A meta-analysis of the effects of bariatric surgery on fracture risk

Relationship Between Metabolic Syndrome and Bone Health - An Evaluation of Epidemiological Studies and Mechanisms Involved

Metabolic syndrome (MetS) and osteoporosis are two medical problems plaguing the ageing populations worldwide. Though seemingly distinctive to each other, metabolic derangements are shown to influence bone health. This review summarises the relationship between MetS and bone health derived from epidemiological studies and explains the mechanistic basis of this relationship. The discourse focuses on the link between MetS and bone mineral density, quantitative sonometric indices, geometry and fracture risk in humans. The interesting sex-specific trend in the relationship, probably due to factors related to body composition and hormonal status, is discussed. Mechanistically, each component of MetS affects the bone distinctly, forming a complex interacting network influencing the skeleton. Lastly, the effects of MetS management, such as pharmacotherapies, exercise and bariatric surgery, on bone, are presented. This review aims to highlight the significant relationship between MetS and bone, and proper management of MetS with the skeletal system in mind could prevent cardiovascular and bone complications.

A place for vitamin supplementation and functional food in bariatric surgery?

PURPOSE OF REVIEW

This article summarizes recent literature concerning vitamin deficiency and required supplementation post-bariatric surgery, focusing on vitamin D (and associated clinical adverse effect on bone loss) and on the potential implication of the gut microbiota.

RECENT FINDINGS

Bariatric surgery induces weight loss and metabolic improvements yet with major inter-individual variability. If it is efficient in most patients, some display poor response (i.e. patients with the lowest weight loss at 1 year or weight regain afterwards, or patients without metabolic disease remission). Despite systematic vitamin supplementation, some patients develop vitamin deficiencies leading to poor clinical outcomes, among which vitamin D deficiency associated with observed bone mass loss and fractures. Recent mechanistic studies led to understand better the involved physiopathology. Furthermore, different intervention studies tested on top of bariatric surgery (using vitamin, diet, or nutrients acting as functional food) have evaluated whether nutritional adverse outcomes could be improved. Importantly, gut microbiota involved in food digestion and metabolization and vitamin synthesis is largely perturbed during severe obesity and is partially restored post-surgery, yet again with large interindividual variability. Whether differential gut microbiota modification could be associated with vitamin deficiencies is an open question.

SUMMARY

Future clinical research studies will need to evaluate whether add-on intervention to bariatric surgery using vitamin, diet, or specific food items could help prevent nutritional deficiencies and improve clinical response observed post-surgery. Importantly, personalizing the add-on intervention post-surgery upon gut microbiota composition should be tested in predicted poor-responders to surgery as already performed during diet intervention to further improve metabolic health.

Two-Year Nutrition Data in Terms of Vitamin D, Vitamin B12, and Albumin After Bariatric Surgery and Long-term Fracture Data Compared with Conservatively Treated Obese Patients: a Retrospective Cohort Study

INTRODUCTION

Nutritional deficiencies may occur after bariatric surgery despite supplementation. Fracture risk may also be elevated after bariatric surgery.

OBJECTIVES

To compare 25-hydroxyvitamin D [25(OH)D], vitamin B12, and albumin serum concentrations in severely obese patients who had undergone either Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG). Fracture data was compared with data for a conservatively treated group of severely obese patients.

METHODS

We considered 253 RYGB and 142 SG performed between 2007 and 2010. At 1- and 2-year control follow-ups, weight was measured and blood samples were drawn. The control group of 199 obese patients received lifestyle intervention and weight was measured at 1 and 2 years post-intervention between 2002 and 2006. We retrospectively collected fracture data for all patients through the end of 2016.

RESULTS

At follow-ups, the mean serum 25(OH)D and albumin levels were within reference ranges and were similar between the RYGB and SG groups. Serum median vitamin B12 level was significantly higher in the SG group compared with the RYBG group, 319 versus 286 pmol/L at 2 years, respectively, p = 0.04. The cumulative risk for fracture was higher in the bariatric groups compared with the control group. The Cox multivariate model showed higher age, bariatric surgery, and lower body mass index (BMI) at the 2-year control increased the risk for fracture after obesity treatment.

CONCLUSION

Vitamin 25(OH)D, B12, and albumin levels were mainly within recommended levels during the 2 years after bariatric surgery. The cumulative fracture risk was higher in bariatric patients.

Obesity, Bariatric Surgery, and Fractures

CONTEXT

Obesity and its associated comorbidities are a recognized and growing public health problem. For a long time, obesity-associated effects on bone were considered to strengthen the bone, mainly because of the known relationship between body weight and bone mass and the long-term weight-bearing load effect on bone. However, recent epidemiologic studies have shown that obesity may not have a fully protective effect on the occurrence of fragility fractures. The goal of this article is to review updated information on the link between obesity, bariatric surgery, and fractures.

METHODS

The primary source literature for this review was acquired by searching a published database for reviews and articles up to January 2018. Additional references were selected through the in-depth analysis of the relevant studies.

RESULTS

We present data showing that overweight and obesity are often encountered in fracture cases. We also analyzed possible reasons and risk factors for fractures associated with overweight and patients with obesity. In addition, this review focuses on the complex effects of dramatic changes in body composition when interpreting dual-energy X-ray absorptiometry readings and findings. Finally, we review the data on the effects and consequences of bariatric surgery on bone metabolism and the risk of fractures in patients undergoing these procedures.

CONCLUSION

Because of various adiposity-induced effects, patients with obesity are at risk for fracture in certain sites. Bariatric surgery increases the risk of fractures in patients undergoing malabsorptive procedures.

Exercise Mitigates Bone Loss in Women With Severe Obesity After Roux-en-Y Gastric Bypass: A Randomized Controlled Trial

CONTEXT

Bone loss after bariatric surgery potentially could be mitigated by exercise.

OBJECTIVE

To investigate the role of exercise training (ET) in attenuating bariatric surgery-induced bone loss.

DESIGN

Randomized, controlled trial.

SETTING

Referral center for bariatric surgery.

PATIENTS

Seventy women with severe obesity, aged 25 to 55 years, who underwent Roux-en-Y gastric bypass (RYGB).

INTERVENTION

Supervised, 6-month, ET program after RYGB vs. standard of care (RYGB only).

OUTCOMES

Areal bone mineral density (aBMD) was the primary outcome. Bone microarchitecture, bone turnover, and biochemical markers were secondary outcomes.

RESULTS

Surgery significantly decreased femoral neck, total hip, distal radius, and whole body aBMD (P < 0.001); and increased bone turnover markers, including collagen type I C-telopeptide (CTX), procollagen type I N-propeptide (P1NP), sclerostin, and osteopontin (P < 0.05). Compared with RYGB only, exercise mitigated the percent loss of aBMD at femoral neck [estimated mean difference (EMD), -2.91%; P = 0.007;], total hip (EMD, -2.26%; P = 0.009), distal radius (EMD, -1.87%; P = 0.038), and cortical volumetric bone mineral density at distal radius (EMD, -2.09%; P = 0.024). Exercise also attenuated CTX (EMD, -0.20 ng/mL; P = 0.002), P1NP (EMD, -17.59 ng/mL; P = 0.024), and sclerostin levels (EMD, -610 pg/mL; P = 0.046) in comparison with RYGB. Exercise did not affect biochemical markers (e.g., 25(OH)D, calcium, intact PTH, phosphorus, and magnesium).

CONCLUSION

Exercise mitigated bariatric surgery-induced bone loss, possibly through mechanisms involving suppression in bone turnover and sclerostin. Exercise should be incorporated in postsurgery care to preserve bone mass.

G-CSF partially mediates effects of sleeve gastrectomy on the bone marrow niche

Bariatric surgeries are integral to the management of obesity and its metabolic complications. However, these surgeries cause bone loss and increase fracture risk through poorly understood mechanisms. In a mouse model, vertical sleeve gastrectomy (VSG) caused trabecular and cortical bone loss that was independent of sex, body weight, and diet, and this loss was characterized by impaired osteoid mineralization and bone formation. VSG had a profound effect on the bone marrow niche, with rapid loss of marrow adipose tissue, and expansion of myeloid cellularity, leading to increased circulating neutrophils. Following VSG, circulating granulocyte-colony stimulating factor (G-CSF) was increased in mice, and was transiently elevated in a longitudinal study of humans. Elevation of G-CSF was found to recapitulate many effects of VSG on bone and the marrow niche. In addition to stimulatory effects of G-CSF on myelopoiesis, endogenous G-CSF suppressed development of marrow adipocytes and hindered accrual of peak cortical and trabecular bone. Effects of VSG on induction of neutrophils and depletion of marrow adiposity were reduced in mice deficient for G-CSF; however, bone mass was not influenced. Although not a primary mechanism for bone loss with VSG, G-CSF plays an intermediary role for effects of VSG on the bone marrow niche.

Metabolic surgery for the treatment of type 2 diabetes in patients with BMI lower than 35 kg/m2 : Why caution is still needed

Bariatric surgery has shifted from being a risky procedure to an evidence-based one, with proven benefits on all-cause mortality, cardiovascular disease, cancer, and diabetes control. The procedure has an overall positive result on type 2 diabetes mellitus (T2DM), with a substantial number of patients achieving disease remission. This has resulted in several studies assessing possible weight-independent effects of bariatric surgery on glycemic improvement, in addition to recommendation of the procedure to patients with class 1 obesity and T2DM, for whom the procedure was classically not indicated, and adoption of a new term, "metabolic surgery," to highlight the overall metabolic benefit of the procedure beyond weight loss. Recently, the Diabetes Surgery Summit (DSS) has included metabolic surgery in its T2DM treatment algorithm. Although the discussion brought by this consensus is highly relevant, the recommendation of metabolic surgery for patients with uncontrolled T2DM and a body mass index of 30 to 35 kg/m² still lacks enough evidence. This article provides an overall view of the metabolic benefits of bariatric/metabolic surgery in patients with class 1 obesity, compares the procedure against clinical treatment, and presents our rationale for defending caution on recommending the procedure to less obese individuals.

Consequences of bariatric surgery on outcomes in rheumatic diseases

Obesity is associated with numerous comorbidities including some rheumatic conditions. Through adipose-derived inflammation, obesity has been shown to induce increased initiation, progression, and worse responses on outcomes of rheumatic diseases. Bariatric surgery is being increasingly used thanks to its positive effects on major comorbidities such as type 2 diabetes mellitus and hypertension. Consequently, surgically induced weight and adipose tissue losses might play a role in the course of rheumatic conditions. The present narrative literature review aims to provide rheumatologists with an update on both the positive and negative effects of bariatric surgery on the rheumatic outcomes reported in the literature. Current evidence seems to show improved outcomes in obese populations with rheumatic disorders after bariatric surgery. However, rigorous prospective controlled studies with long follow-up are needed. Bariatric procedures have deleterious effects on bone and are associated with an increased risk of fractures.

Vitamin D supplementation in obesity and during weight loss: A review of randomized controlled trials

Vitamin D deficiency is common in obese individuals and during weight loss. The recommended vitamin D doses in this specific population are higher than for healthy adults. We reviewed vitamin D supplementation trials in obesity, and during medical or surgical weight loss, and report the effects on 25-hydroxyvitamin D [25(OH)D] concentrations and other relevant outcomes. We conducted a systematic search in PubMed, Medline, Embase and the Cochrane library for relevant randomized controlled trials (RCTs) of oral vitamin D supplementation for at least 3 months in obese individuals without weight loss (OB), and those on medical weight loss (MWL) (2010-2018), and following bariatric surgery (Bar S) (without time restriction). Two reviewers screened the identified citations in duplicate and independently and performed full text screening. One reviewer completed data extraction. We identified 13 RCTs in OB, 6 in MWL and 7 in Bar S. Mean baseline 25(OH)D concentrations ranged between 7 and 27 ng/ml in OB, 15-29 ng/ml in MWL and 15-24 ng/ml in Bar S. In OB (Total N 2036 participants), vitamin D doses of 1600-4000 IU/d increased mean 25(OH)D concentrations to ≥30 ng/ml. Based on three trials during MWL (Total N 359 participants), vitamin D doses of 1200-4600 IU/d for 12 months increased 25(OH)D concentration to ≥30 ng/ml. In Bar S (Total N 615 participants), doses ≥2000 IU/d were needed to reach 30 ng/ml. The change in 25(OH)D concentration was inversely proportional to the administered dose, and to BMI and baseline level with doses of 600-3000 IU/day. With these doses, the change in 25(OH)D concentration [Δ25(OH)D] per 100 IU/d was 0.5-1.2 ng/ml. Three trials assessed bone mineral density as a primary outcome, but only one of them showed a protective effect of vitamin D against bone loss at all sites post-Bar S. There was no effect of vitamin D on weight loss. Data on extra-skeletal parameters, namely glycemic and vascular indices were mostly identified in OB, and findings were inconsistent. In conclusion, Vitamin D doses ≥1600-2000 IU/d may be needed to reach a 25(OH)D concentration of 30 ng/ml in obese individuals and following bariatric surgery. The optimal concentration in this population is unknown, and whether the above doses protect against weight loss induced bone loss and fractures still needs to be confirmed. There is no clear evidence for a beneficial effect of vitamin D supplementation on cardio-metabolic parameters in obese individuals, and data on such parameters with weight loss are very scarce. Well-designed long term RCTs assessing the effect of vitamin D supplementation during weight loss on patient important outcomes are needed.

Surgical management of obesity

Weight loss surgery is the most effective intervention for addressing obesity and related metabolic disorders such as diabetes. We describe common surgical procedures as well as emerging and investigational procedures in terms of their capacity to induce weight reduction and their risk profiles. We then discuss the impact of weight loss surgery on important obesity related disorders including diabetes, cardiovascular disease, and non-alcoholic fatty liver disease. The question of operative choice is discussed with respect to benefits and risks of common procedures. Reoperative weight loss surgery, an increasingly common element of weight loss surgical practice, is reviewed. We briefly discuss the metabolic mechanism of action of weight loss surgery. Lack of access to and under-utilization of weight loss surgery represent important challenges to adequate obesity treatment, and we review these topics as well.

Metabolic and Endocrine Consequences of Bariatric Surgery

Obesity is one of the most serious worldwide epidemics of the twenty-first century according to the World Health Organization. Frequently associated with a number of comorbidities, obesity threatens and compromises individual health and quality of life. Bariatric surgery (BS) has been demonstrated to be an effective treatment to achieve not only sustained weight loss but also significant metabolic improvement that goes beyond mere weight loss. The beneficial effects of BS on metabolic traits are so widely recognized that some authors have proposed BS as metabolic surgery that could be prescribed even for moderate obesity. However, most of the BS procedures imply malabsorption and/or gastric acid reduction which lead to nutrient deficiency and, consequently, further complications could be developed in the long term. In fact, BS not only affects metabolic homeostasis but also has pronounced effects on endocrine systems other than those exclusively involved in metabolic function. The somatotropic, corticotropic, and gonadal axes as well as bone health have also been shown to be affected by the various BS procedures. Accordingly, further consequences and complications of BS in the long term in systems other than metabolic system need to be addressed in large cohorts, taking into account each bariatric procedure before making generalized recommendations for BS. In this review, current data regarding these issues are summarized, paying special attention to the somatotropic, corticotropic, gonadal axes, and bone post-operative health.

Fertility, Pregnancy and Lactation After Bariatric Surgery - a Consensus Statement from the OEGGG

Bariatric surgery is recommended when other weight loss interventions, such as lifestyle modification or medications, have failed. A considerable number of women undergoing bariatric surgery are of childbearing age; hence, it is necessary to be aware of the effects of bariatric surgery on pregnancy for managing these patients. Although bariatric surgery is associated with positive effects on cardiovascular and metabolic parameters, side effects such as anaemia, the risk of developing internal hernia, altered glucose metabolism and the risk of small for gestational age offspring have to be considered. Pregnant women with a history of gastric bypass should not undergo the oral glucose tolerance test (OGTT) due to the high risk of hypoglycaemia. There are no contraindications for vaginal delivery and breastfeeding. This paper has been published as a consensus statement by the Austrian Society of Gynaecology and Obstetrics (OEGGG).

Long-term nutritional follow-up post bariatric surgery

PURPOSE OF REVIEW

Bariatric surgery is an effective treatment for classes II and III obesity and its associated diseases. However, many important long-term outcomes of bariatric surgery are still poorly understood, such as neurological and psychological complications, bone health, and so on. This review summarizes the current evidence and expert opinions on nutritional care in the long-term postoperative period.

RECENT FINDINGS

In the first section, we will provide an update of the main long-term complications: risk of anaemia, risk of bone fracture, neurological and psychological complications, and risk of developing Barrett's oesophagus after sleeve gastrectomy. We will also examine the current strategies used to increase weight loss or reduce weight regain. As adherence to long-term follow-up has been shown to decrease over time, the second section aims to identify all measures that improve follow-up rates, to get the maximum benefit from bariatric surgery, while minimizing long-term adverse effects and complications.

SUMMARY

There is still a significant level of uncertainty regarding the best clinical practices for maintaining the health benefits provided by bariatric surgery. The role of family physician in postsurgery care needs to be clearly defined. More effort is needed to improve psychological care, behaviour management, and therapeutic patient education after bariatric surgery. A more patient-centred approach should probably be considered.