Pharmacokinetic changes post–bariatric surgery: A scoping review

Bariatric surgeries induce structural changes that can alter the absorption of drugs in patients already at risk of polypharmacy. This scoping review aimed to explore pharmacokinetic changes of orally administered drugs in patients post‐bariatric surgery, and assess the quality and level of bias. Electronic databases were searched for articles relating to bariatric surgery and pharmacokinetics published between 1998 and 2019. Pre‐post studies reporting on pharmacokinetic parameters were included, and the Newcastle‐Ottawa Scale was used to assess risk‐of‐bias. A total of 21 studies were included in this review, and changes in absorption were reported in all included studies across 29 drugs. In 11 studies, this change was reported as statistically significant (p<.05), while six reported a nonsignificant change. More drugs exhibited a shorter Tmax and higher Cmax after surgery than otherwise, however changes in AUC were variable. Four studies were assessed as having fair quality while the remainder of the included studies were of good quality and low risk‐of‐bias. Bariatric surgery alters the absorption of drugs and several mechanisms are implicated to be responsible. Short and long‐term monitoring is recommended in patients post‐surgery for clinical changes in response to medications. Future research with a higher number of participants and greater control of variables, such as concurrent medications, malabsorptive disorders, and body composition should be considered.     

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.     

Psychological outcomes following surgical and endoscopic bariatric procedures: A systematic review

Obesity is a leading global epidemic. Bariatric surgery is the only treatment demonstrating substantial long‐term weight loss and medical benefits. However, there is limited research on the psychological outcomes following surgery. Therefore, the primary aim of this study was to systematically review depression, anxiety, and binge eating outcomes at different time points following bariatric surgery and identify whether bariatric surgery significantly reduces psychological symptoms over time. These outcomes were also examined among endoscopic bariatric procedures as a secondary aim. Forty‐eight studies met inclusion criteria. Findings suggested that most patients experience a short‐term reduction in anxiety and depression symptoms from pre‐surgery. Over time, however, these symptoms increase and may even return to pre‐surgery levels. Furthermore, while binge eating was uncommon after surgery, other disordered eating patterns may emerge. Binge eating may also restart over time as the stomach enlarges again. Overall, the complex psychological difficulties faced by individuals with obesity continue after surgery and may contribute to longer‐term weight recidivism. More comprehensive and standardised psychological assessment procedures, including clinical interviews and longer‐term follow‐up, may provide insight into the psychological mechanisms maintaining weight management issues, and may serve as a starting point for improving the long‐term success of patients with obesity.     

Nurse-led intervention for the management of bariatric surgery patients: A systematic review

The prevalence of obesity has become a global health concern, and severe obesity is associated with various chronic diseases and decreased quality of life. Bariatric surgery has shown success in treating obesity. Nevertheless, some patients experience weight regain and unsatisfactory outcomes. Multidisciplinary interventions have been shown to improve postoperative outcomes. Case managers, often specialized nurses, play a crucial role in patient support and coordination of care. However, the diverse design of case-managing interventions hinders the assessment of their success. Thus, the aim of this review is to identify the most successful structural characteristics of case-managing interventions, with or without the support of e-Health, in the process of perioperative management of bariatric surgery patients. A systematic literature review was conducted following the PRISMA guidelines. PubMed, MEDLINE, EBSCOhost, and CINAHL databases were searched for relevant studies published in the last 10 years. Eligible studies included randomized controlled trials, controlled clinical studies, case studies, or observational studies that evaluated perioperative care in bariatric surgery. The PICO framework was used to frame the search strategy. The initial search yielded 225 articles, of which 10 studies met the inclusion criteria. Nurse-led case-managing interventions with a multidisciplinary approach showed positive results in weight loss, physical activity, and quality of life. Patient-centered care models were found to promote adherence to treatment and patient satisfaction. E-Health technologies improved quality of life but not weight loss. The duration of behavioral interventions and the long-term outcomes after surgery remained unclear. Nurse-led case-management interventions, with a focus on behavioral change and multidisciplinary approaches, show promise in improving outcomes in bariatric surgery patients. Patient-centered care models and longer term interventions may contribute to sustained weight loss and better postoperative outcomes. Further research is needed to determine the optimal duration of interventions and the long-term effects on weight maintenance.     

Post‐operative behavioural management in bariatric surgery: a systematic review and meta‐analysis of randomized controlled trials

Recent research has provided evidence that bariatric surgery maximizes long‐term weight loss in patients with severe obesity. However, a substantial number of patients experience poor weight loss outcome and weight regain over time. Post‐operative behavioural management may facilitate long‐term weight control in bariatric surgery population. The objective of this systematic review and meta‐analysis was to determine the effects of post‐operative behavioural management on weight loss following bariatric surgery. Eligible articles were systematically searched in electronic databases. Among the 414 citations, five randomized controlled trials, two prospective and eight retrospective cohort trials analysing behavioural lifestyle interventions and support groups fulfilled the inclusion criteria. The main finding is that behavioural management had a positive effect on weight loss following surgery. In 13 studies, patients receiving behavioural management had greater weight loss than patients receiving usual care or no treatment. A meta‐analysis of five randomized controlled trials suggests greater weight loss in patients with behavioural lifestyle interventions compared with control groups. Post‐operative behavioural management has the potential to facilitate optimal weight loss following bariatric surgery, but conclusions were limited by the small and heterogeneous samples of studies. A more rigorous empirical evaluation on its clinical significance is warranted to improve effectiveness of bariatric surgery.     

Effect of bariatric surgery on circulating FGF‐19: A systematic review and meta‐analysis

Fibroblast growth factor‐19 (FGF‐19) is a gut hormone which interacts with metabolism and is depleted in obesity. There is some indication that the hormone undergoes a resurgence following bariatric surgery (BS), an effect which may contribute to the beneficial outcomes of such procedures. This systematic review and meta‐analysis aims to synthesize the available literature on FGF‐19 levels before and after BS. MEDLINE, Scopus and Web of Science databases were searched, and the effect of different surgical procedures and degrees of body mass index (BMI) reduction on FGF‐19 levels was assessed by DerSimonian and Laird random‐effects model in meta‐analysis and dose–response analyses. This meta‐analysis, which included 474 patients from 25 arms undergoing one of five BS procedures, revealed a significant increase in the levels of circulating FGF‐19 following all‐type BS. Vertical sleeve gastrectomy, duodenal‐jejunal bypass liner and Roux‐en‐Y gastric bypass all significantly increased circulating FGF‐19 levels from baseline. However, gastric banding failed to achieve the same, and in fact, biliopancreatic diversion was associated with decreased circulating FGF‐19. Finally, an inverse association between FGF‐19 and the degree of BMI‐reduction post‐operatively was noted. FGF‐19 is increased by BS and may represent a pharmaceutical target in efforts to reproduce the beneficial effects of BS in a medical setting.     

The influence of bariatric surgery on oral drug bioavailability in patients with obesity: A systematic review

Anatomical changes in the gastrointestinal tract and subsequent weight loss may influence drug disposition and thus drug dosing following bariatric surgery. This review systematically examines the effects of bariatric surgery on drug pharmacokinetics, focusing especially on the mechanisms involved in restricting oral bioavailability. Studies with a longitudinal before‐after design investigating the pharmacokinetics of at least one drug were reviewed. The need for dose adjustment following bariatric surgery was examined, as well as the potential for extrapolation to other drugs subjected to coinciding pharmacokinetic mechanisms. A total of 22 original articles and 32 different drugs were assessed. The majority of available data is based on Roux‐en‐Y gastric bypass (RYGBP) (18 of 22 studies), and hence, the overall interpretation is more or less limited to RYGBP. In the case of the majority of studied drugs, an increased absorption rate was observed early after RYGBP. The effect on systemic exposure allows for a low degree of extrapolation, including between drugs subjected to the same major metabolic and transporter pathways. On the basis of current understanding, predicting the pharmacokinetic change for a specific drug following RYGBP is challenging. Close monitoring of each individual drug is therefore recommended in the early postsurgical phase. Future studies should focus on the long‐term effects of bariatric surgery on drug disposition, and they should also aim to disentangle the effects of the surgery itself and the subsequent weight loss.     

Patient motivations and expectations prior to bariatric surgery: A qualitative systematic review

Bariatric surgery is the most effective treatment for weight loss in individuals with severe and complex obesity. While the extant literature has mostly explored clinical outcomes of surgery, recent research has also examined patients' experiences prior to treatment. This systematic review synthesized findings from qualitative studies investigating patients' motives and expectations prior to undergoing bariatric surgery for weight loss. Twenty‐eight studies published in English involving 580 participants were identified for inclusion. Data extraction and thematic synthesis yielded four global themes: physiological, emotional, cognitive, and interpersonal/environmental. These represented seven subthemes describing patients' presurgery experiences: relationship with food, physical health, activities of living, personal identity, social relations, presurgery information, and beliefs about surgery. In addition to improving physical and medical comorbidities associated with obesity, participants believed that postsurgery weight loss would produce positive psychosocial impacts by strengthening their personal identities, their relationships, and improving their engagement in public and professional life. The complex and widespread nature of the changes patients expected would result from bariatric surgery highlights the importance of providing pretreatment education focused on psychosocial well‐being, as well as concurrent psychological support alongside surgery, to best inform individual treatment selection and clinical practice.     

Obesity and post‐operative complications in patients undergoing non‐bariatric surgery

As the prevalence of obesity continues to rise in society, an increasing number of patients undergoing non‐bariatric surgery will be obese. Obesity is known to increase morbidity and mortality in the general population and thus is perceived as a risk factor for adverse post‐surgical outcomes. This association is not clear‐cut, however, and there is a lack of consensus in the literature on the risk between obesity and specific complications, in particular relating to infection, wound healing, respiratory and venous thromboembolism. The paucity of studies, as well as a lack of consistency of definition of obesity, with an over‐reliance on body mass index rather than body composition analysis, may underlie this confusion. Emerging concepts position central/visceral adipose tissue as potentially key to the pathogenesis of the comorbidities associated with obesity, thus this article reviews emerging research investigating the association between visceral obesity, the metabolic syndrome and resulting post‐operative complications. It is hypothesized that the state of chronic inflammation and dysmetabolism observed in visceral obese patients negatively influences post‐operative outcomes and represents a potential target for pharmaconutrition. The need for further research investigating the influence of visceral adiposity on immune function post surgery and its impact on post‐operative morbidity and mortality is highlighted.     

Prevalence of food addiction among patients undergoing metabolic/bariatric surgery: A systematic review and meta-analysis

Candidates for metabolic/bariatric surgery show a high prevalence of food addiction (FA). However, few studies have investigated FA prevalence after bariatric surgery, especially using longitudinal studies. This systematic review with a meta-analysis aimed to determine pre- and postoperative prevalence of FA among patients undergoing metabolic/bariatric surgery. It included both cross-sectional and longitudinal studies that used the Yale Food Addiction Scale (YFAS). The following databases were searched: MEDLINE, ScienceDirect, LILACS, PsycArticles, CENTRAL, greylit.org , and opengrey.eu. Studies that used the YFAS to evaluate FA in pre- or postoperative patients were included. A random-effects meta-analysis was performed with cross-sectional studies to calculate the weighted prevalence of FA at the pre- and postoperative moments. For longitudinal studies, which measured FA at both time points for the same individuals, absolute prevalence reduction (APR) was calculated. Of the 6626 records, 40 studies were included in the meta-analysis. The preoperative weighted prevalence of FA was 32% (95% CI: 27–37%; 33 groups), whereas the postoperative prevalence was 15% (95% CI: 12–18%; 14 groups). Seven longitudinal studies showed a weighted APR of 26 p.p. (95% CI: 10–41 p.p.). Observational data suggest a reduction in the prevalence of FA among patients that undergo bariatric surgery. Interventional studies are needed to confirm these findings.     

Discontinuation and reduction of asthma medications after metabolic and bariatric surgery: A systematic review and meta-analysis

Obesity is a risk factor for asthma. Metabolic and bariatric surgery (MBS) is a safe and effective treatment option for obesity. Weight reduction via MBS, in turn, may improve asthma outcomes and decrease the need for asthma medications. The aim of the systematic review and meta-analysis is to explore the available evidence focused on the impact of MBS on the improvement of asthma outcomes via the discontinuation and reduction of asthma medications. After a comprehensive search in the PubMed, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) databases, 15 studies, including pre–post MBS data on asthma medication use among adults, were eligible for the systematic review. Thirteen studies reported the proportion of patient who discontinued asthma medication post-MBS and was meta-analyzed using random effects. Results showed 54% patients completely discontinued asthma medications (95% confidence interval 42%–67%, I² = 86.2%, p < 0.001). The average number of asthma medications was also decreased by approximately 22%–46%. MBS provides strong therapeutic benefits for patients with asthma, as evidenced by the complete discontinuation of asthma medications in over 50% of MBS completers. The inference was limited by the small number, variations in follow-up time and rates, and heterogeneity of studies. Studies that include more ethnically diverse participant samples are needed to improve generalizability.     

Genetic variants associated with weight loss and metabolic outcomes after bariatric surgery: A systematic review

The extent to which genetic variations contribute to interindividual differences in weight loss and metabolic outcomes after bariatric surgery is unknown. Identifying genetic variants that impact surgery outcomes may contribute to clinical decision making. This review evaluates current evidence addressing the association of genetic variants with weight loss and changes in metabolic parameters after bariatric surgery. A search was conducted using Medline, Embase, Scopus, Web of Science, and Cochrane Library. Fifty-two eligible studies were identified. Single nucleotide polymorphisms (SNPs) at ADIPOQ (rs226729, rs1501299, rs3774261, and rs17300539) showed a positive association with postoperative change in measures of glucose homeostasis and lipid profiles (n = 4), but not with weight loss after surgery (n = 6). SNPs at FTO (rs11075986, rs16952482, rs8050136, rs9939609, rs9930506, and rs16945088) (n = 10) and MC4R (rs11152213, rs476828, rs2229616, rs9947255, rs17773430, rs5282087, and rs17782313) (n = 9) were inconsistently associated with weight loss and metabolic improvement. Four studies examining the UCP2 SNP rs660339 reported associations with postsurgical weight loss. In summary, there is limited evidence supporting a role for specific genetic variants in surgical outcomes after bariatric surgery. Most studies have adopted a candidate gene approach, limiting the scope for discovery, suggesting that the absence of compelling evidence is not evidence of absence.     

Relationship between dietary macronutrient composition with weight loss after bariatric surgery: A systematic review

This systematic review evaluated the relationship between macronutrient intake and weight loss after bariatric surgery (BS). The MEDLINE/Pubmed, EMBASE, COCHRANE/CENTRAL, and SCOPUS databases were accessed in August 2021 to search for eligible articles: original publications with adults undergoing BS and indicating the relationship between macronutrients and weight loss. Titles that did not meet these criteria were excluded. The review was written according to the PRISMA guide, and the risk of bias was according to the Joanna Briggs manual. Data were extracted by one reviewer and checked by another. Eight articles with 2.378 subjects were included. The studies indicated a positive relationship between weight loss and protein intake after BS. Prioritization of protein followed by carbohydrates with a lower percentage of lipids favors weight loss and increases weight stability after BS. Among the results found, a 1% increase in protein intake raises the probability of obesity remission by 6%, and high-protein diet increase 50% weight loss success. Limitations are the methods of included studies and review process. It is concluded that high-protein intake >60 g a 90 g/day may favor weight loss and maintenance after BS, but it is relevant to balance the other macronutrients.     

Patient experiences of outcomes of bariatric surgery: a systematic review and qualitative synthesis

Although bariatric surgery is the most effective treatment for severe and complex obesity, less is known about its psychosocial impact. This systematic review synthesizes qualitative studies investigating the patient perspective of living with the outcomes of surgery. A total of 2,604 records were screened, and 33 studies were included. Data extraction and thematic synthesis yielded three overarching themes: control, normality and ambivalence. These were evident across eight organizing sub‐themes describing areas of life impacted by surgery: weight, activities of daily living, physical health, psychological health, social relations, sexual life, body image and eating behaviour and relationship with food. Throughout all these areas, patients were striving for control and normality. Many of the changes experienced were positive and led to feeling more in control and ‘normal’. Negative changes were also experienced, as well as changes that were neither positive nor negative but were nonetheless challenging and required adaptation. Thus, participants continued to strive for control and normality in some aspects of their lives for a considerable time, contributing to a sense of ambivalence in accounts of life after surgery. These findings demonstrate the importance of long‐term support, particularly psychological and dietary, to help people negotiate these challenges and maintain positive changes achieved after bariatric surgery.     

Obesity, bariatric surgery and type 2 diabetes--a systematic review

Obesity is endemic in the United States and is closely linked to the development of type 2 diabetes. Both obesity and diabetes are responsible for significant morbidity and mortality. Likewise, both conditions are resistant to treatment. Recent studies have evaluated prevention of type 2 diabetes through intensive lifestyle intervention, while others are examining the impact of bariatric surgery on type 2 diabetes. This article presents an overview of the impact of bariatric surgical and lifestyle interventions on the prevention and treatment of type 2 diabetes. Although studies using a variety of bariatric surgical techniques are included, the focus is on two interventions in particular: the Roux-en-Y gastric bypass and the laparoscopic silicone gastric banding procedure. Outcomes of these procedures are further contrasted with recent lifestyle intervention studies, in particular, the Diabetes Prevention Program study. Gastric bypass studies have been associated with a 99 to 100% prevention of diabetes in patients with IGT and an 80 to 90% clinical resolution of diagnosed early type 2 diabetes. Gastric banding procedures are associated with a lower median (50-60%) clinical remission of type 2 diabetes. Lifestyle intervention studies of obese and glucose-intolerant patients have achieved a 50% reduction in the progression of IGT to diabetes over the short term, with no reported resolution of the disease. Weight loss by any means in the obese patient appears to prevent progression to type 2 diabetes, at least in the short term. Furthermore, sustained weight loss through bariatric surgical intervention is associated both with prevention of progression of IGT and with clinical remission of early type 2 diabetes.     

Early major complications after bariatric surgery in the USA, 2003–2014: a systematic review and meta‐analysis

The effectiveness of bariatric surgery has been well‐studied. However, complications after bariatric surgery have been understudied. This review assesses <30‐d major complications associated with bariatric procedures, including anastomotic leak, myocardial infarction and pulmonary embolism. This review included 71 studies conducted in the USA between 2003 and 2014 and 107,874 patients undergoing either gastric bypass, adjustable gastric banding or sleeve gastrectomy, with mean age of 44 years and pre‐surgery body mass index of 46.5 kg m^?2. Less than 30‐d anastomotic leak rate was 1.15%; myocardial infarction rate was 0.37%; pulmonary embolism rate was 1.17%. Among all patients, mortality rate following anastomotic leak, myocardial infarction and pulmonary embolism was 0.12%, 0.37% and 0.18%, respectively. Among surgical procedures, <30‐d after surgery, sleeve gastrectomy (1.21% [95% confidence interval, 0.23–2.19%]) had higher anastomotic leak rate than gastric bypass (1.14% [95% confidence interval, 0.84–1.43%]); gastric bypass had higher rates of myocardial infarction and pulmonary embolism than adjustable gastric banding or sleeve gastrectomy. During the review, we found that the quality of complication reporting is lower than the reporting of other outcomes. In summary, <30‐d rates of the three major complications after either one of the procedures range from 0% to 1.55%. Mortality following these complications ranges from 0% to 0.64%. Future studies reporting complications after bariatric surgery should improve their reporting quality.