Skeletal Effects of Sleeve Gastrectomy in Adolescents and Young Adults: A 2-Year Longitudinal Study

Bone mineral density in young adults 5 to 11 years after adolescent metabolic and bariatric surgery for severe obesity compared to peers

OBJECTIVE

Metabolic and bariatric surgery (MBS) is associated with decreased bone mineral density (BMD) in adults. The long-term impact of MBS during adolescence on BMD is unknown. We report bone health status 5 to 11 years after Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) from the Teen-LABS study cohort.

METHODS

Between 2016 and 2022, BMD was measured by dual energy x-ray absorptiometry (DXA) in 106 young adults who had undergone MBS as adolescents. Volumetric BMD by peripheral quantitative computed tomography was measured on a subset. Ninety-one controls who had not undergone MBS were recruited for comparison.

RESULTS

In cases (RYGB: mean age 26.8 ± 1.9 years, mean BMI 42.1 ± 9.9 kg/m2, VSG: mean age 25.1 ± 2.1 years, mean BMI 37.1 ± 8.4 kg/m2), compared to controls (mean age 26.5 ± 2.7 years, mean BMI 40.2 ± 8.7 kg/m2) (age p < 0.001, BMI p = 0.02), adjusted mean DXA-BMD (g/cm2) of the RYGB (n = 58) and VSG (n = 48) groups were lower at the hip (-10.0% and -6.3%), femoral neck (-9.6% and -5.7%) and ultra-distal radius (-7.9% and -7.0%; all p < 0.001), respectively. DXA-BMD did not differ between RYGB and VSG groups. Trabecular volumetric BMD at the radius and tibia were lower in the RYGB (-30% and -26%) and VSG (-15% and -14%) groups compared to the control group (p < 0.001). Greater time since MBS was associated with lower BMD Z-scores at the hip (p = 0.05) and femoral neck (p = 0.045). Percent change in body mass index (BMI) from baseline or in the first year after MBS were not associated with bone measures at a median of 9.3 years post MBS.

CONCLUSION

BMD, especially of the hip and femoral neck, was lower in young adults who underwent MBS during adolescence compared to matched peers who had not undergone MBS. BMD Z-scores of the femoral neck were inversely associated with time since MBS but were not associated with BMI change.

Bone health following paediatric and adolescent bariatric surgery: a systematic review and meta-analysis

Background

Childhood obesity is a pressing health crisis of epidemic proportions. Bariatric surgery (BS) is an effective weight loss solution however its role in the paediatric population is contentious owing to the paucity of weight specific and generalised health outcomes. This systematic review and meta-analysis aimed to assess the impact of paediatric BS on bone health.

Methods

This prospectively registered systematic review (PROSPERO ID: CRD42023432035) was performed in accordance with PRISMA guidelines. We searched MEDLINE (1946-1928 September 2023), EMBASE (1947-1928 September 2023) via the Ovid platform, and the Cochrane Review Library to identify scientific publications reporting bone outcome measures in patients under the age of 18 years who underwent BS. Meta-analysis was undertaken on post-operative weight and bone parameters in paediatric patients following BS. Outcomes were reported as weighted or standardized mean difference with 95 percent confidence intervals. Subgroup analysis by intervention, quality scoring and risk of bias were assessed.

Findings

Twelve studies with 681 patients across 5 countries (mean age 17 ± 0.57 years) were included. The quality of included studies was rated as high and there was substantial between-study heterogeneity for most factors included in the meta-analysis (I2 from 0% to 99.1%). Patients underwent Roux-en-Y gastric bypass (RYGB, n = 216), sleeve gastrectomy (SG, n = 257), gastric band (n = 184) or intragastric balloon placement (n = 24). BS was associated with significant weight reduction, body mass index (BMI) -12.7 kg/m2 (95% CI -14.5 to -10.9, p < 0.001), with RYGB being most effective, BMI -16.58 kg/m2 (95% CI -19.6 to -13.6, p < 0.001). Patients who underwent SG or RYGB had significantly lower lumbar bone mineral density, -0.96 g/cm2 (95% CI -0.1 to -0.03, p < 0.001), Z score, -1.132 (95% CI -1.8 to -0.45, p < 0.001) and subtotal body bone mineral density, -0.7 g/cm2 (95% CI -1.2 to -0.2, p < 0.001) following surgery. This was accompanied with higher markers of bone resorption, C-terminal telopeptide of type 1 collagen 0.22 ng/ml (95% CI 0.12-0.32, p < 0.001) and osteocalcin, 10.83 ng/ml (95% CI 6.01-15.67, p < 0.001). There was a significant reduction in calcium levels following BS, -3.78 mg/dl (95% CI -6.1 to -1.5, p < 0.001) but no difference in 25-hydroxyvitamin D, phosphate, bone alkaline phosphatase, procollagen type 1 N propeptide or parathyroid hormone.

Interpretation

BS effectively reduces weight in paediatric patients, but RYGB and SG may have adverse effects on bone health in the medium term. It is crucial to monitor and support bone health through appropriate nutritional supplementation and judicious follow-up. Long-term data is needed to fully understand the clinical implications of these findings on bone outcomes.

Funding

Medical Research Council (MRC), United Kingdom.

Risk of wrist fracture, estimated by the load-to-strength ratio, declines following sleeve gastrectomy in adolescents and young adults

To understand whether the bone loss which occurs after vertical sleeve gastrectomy increases the risk of fracture, we used an engineering model to estimate risk in participants before and after surgery. We found that estimated risk decreased 1 year after surgery and remained lower, though had rebounded, at year 2.

PURPOSE

Vertical sleeve gastrectomy (VSG) improves metabolic health in young people with obesity but is accompanied by substantial loss of bone mass and estimated bone strength. We thus estimated fracture risk following VSG using the load-to-strength ratio (LSR), which integrates bone strength estimates with the predicted force of a fall.

METHODS

Prospective 2-year study of youth ages 13-24 years with obesity undergoing VSG (n = 24) or lifestyle therapy (n = 34). We performed high-resolution peripheral quantitative computed tomography of the distal radius and microfinite element analysis to estimate bone strength and calculated LSR.

RESULTS

VSG participants lost 26.4 ± 8.1% weight at year 1 (p < 0.001), which was sustained at year 2, while control participants gained weight at year 2 (4.5 ± 8.3%, p = 0.009). The predicted impact force decreased at years 1 and 2 following VSG (p < 0.001) but increased at year 2 among controls (p = 0.011). Estimated bone strength was unchanged at year 1 but decreased (p < 0.001) at year 2 following VSG, while bone strength did not change in controls. At year 1, the LSR decreased among VSG participants (p < 0.001), implying a lower risk of fracture. At year 2, the LSR was lower than baseline (p < 0.001), but higher compared to year 1 (p = 0.001). LSR did not change in the control group.

CONCLUSIONS

Short-term estimated fracture risk at the radius following VSG decreases. However, ongoing bone loss despite stable weight between years 1 and 2 leads to a concerning rise in estimated fracture risk. Longer follow-up will be critical to evaluate the trajectory of fracture risk. (ClinicalTrials.gov NCT02557438, registered 9/23/2015).

Bone mineral density 5 to 11 years after metabolic and bariatric surgery in adolescents with severe obesity compared to peers

Objective

Metabolic and bariatric surgery (MBS) is associated with decreased bone mineral density (BMD) in adults. The long-term impact of MBS during adolescence on BMD is unknown. We report bone health status 5 to 11 years after Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG) from the Teen-LABS study cohort.

Methods

Between 2016 and 2022, BMD was measured by dual energy x-ray absorptiometry (DXA) in 106 young adults who had undergone MBS as adolescents. Volumetric BMD by peripheral quantitative computed tomography was measured on a subset. Ninety-one controls who had not undergone MBS were recruited for comparison.

Results

Compared to controls, adjusted mean DXA-BMD of the RYGB (n = 58) and VSG (n = 48) groups were lower at the hip (-10.0% and - 6.3%), femoral neck (-9.6% and - 5.7%) and ultra-distal radius (-7.9% and - 7.0%; all p < 0.001), respectively. DXA-BMD did not differ between RYGB and VSG groups. Trabecular volumetric BMD at the radius and tibia were lower in the RYGB (-30% and - 26%) and VSG (-15% and - 14%) groups compared to the control group (p < 0.001). Greater time since MBS was associated with lower BMD Z-scores at the hip (p = 0.05) and femoral neck (p = 0.045). Percent change in body mass index (BMI) from baseline or in the first year after MSB were not associated with bone measures at a median of 9.3 years post MSB.

Conclusion

BMD, especially of the hip and femoral neck, was lower in young adults who underwent MBS during adolescence compared to matched peers who had not undergone MBS. BMD Z-scores of the femoral neck decreased with time since MBS but were not associated with BMI change.

Bone changes post-sleeve gastrectomy in relation to body mass and hormonal changes

OBJECTIVE

To determine mechanisms contributing to impaired bone health in youth 24 months following sleeve gastrectomy (SG).

DESIGN

Twenty-four-month longitudinal observational study.

METHODS

Participants included 23 youth undergoing SG and 30 non-surgical controls (NS) 13-25 years old with moderate-to-severe obesity. Subjects underwent fasting labs for bone turnover markers (N-terminal propeptide of type 1 procollagen, C-telopeptide (CTX)), sex hormones, sex hormone binding globulin (SHBG), and enteric peptides, DXA for areal bone mineral density (aBMD) and body composition, high-resolution peripheral quantitative CT for volumetric BMD (vBMD) at the distal radius and tibia, and microfinite element analysis for strength estimates.

RESULTS

Groups did not differ for mean age or BMI z-scores. Over 24 months, compared to NS, SG had greater reductions in BMI z-scores, and spine, hip, and femoral neck aBMD Z-scores (P ≤ .012), greater increases in serum CTX and SHBG (P ≤ .039), and greater decreases in estrone and ghrelin (P ≤ .021). Among females, estrone and free androgen index (FAI) decreased (P ≤ .022) in SG vs NS groups. After controlling for age and sex, decreases in BMI and lean mass were associated with decreases in total hip and femoral neck aBMD Z-scores, and decreases in radial total and trabecular vBMD and failure load, and tibial total and trabecular vBMD. Among females, after controlling for age, decreases in estrone were associated with decreases in spine aBMD Z-scores and radial total and trabecular vBMD, and decrease in FAI with decreases in radial failure load.

CONCLUSION

Reductions in BMI, lean mass, and sex steroids over 24 months post-SG are associated with bone loss and could be targeted for preventative or therapeutic interventions. Clinical trial registration number: The study is registered in ClinicalTrials.gov (NCT02557438).

Long-term Outcomes Following Adolescent Metabolic and Bariatric Surgery

Severe obesity in adolescence negatively impacts upon health and wellbeing. Lifestyle modifications do not usually achieve a sufficient degree or durability of weight loss to mitigate the risk of medical complications. In recent years, metabolic and bariatric surgery (MBS), already a well-established treatment for adults with severe obesity, has emerged as an option in adolescents. Controlled studies in this age group have demonstrated substantial and sustained weight loss, improvements in associated health parameters, and a safety profile surpassing that observed in adult patients. This review aims to present published data on the results of MBS in adolescents with a focus on long-term outcomes. Indications for bariatric surgery and aspects of timing in the young person's life are also presented, along with safety considerations and factors influencing patient selection for surgery. We conclude, predominantly from short- to medium-term outcomes data, that MBS is a safe and valuable therapeutic option for adolescents with severe obesity. Considering the poor health and social wellbeing prognosis in this group, MBS appears to be underutilized. The need for continued research, multiprofessional specialist provision, coherent contemporary clinical guidelines, and routine long-term follow-up in adolescents undergoing MBS is highlighted.

Serum Oxytocin Levels Decrease 12 Months Following Sleeve Gastrectomy and Are Associated with Decreases in Lean Mass

Oxytocin (OXT), an anorexigenic hormone, is also bone anabolic. Further, OXT administration results in increases in lean mass (LM) in adults with sarcopenic obesity. We examine, for the first time, associations of OXT with body composition and bone endpoints in 25 youth 13-25 years old with severe obesity who underwent sleeve gastrectomy (SG) and 27 non-surgical controls (NS). Forty participants were female. Subjects underwent fasting blood tests for serum OXT and DXA for areal bone mineral density (aBMD) and body composition. At baseline, SG vs. NS had higher median body mass index (BMI) but did not differ for age or OXT levels. Over 12 months, SG vs. NS had greater reductions in BMI, LM, and fat mass (FM). OXT decreased in SG vs. NS 12 months post-SG. While baseline OXT predicted a 12-month BMI change in SG, decreases in OXT levels 12 months post-SG were not associated with decreases in weight or BMI. In SG, decreases in OXT were positively associated with decreases in LM but not with decreases in FM or aBMD. Loss of LM, a strong predictor of BMD, after bariatric surgery may reduce functional and muscular capacity. OXT pathways may be targeted to prevent LM loss following SG.