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Journal Watch 08/02/2023

Welcome to our weekly round-up of the latest bariatric and obesity-related papers published in the medical literature. As ever, we have looked far and wide to give you an overview of papers including long-term mortality after bariatric surgery, two studies examining surgery and opioid use, weight gain after RYGB vs SG and the impact of weight-lowering pharmacotherapies on physical activity (please note, log-in maybe required to access the full paper).

Reduction in Long-term Mortality After Sleeve Gastrectomy and Gastric Bypass Compared to Nonsurgical Patients With Severe Obesity

US researchers led by the University of Pittsburgh Medical Center, Pittsburgh, PA, have reported better survival rates following bariatric surgery in Roux-en-Y gastric bypass (RYGB) patients compared to controls.


Writing in the Annals of Surgery, the team compared the long-term risk of mortality among bariatric surgical patients undergoing either RYGB or sleeve gastrectomy (SG) to large, matched, population-based cohorts of patients with severe obesity who did not undergo surgery (from January 2005 to September 2015).


They included 13,900 SG, 17,258 RYGB and 87,965 nonsurgical patients, the five-year follow-up rate was 70.9%, 72.0%, and 64.5%, respectively. RYGB and SG were each associated with a significantly lower risk of all-cause mortality compared to nonsurgical patients at five-years of follow-up (RYGB: HR = 0.43; 95% CI: 0.35,0.54; SG: HR = 0.28; 95% CI: 0.13,0.57) Similarly, RYGB was associated with a significantly lower five-year risk of cardiovascular-(HR = 0.27; 95% CI: 0.20, 0.37), cancer- (HR = 0.54; 95% CI: 0.39, 0.76) and diabetes-related mortality (HR = 0.23; 95% CI:0.15, 0.36). There was not enough follow-up time to assess five-year cause-specific mortality in SG patients, but at three-years follow-up, there was significantly lower risk of cardiovascular- (HR = 0.33; 95% CI:0.19, 0.58), cancer- (HR = 0.26; 95% CI:0.11, 0.59) and diabetes-related (HR = 0.15; 95% CI:0.04, 0.53) mortality for SG patients.


The findings also noted that SG also appears to be associated with lower mortality compared to matched control patients with severe obesity that received usual care. The results can help to inform the trade-offs between long-term benefits and risks of bariatric surgery.


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Opioid Use After Gastric Bypass, Sleeve Gastrectomy or Intensive Lifestyle Intervention

Bariatric surgery was associated with a higher proportion of opioid users and larger total opioid dose, compared to actively treated individuals with obesity, according to a study by Swedish researchers writing in the Annals of Surgery.


The study authors compared opioid use in patients with obesity treated with bariatric surgery vs. adults with obesity who underwent intensive lifestyle modification between August 2007 and September 2015.


During the two-year period before treatment, prevalence of individuals receiving ≥1 opioid prescription was identical in the surgery and lifestyle group. At three years, the prevalence of opioid prescriptions was 14.7% vs. 8.9% in the surgery and lifestyle groups (mean difference 5.9%, 95% confidence interval 5.3–6.4) and at eight years 16.9% vs. 9.0% (7.9%, 6.8–9.0). The difference in mean daily dose also increased over time and was 3.55mg in the surgery group vs. 1.17mg in the lifestyle group at eight years (mean difference [adjusted for baseline dose] 2.30mg, 95% confidence interval 1.61–2.98).


Bariatric surgery was associated with a higher proportion of opioid users and larger total opioid dose, compared to actively treated obese individuals. These trends were especially evident in patients who received additional surgery during follow-up.


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Evaluating the Impact of Metabolic Surgery on Patients with Prior Opioid Use

Nearly half of patients who reported taking opioids prior to metabolic surgery discontinued use at one year, according to investigators from the University of Michigan Medical School, Ann Arbor, MI.


Reporting in SOARD, the researchers sought to determine the impact of metabolic surgery on opioid use behaviours in patients with prior opioid use. Using a statewide metabolic-specific data registry, they identified 16,820 patients who self-reported opioid use before undergoing metabolic surgery between 2006 and 2020 and analysed the 8,506 (50.6%) patients who responded to one-year follow up. They then compared patient characteristics, risk-adjusted 30-day postoperative outcomes, and weight loss between patients who self-reported discontinuing opioid use one year after surgery and those who did not.


Among patients who self-reported using opioids prior to metabolic surgery, 3,864 (45.4%) discontinued use one year after surgery. Predictors of persistent opioid use included an annual income of <$10,000 (p=0.006), Medicare insurance (p<0.0001) and pre-operative tobacco use (p=0.0001). Patients with persistent use were more likely to have a surgical complication (9.6% vs. 7.5%, p=0.0328) and less % excess weight loss (61.6% vs. 64.4%, p<0.0001) vs. patients who discontinued opioids after surgery. There were no differences in the morphine milligram equivalents (MME) prescribed within the first 30 days following surgery between groups (122.3 vs 126.5, p=0.3181).


Targeted interventions aimed at high-risk patients may increase the number of patients who discontinue opioid use after metabolic surgery, the authors concluded.


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Weight recurrence after Sleeve Gastrectomy versus Roux-en-Y gastric bypass: a propensity score matched nationwide analysis

The study carried out by the Dutch Audit for Treatment of Obesity Research Group has found that patients undergoing SG are more likely to experience weight recurrence, and less likely to achieve comorbidity remission vs. patients undergoing RYGB.


The study, published in Surgical Endoscopy, included 19,762 patients – 14,982 RYGB and 4,780 SG patients. After matching 4,693 patients from each group, patients undergoing SG had a higher likelihood on WR up to five-year follow-up compared with RYGB (p<0.01) and less often remission of type 2 diabetes (p<0.01), hypertension (p<0.01), dyslipidaemia (p<0.01), gastroesophageal reflux (p<0.01) and obstructive sleep apnoea syndrome (OSAS) (p<0.01].


Interestingly, patients who experienced WR after SG but maintained ≥ 20%TWL from starting weight, more often achieved HTN (44.7% vs 29.4%), dyslipidaemia (38.3% vs 19.3%), and OSAS (54% vs 20.3%) remission, vs. with patients not maintaining ≥ 20%TWL.


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The effects of weight-lowering pharmacotherapies on physical activity, function and fitness: A systematic review and meta-analysis of randomized controlled trials

Investigators from the Diabetes Research Centre, University of Leicester, Leicester, UK, have reported that improvements in self-reported physical function were observed with weight loss therapy, but the effect on physical activity or objectively measured physical function and fitness could not be determined.


Reporting in Obesity Reviews, their systematic review and meta-analysis of 14 randomised controlled trials (five investigated liraglutide, four semaglutide, three naltrexone/bupropion, and two phentermine/topiramate) included a self-reported measure of physical function, with the pooled findings suggesting an improvement favouring the pharmacotherapy intervention groups (SMD: 0.27; 95% CI: 0.22 to 0.32) and effects generally consistent across different therapies.


The results were also consistent when stratified by the two most commonly used measures: The Short-Form 36-Item Questionnaire (SF-36) (0.24; 0.17 to 0.32) and the Impact of Weight on Quality Of Life-Lite (IWQOL-Lite) (0.29; 0.23 to 0.35). Meta-regression confirmed a significant association between pharmacotherapy induced weight loss and improved physical function for IWQOL-Lite (p = 0.003). None of the studies reported a physical activity outcome, and only one study reported objectively measured cardiorespiratory fitness.


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