Risedronate use to attenuate bone loss following sleeve gastrectomy: Results from a pilot randomized controlled trial

Bone health in adults with obesity before and after interventions to promote weight loss

Obesity and its associated comorbidities constitute a serious and growing public health burden. Fractures affect a substantial proportion of people with obesity and result from reduced bone strength relative to increased mechanical loading, together with an increased risk of falls. Factors contributing to fractures in people with obesity include adverse effects of adipose tissue on bone and muscle and, in many people, the coexistence of type 2 diabetes. Strategies to reduce weight include calorie-restricted diets, exercise, bariatric surgery, and pharmacological interventions with GLP-1 receptor agonists. However, although weight loss in people with obesity has many health benefits, it can also have adverse skeletal effects, with increased bone loss and fracture risk. Priorities for future research include the development of effective approaches to reduce fracture risk in people with obesity and the investigation of the effects of GLP-1 receptor agonists on bone loss resulting from weight reduction.

Obesity and Skeletal Fragility

Skeletal fracture has recently emerged as a complication of obesity. Given the normal or better than normal bone mineral density (BMD), the skeletal fragility of these patients appears to be a problem of bone quality rather than quantity. Type 2 diabetes mellitus (T2DM), the incidence of which increases with increasing body mass index, is also associated with an increased risk for fractures despite a normal or high BMD. With the additional bone pathology from diabetes itself, patients with both obesity and T2DM could have a worse skeletal profile. Clinically, however, there are no available methods for identifying those who are at higher risk for fractures or preventing fractures in this subgroup of patients. Weight loss, which is the cornerstone in the management of obesity (with or without T2DM), is also associated with an increased risk of bone loss. This review of the literature will focus on the skeletal manifestations associated with obesity, its interrelationship with the bone defects associated with T2DM, and the available approach to the bone health of patients suffering from obesity.

Strategies to reduce the onset of sleeve gastrectomy associated bone loss (STRONG BONES): Trial design and methods

Background

Despite recognized improvements in obesity-related comorbidities, mounting evidence implicates surgical weight loss in the onset of skeletal fragility. Sleeve gastrectomy (SG) is the most commonly performed bariatric procedure and is associated with 3-7% axial bone loss in the year following surgery. Bisphosphonates are FDA-approved medications for the prevention and treatment of age-related bone loss and may represent a strategy to reduce bone loss following SG surgery.

Methods

The Strategies to Reduce the Onset of Sleeve Gastrectomy Associated Bone Loss (STRONG BONES) trial (NCT04922333) is designed to definitively test whether monthly administration of the bisphosphonate, risedronate, for six months can effectively counter SG-associated bone loss. Approximately 120 middle-aged and older (≥40 years) SG patients will be randomized to six months of risedronate or placebo treatment, with skeletal outcomes assessed at baseline, six, and 12-months post-surgery. The primary outcome of the trial is 12-month change in total hip areal bone mineral density (aBMD), measured by dual energy x-ray absorptiometry (DXA). This will be complemented by DXA-acquired aBMD assessment at other skeletal sites and quantitative computed tomography (QCT) derived changes in bone quality. Change in muscle mass and function will also be assessed, as well as biomarkers of bone health, turnover, and crosstalk, providing mechanistic insight into intervention-related changes to the bone-muscle unit.

Discussion

Results from the STRONG BONES trial have the potential to influence current clinical practice by determining the ability of bisphosphonate use to mitigate bone loss and concomitant fracture risk in middle-aged and older SG patients.

Risedronate use may blunt appendicular lean mass loss secondary to sleeve gastrectomy: Results from a pilot randomized controlled trial

Background

Despite robust weight loss and cardiometabolic benefit, lean mass loss following sleeve gastrectomy (SG) confers health risk. Bisphosphonates are a potential therapeutic agent for lean mass maintenance. Thus, our objective was to explore the effect of six months of risedronate (vs placebo) on change in dual energy x-ray absorptiometry (DXA) and computed tomography (CT) derived lean mass metrics in the year following SG.

Methods

24 SG patients were randomized to six months of 150 mg oral risedronate or placebo capsules (NCT03411902). Body composition was assessed at baseline and six months with optional 12-month follow-up using whole-body DXA and CT at the lumbar spine and mid-thigh. Group treatment effects and 95% CIs were generated from a mixed model using contrast statements at six and 12 months, adjusted for baseline values.

Results

Of 24 participants enrolled [55.7±6.7 years (mean±SD), 79% Caucasian, 83% women, body mass index (BMI) 44.7±6.3kg/m2], 21 returned for six-month testing, and 14 returned for 12-month testing. Six-month weight loss was -16.3 kg (-20.0, -12.5) and -20.9 kg (-23.7, -18.1) in the risedronate and placebo groups, respectively (p=.057). Primary analysis at six-months revealed a non-significant sparing of appendicular lean mass in the risedronate group compared to placebo [-1.2 kg (-2.3, -0.1) vs -2.1 kg (-3.0, -1.2)]; p=.20. By 12-months, the risedronate group displayed no change in appendicular lean mass from baseline [-0.5 kg (-1.5, 0.6)]; however, the placebo group experienced significantly augmented loss [-2.9 kg (-3.6, -2.1)].

Conclusion

Pilot data indicate risedronate treatment may mitigate appendicular lean mass loss following SG. Further study is warranted.

The Effect of Exercise for the Prevention of Bone Mass After Bariatric Surgery: a Systematic Review and Meta-analysis

We aimed to assess if exercise applied after bariatric surgery (BS) improves bone mineral density (BMD) compared to usual care. Systematic search was conducted up to January 2021. Effect measures were determined using standardized mean difference (SMD) with 95% confidence interval (CI). Certainty evidence was assessed according to GRADE. Four clinical trials encompassing 340 patients were included. Exercise induced a positive BMD effect at total hip (SMD = 0.37 [95% CI 0.02, 0.71]; very low certainty evidence), femoral neck (SMD = 0.63 [95% CI 0.19, 1.06]; low certainty evidence), lumbar spine (SMD = 0.41 [95% CI 0.19, 0.62]; low certainty evidence), and 1/3 radius (SMD = 0.58 [95% CI 0.19, 0.97]; low certainty evidence). Exercise undertaken after BS seems to induce a positive effect on BMD.

Protocol for a pilot randomised controlled trial of zoledronic acid to prevent bone loss following sleeve gastrectomy surgery

INTRODUCTION

Sleeve gastrectomy (SG) is an increasingly used and effective treatment for obesity; however, the rapid weight loss associated with SG adversely affects bone metabolism predisposing patients to skeletal fragility. Bisphosphonate medications have been evaluated for safety and efficacy in combating bone loss in patients with osteoporosis, but their use in SG-induced bone loss is limited. The goal of this study is to investigate how a one-time infusion of zoledronic acid compares to placebo, in its ability to combat SG-associated bone loss.

METHODS AND ANALYSIS

This research protocol is a 9-month, pilot randomized controlled trial (RCT) involving 30 adult SG patients randomised to receive an infusion of either 5 mg of zoledronic acid or placebo, 6 weeks following surgery. To be included participants must be <350 lbs/158.8 kg, free of bone-impacting pathologies or medications, and must have adequate serum calcium and vitamin D levels at baseline. The primary outcome is change in areal bone mineral density (aBMD) at the total hip. Secondary outcomes include change in aBMD of the femoral neck, and lumbar spine, and change in volumetric BMD at the lumbar spine. The primary aim will be tested using a linear mixed model fit with total hip aBMD at 9 months as the outcome. Treatment, participant sex and menopausal status will be considered in analysis. Groups will be compared using contrast statements at 9 months, with change over 9 months being the primary comparison.

ETHICS AND DISSEMINATION

This study was approved by the Institutional Review Board of the University of Nebraska Medical Center (IRB820-19). Written consent will be obtained from participants at enrolment by trained staff. Careful and thorough explanation are used in obtainment of consent and voluntariness is emphasised throughout the trial. The findings of this study will be presented locally, nationally, and published in peer-reviewed journals. Additional details will be reported on ClinicalTrials.gov.

TRIAL REGISTRATION NUMBER

NCT04279392.