Metabolic, renal, and nutritional consequences of bariatric surgery: implications for the clinician

Bariatric Surgery Before Elective Anterior Cervical Discectomy and Fusion (ACDF) in Obese Patients Is Associated With Reduced Risk of 90-Day Postoperative Complications and Readmissions

STUDY DESIGN

This was a national database study.

OBJECTIVE

The objective of this study was to assess the impact of prior bariatric surgery (BS) on altering 90-day postoperative outcomes following elective anterior cervical discectomy and fusions (ACDFs).

SUMMARY OF BACKGROUND DATA

Though obesity has previously been shown to be linked with adverse outcomes following elective spine surgical procedures, the effectiveness of weight-loss strategies such as BS has not been explored.

METHODS

The PearlDiver program was used to query the 2007-2013 100% Medicare Standard Analytical Files (SAF100) for patients undergoing an elective ACDF. The study cohort was divided into 2 groups-(1) obese ACDF patients (body mass index ≥35 kg/m 2 ) receiving a BS procedure within 2 years before an ACDF and (2) obese ACDF patients (body mass index ≥35 kg/m 2 ) without a known history of a BS procedure within the last 2 years. Multivariate regression analyses were used to assess the impact of a BS procedure on postoperative outcomes following ACDF while adjusting for age, sex, region, and Elixhauser Comorbidity Index.

RESULTS

A total of 411 ACDF patients underwent BS within the 2 years before an ACDF. Multivariate analysis showed that undergoing BS before an elective ACDF was associated with a significantly reduced risk of pulmonary complications [odds ratio (OR)=0.53; P =0.002], cardiac complications (OR=0.69; P =0.012), sepsis (OR=0.69; P =0.035), renal complications (OR=0.54; P =0.044), and 90-day readmissions (OR=0.53; P =0.015).

CONCLUSIONS

Surgery-induced weight loss before an ACDF in obese patients is associated with reduced 90-day complication and readmission rates. Orthopaedic and bariatric surgeons should counsel obese patients on the benefits of BS following ACDFs.

Recognizing postoperative nutritional complications of bariatric surgery in the primary care patient: a narrative review

Bariatric surgery is an effective treatment for patients with morbid obesity. However, as safe and common as bariatric procedures have become, multiple complications can still result. These complications vary depending on the type of procedure performed (malabsorptive or restrictive) and are often nutritional derangements from the altered malabsorptive surface of the gastrointestinal tract and decreased capacity of the stomach. Deficiencies in vitamin D after malabsorptive procedures such as the Roux-en-Y gastric bypass can result in subsequent hypocalcemia and bone demineralization, and anemias can also present after surgery from inadequate vitamin B12 and iron absorption. Because of the prevalence of these deficiencies, baseline micronutrient testing and postoperative screening are recommended in many cases. Additionally, supplemental treatment often requires higher doses than those recommended for healthy adults. The purpose of this narrative review is to outline the various nutrient deficiencies that can result from bariatric procedures and report previously-published recommendations for screening and medical treatment of patients with these deficiencies. This review is directed toward primary care practitioners because of their unique position in delivering continuity of care and the frequency with which they will encounter patients who have undergone bariatric surgery and are seeking counseling regarding weight loss modalities.

IS THERE ANY CHANGE IN PHENOTYPIC CHARACTERISTICS COMPARING 5 TO 10 YEARS OF FOLLOW-UP IN OBESE PATIENTS UNDERGOING ROUX-EN-Y GASTRIC BYPASS?

Background

: Bariatric surgery promotes significant weight loss and improvement of associated comorbidities; however, nutrients deficiencies and weight regain may occur in the middle-late postoperative period.

Aim:

To investigate nutritional status in 10 years follow-up.

Methods

: Longitudinal retrospective study in which anthropometric, biochemical indicators and nutritional intake were assessed before and after one, two, three, four, five and ten years of Roux-en Y gastric bypass through analysis of medical records.

Results

: After ten years there was a reduction of 29.2% of initial weight; however, 87.1% of patients had significant weight regain. Moreover, there was an increase of incidence of iron (9.2% to 18.5%), vitamin B12 (4.2% to 11.1%) and magnesium deficiency (14.1% to 14.8%). Folic acid concentrations increased and the percentage of individuals with glucose (40.4% to 3.7%), triglycerides (38% to 7.4%), HDL cholesterol (31 % to 7.4%) and uric acid (70.5% to 11.1%) abnormalities reduced. Also, there is a reduction of food intake at first year postoperative. After 10 years, there was an increase in energy, protein and lipid intake, also a reduction in folid acid intake.

Conclusions

: Roux-en Y gastric bypass is an effective procedure to promote weight loss and improve comorbidities associated with obesity. However, comparison between postoperative period of five and 10 years showed a high prevalence of minerals deficiency and a significant weight regain, evidencing the need for nutritional follow-up in the postoperative period.

The history of metabolic and bariatric surgery: Development of standards for patient safety and efficacy

Weight loss surgery, also referred to as bariatric surgery, has been in existence since the 1950's. Over the decades, it has been demonstrated to successfully achieve meaningful and sustainable weight loss in a large number of patients who undergo these procedures. Additionally, the benefits observed across a number of metabolic disorders such as type 2 diabetes mellitus and hyperlipidemia, are often to a degree, independent of the weight loss, thus the term "metabolic bariatric surgery (MBS)" has become a better descriptor. Throughout its long history, MBS has evolved from an era of high morbidity and mortality to one of laudable safety despite the high-risk nature of the patients undergoing these major gastrointestinal procedures. This article will describe the historic evolution of MBS and concentrate on those events that were instrumental in reducing the morbidity of these operations.

The effectiveness and risks of bariatric surgery: an updated systematic review and meta-analysis, 2003-2012

IMPORTANCE

The prevalence of obesity and outcomes of bariatric surgery are well established. However, analyses of the surgery impact have not been updated and comprehensively investigated since 2003.

OBJECTIVE

To examine the effectiveness and risks of bariatric surgery using up-to-date, comprehensive data and appropriate meta-analytic techniques.

DATA SOURCES

Literature searches of Medline, Embase, Scopus, Current Contents, Cochrane Library, and Clinicaltrials.gov between 2003 and 2012 were performed.

STUDY SELECTION

Exclusion criteria included publication of abstracts only, case reports, letters, comments, or reviews; animal studies; languages other than English; duplicate studies; no surgical intervention; and no population of interest. Inclusion criteria were a report of surgical procedure performed and at least 1 outcome of interest resulting from the studied surgery was reported: comorbidities, mortality, complications, reoperations, or weight loss. Of the 25,060 initially identified articles, 24,023 studies met the exclusion criteria, and 259 met the inclusion criteria.

DATA EXTRACTION AND SYNTHESIS

A review protocol was followed throughout. Three reviewers independently reviewed studies, abstracted data, and resolved disagreements by consensus. Studies were evaluated for quality.

MAIN OUTCOMES AND MEASURES

Mortality, complications, reoperations, weight loss, and remission of obesity-related diseases.

RESULTS

A total of 164 studies were included (37 randomized clinical trials and 127 observational studies). Analyses included 161,756 patients with a mean age of 44.56 years and body mass index of 45.62. We conducted random-effects and fixed-effect meta-analyses and meta-regression. In randomized clinical trials, the mortality rate within 30 days was 0.08% (95% CI, 0.01%-0.24%); the mortality rate after 30 days was 0.31% (95% CI, 0.01%-0.75%). Body mass index loss at 5 years postsurgery was 12 to 17. The complication rate was 17% (95% CI, 11%-23%), and the reoperation rate was 7% (95% CI, 3%-12%). Gastric bypass was more effective in weight loss but associated with more complications. Adjustable gastric banding had lower mortality and complication rates; yet, the reoperation rate was higher and weight loss was less substantial than gastric bypass. Sleeve gastrectomy appeared to be more effective in weight loss than adjustable gastric banding and comparable with gastric bypass.

CONCLUSIONS AND RELEVANCE

Bariatric surgery provides substantial and sustained effects on weight loss and ameliorates obesity-attributable comorbidities in the majority of bariatric patients, although risks of complication, reoperation, and death exist. Death rates were lower than those reported in previous meta-analyses.

The effectiveness and risks of bariatric surgery: an updated systematic review and meta-analysis, 2003-2012

IMPORTANCE

The prevalence of obesity and outcomes of bariatric surgery are well established. However, analyses of the surgery impact have not been updated and comprehensively investigated since 2003.

OBJECTIVE

To examine the effectiveness and risks of bariatric surgery using up-to-date, comprehensive data and appropriate meta-analytic techniques.

DATA SOURCES

Literature searches of Medline, Embase, Scopus, Current Contents, Cochrane Library, and Clinicaltrials.gov between 2003 and 2012 were performed.

STUDY SELECTION

Exclusion criteria included publication of abstracts only, case reports, letters, comments, or reviews; animal studies; languages other than English; duplicate studies; no surgical intervention; and no population of interest. Inclusion criteria were a report of surgical procedure performed and at least 1 outcome of interest resulting from the studied surgery was reported: comorbidities, mortality, complications, reoperations, or weight loss. Of the 25,060 initially identified articles, 24,023 studies met the exclusion criteria, and 259 met the inclusion criteria.

DATA EXTRACTION AND SYNTHESIS

A review protocol was followed throughout. Three reviewers independently reviewed studies, abstracted data, and resolved disagreements by consensus. Studies were evaluated for quality.

MAIN OUTCOMES AND MEASURES

Mortality, complications, reoperations, weight loss, and remission of obesity-related diseases.

RESULTS

A total of 164 studies were included (37 randomized clinical trials and 127 observational studies). Analyses included 161,756 patients with a mean age of 44.56 years and body mass index of 45.62. We conducted random-effects and fixed-effect meta-analyses and meta-regression. In randomized clinical trials, the mortality rate within 30 days was 0.08% (95% CI, 0.01%-0.24%); the mortality rate after 30 days was 0.31% (95% CI, 0.01%-0.75%). Body mass index loss at 5 years postsurgery was 12 to 17. The complication rate was 17% (95% CI, 11%-23%), and the reoperation rate was 7% (95% CI, 3%-12%). Gastric bypass was more effective in weight loss but associated with more complications. Adjustable gastric banding had lower mortality and complication rates; yet, the reoperation rate was higher and weight loss was less substantial than gastric bypass. Sleeve gastrectomy appeared to be more effective in weight loss than adjustable gastric banding and comparable with gastric bypass.

CONCLUSIONS AND RELEVANCE

Bariatric surgery provides substantial and sustained effects on weight loss and ameliorates obesity-attributable comorbidities in the majority of bariatric patients, although risks of complication, reoperation, and death exist. Death rates were lower than those reported in previous meta-analyses.

[Metabolic effects of bariatric surgery]

Bariatric surgery managing/preventing complications of severe overweight is nowadays widely accepted as a mainstay in the treatment of morbid obesity. Its role is particularly important in type 2 diabetes developing on the base of long-standing significant overweight. The glycemic control improves within days-weeks after these surgeries, when weight loss and reduction of the visceral fat mass is barely detectable. This short term effect is probably due to an increased secretion of glucagon-like peptide and, as a consequence, an improvement in hepatic insulin sensitivity as well as the whole body glucose uptake. Besides the prolonged glucagon-like peptide effects, the favourable long term effect of these operations - lasting for 10 years even after surgery - is the decrease of visceral fat mass and elimination of harmful influence of cytokines produced by the fatty tissue. The article overviews the metabolic effects of these procedures, their undoubted advantages and potential risks.

Pharmacokinetic considerations in Roux-en-Y gastric bypass patients

PURPOSE

Pharmacokinetic considerations in patients who have undergone Roux-en-Y gastric bypass (RYGB) are explored.

SUMMARY

The prevalence of obesity, especially morbid obesity, has dramatically increased in recent years. In response, the number of bariatric surgeries performed has risen sharply, as this surgery is the technique demonstrated as being the most effective for sustained treatment of morbid obesity. RYGB, the most popular technique in the United States, combines the principle of restriction (dramatically decreasing stomach size) with malabsorption (bypassing the entire duodenum). It stands to reason that a decrease in gastric and intestinal absorptive surface area may considerably affect oral bioavailability of some drugs. Drugs that require a more acidic environment for absorption, uncoating, or activation and drugs that rely on intestinal transporters located in the duodenum for proper absorption would be most affected. Practitioners looking for guidance in tailoring pharmacotherapy to the RYGB patient will find little help in the primary literature at this time. Until more pharmacokinetic studies are available, practitioners may apply and log P of individual the principles of pK(a) drugs in the attempt to predict the potential impact of the RYGB on a drug's absorption. Likewise, if a drug relies on certain transporters located with highest frequency in the duodenum, alternative therapies can be selected that do not rely on such transport mechanisms for absorption.

CONCLUSION

The pK(a), log P, and intestinal transport mechanisms should be considered when determining which drugs may have altered pharmacokinetics in patients who have undergone RYGB.