoperative counseling and close postoperative follow-up is warranted for these patients.

Measurement of disordered eating in bariatric surgery candidates: a systematic review of the literature

Symptoms of disordered eating are common among patients seeking bariatric surgery, and assessment of eating pathology is typical in pre-surgical evaluations. A systematic review was conducted to evaluate the definitions, diagnostic criteria and measures used to assess disordered eating in adults seeking bariatric surgery. The review identified 147 articles featuring 34 questionnaires and 45 interviews used in pre-surgical assessments. The Questionnaire on Eating and Weight Patterns Revised and the Structured Clinical Interview for DSM were the most frequently used questionnaire and interview respectively. Variations to pre-surgical diagnostic criteria included changes to the frequency and duration criteria for binge eating, and inconsistent use of disordered eating definitions (e.g., grazing). Results demonstrate a paucity of measures designed specifically for an obese sample, and only 24% of questionnaires and 4% of interviews used had any reported psychometric evaluation in bariatric surgery candidates. The psychometric data available suggest that interview assessments are critical for accurately identifying binge episodes and other diagnostic information, while self-report questionnaires may be valuable for providing additional information of clinical utility (e.g., severity of eating, shape and weight-related concerns). Findings highlight the need for consensus on disordered eating diagnostic criteria and psychometric evaluation of measures to determine whether existing measures provide a valid assessment of disordered eating in this population. Consistent diagnosis and the use of validated measures will facilitate accurate identification of disordered eating in the pre-surgical population to enable assessment of suitability for surgery and appropriate targeting of treatment for disordered eating to optimise treatment success.

Advantages of percent weight loss as a method of reporting weight loss after Roux-en-Y gastric bypass

OBJECTIVE

Although Roux-en-Y gastric bypass (RYGB) is an effective treatment for severe obesity, weight loss (WL) after this operation is highly variable. Accurate predictors of outcome would thus be useful in identifying those patients who would most benefit from this invasive therapy. WL has been characterized using several different metrics, including the number of BMI units lost (ΔBMI), percent baseline WL (%WL), and percent excess body WL (%EBWL). To identify clinically relevant predictors most sensitively, it is necessary to avoid confounding by other factors, including preoperative BMI (pBMI), the strongest known predictor of RYGB-induced WL.

DESIGN AND METHODS

To determine the WL measure least associated with pBMI, outcomes of 846 patients undergoing RYGB were analyzed.

RESULTS

Patients in this cohort had an average pBMI of 50.0 kg/m(2) at baseline. At weight nadir, they lost an average 19.4 kg/m(2), 38.7% WL, and 81.2% EBWL. pBMI was strongly and positively associated with ΔBMI at both 1 year (r = 0.56, P = 4.7 × 10(-51)) and nadir (r = 0.58, P = 2.8 × 10(-77)) and strongly but negatively associated with %EBWL at 1 year (r = -0.52, P = 3.8 × 10(-44)) and nadir (r = -0.45, P = 7.2×10(-43)). In contrast, pBMI was not significantly associated with %WL at 1 year (r = 0.04, P = 0.33) and only weakly associated at nadir (r = 0.13, P = 0.0002).

CONCLUSIONS

Of the metrics examined, %WL is the parameter describing WL after RYGB least influenced by pBMI. It thus improves comparison of WL outcomes across studies of patients undergoing surgery and facilitates the most sensitive identification of novel predictors of surgery-induced WL. We therefore is recommend that %WL be adopted more broadly in reporting weight loss after RYGB.

Roux-en-Y gastric bypass for morbid obesity: what are the preoperative predictors of weight loss?

Obesity has become an increasingly important health problem over the past 30 years. Presently around a quarter of the UK adult population are obese and this figure is set to increase further in the coming decades. The health consequences of obesity on multiple body systems have been well established as has the financial cost of the condition to both the individuals affected as well as to society as a whole. Bariatric surgery has been shown to be the only long term effective solution in terms of sustained weight loss and comorbidity resolution. The commonest bariatric procedure in the UK is the Roux-en-y gastric bypass which consistently results in the loss of 70%-80% of excess bodyweight. Results however are variable and in order to optimise resource allocation and avoid exposing patients unlikely to benefit from surgery to its inherent risks, much research has been done to try to identify those patients most likely to obtain a good result. The only factor which has been subjected to meta-analysis is that of preoperative weight loss which shows a positive association with postoperative weight loss following bypass surgery. Although the remaining data are not based on level 1 evidence those other preoperatively identifiable factors which are associated with an improved outcome include Caucasian or Hispanic ethnicity, higher educational status, non-shift-work working patterns, female gender and divorced or single marital status. Similarly increased levels of preoperative physical activity and an absence of binge eating behaviour are consistent with a favourable result whereas increased age, smoking and other socioeconomic factors have not been shown to have a significant impact. Conversely diabetes mellitus seems to have a slight negative correlation with postoperative weight loss; however, a history of sexual abuse or psychiatric illness has not been shown to have a lasting influence.

Age as a long-term prognostic factor in bariatric surgery

OBJECTIVE

: To analyze the potential effects of preoperative age on postoperative weight loss in patients who underwent Roux-en-Y gastric bypass (RYGBP) with long-term follow-up data.

BACKGROUND

: The reasons for individual differences in surgically induced weight loss are not completely understood. To date, there are no available studies specifically aimed at analyzing the effects of age on weight loss in patients undergoing the same operation and with long-term follow-up data.

METHODS

: Retrospective analysis of prospectively collected data for all patients who underwent RYGBP between 2006 and 2010. To evaluate weight loss, we used preoperative and follow-up body mass index (BMI), analyzed by the mixed-effects linear model for repeated measures. To evaluate age effects, patients were classified in quartiles (≤35 years, 36-42 years, 43-51 years, ≥52 years).

RESULTS

: A total of 489 patients entered the study; preoperatively, the younger group showed a significantly higher BMI (mean BMI: 48.2 in patients aged ≤35 years, 46.9 in 36-42 years, 45.5 in 43-51 years, 45.7 in ≥52 years, P = 0.014) and a higher percentage of super-obesity (41.6% among patients aged ≤35 years, 28.1% among 36-42 years, 27.6% among 43-51 years, 28.3% among ≥ 52 years, P = 0.047). In spite of this, younger patients experienced a significantly greater and prolonged BMI decrease during the entire follow-up period and the BMI trend over time resulted significantly modified according to age quartiles (P = 0.036).

CONCLUSIONS

: This study provides a new prognostic factor in bariatric surgery: patient age. Because advanced age represents a risk factor for complications and mortality, and given that bariatric surgery may not be as effective in older patients compared to younger subjects, we believe that surgical indications in patients older than 50 years should be carefully weighed up.

Preoperative predictors of weight loss following bariatric surgery: systematic review

BACKGROUND

Obesity affects 32% of adults in the USA. Surgery generates substantial weight loss, but 20-30% fails to achieve successful weight loss. Our objective was to identify preoperative psychosocial factors associated with weight loss following bariatric surgery.

METHODS

We performed a literature search of PubMed® and the Cochrane Database of Reviews of Effectiveness between 1988 and April 2010. Articles were screened for bariatric surgery and weight loss if they included a preoperative predictor of weight loss: body mass index (BMI), preoperative weight loss, eating disorders, or psychiatric disorder/substance abuse. One thousand seven titles were reviewed, 534 articles screened, and 115 included in the review.

RESULTS

Factors that may be positively associated with weight loss after surgery include mandatory preoperative weight loss (7 of 14 studies with positive association). Factors that may be negatively associated with weight loss include preoperative BMI (37 out of 62 studies with negative association), super-obesity (24 out of 33 studies), and personality disorders (7 out of 14 studies). Meta-analysis revealed a decrease of 10.1% excess weight loss (EWL) for super-obese patients (95% confidence interval (CI) [3.7-16.5%]), though there was significant heterogeneity in the meta-analysis, and an increase of 5.9% EWL for patients with binge eating at 12 months after surgery (95% CI [1.9-9.8%]).

CONCLUSIONS

Further studies are necessary to investigate whether preoperative factors can predict a clinically meaningful difference in weight loss after bariatric surgery. The identification of predictive factors may improve patient selection and help develop interventions targeting specific needs of patients.

Predictive factors of weight loss 1 year after laparoscopic gastric bypass in obese patients

BACKGROUND

Substantial weight loss is achieved in majority of severely obese subjects undergoing laparoscopic gastric bypass (LGBP) but some fail to obtain expected results. Our aim was to identify preoperative factors that could influence weight loss (WL) 1 year after LGBP.

METHODS

We studied the predictive value of clinical, biological, and dietary preoperative factors on weight loss in obese patients referred for LGBP. WL was assessed according to mean absolute weight loss (AWL) and mean percent excess weight loss (%EWL) 1 year after LGBP.

RESULTS

One hundred twenty-three subjects were included (112 women, age 42 ± 10 years; weight 127 ± 23 kg; BMI 47 ± 8 kg/m(2)). Mean AWL was 39.4 ± 10.5 kg at 1 year, corresponding to a mean %EWL of 70.5 ± 21.2%. AWL was positively correlated with initial weight, BMI, and energy intake and negatively with age, female sex, and treatment for hypertension and diabetes. %EWL was negatively correlated with initial weight, BMI, and positively correlated with triglycerides and ferritinemia. In multivariate analysis, %EWL was negatively correlated only with initial BMI (p < 0.001). AWL was positively correlated with initial BMI and male sex (both p < 0.001), and negatively correlated with protein intake (p = 0.039) and treatment for diabetes (p = 0.021), but not with biomarkers of diabetes and insulin resistance.

CONCLUSION

Initial BMI appears to be a strong determinant of individual WL, but predictive factors differ when WL was expressed as %EWL or AWL. The treatment of diabetes rather than diabetes itself appears to affect WL.