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On April 24, 2023, we reported on a study published in the Journal of Bone and Mineral Research that examined the effect of sleeve gastrectomy (SG) on bone strength of the lumbar spine by biomechanical CT analysis in adolescents and young adults with severe obesity.
Inclusion criteria for participants were age 13 to 25 years; moderate-to-severe obesity (BMI ≥35 kg/m2) in adults; and BMI ≥120% of the 95th percentile for age and sex in adolescents.
Additional criteria to be considered for SG were an existing plan to undergo weight loss surgery, having a BMI of ≥35 kg/m2 and at least 1 obesity-related comorbidity, or a BMI ≥40 kg/m2. Exclusions were made for potential participants who were pregnant, had a history of medical disorders or use of medications known to affect bone metabolism, a history of smoking >10 cigarettes per day or of substance abuse per DSM-5, and body weight >200 kg.
Patients were evaluated at baseline, prior to surgery, and at 12 months post-surgery. Participants in the nonsurgical control arm also were examined at both points and received counseling on diet and exercise regimens to follow.
Also performed at baseline and follow-up visits were a helical CT of the lumbar spine (L1, L2) for analysis via biomechanical CT, and a single-slice MRI of the abdomen at the level of L4 and the mid-thigh for composition assessments at both visits. Effects of body composition on bone parameters were estimated using regression analysis and multivariable analyses were conducted to control for baseline and 12-month changes in BMI.
The final cohort enrolled numbered 87 participants who attended a baseline visit. Of this group, investigators assigned 39 patients to SG and 48 to nonsurgical management. Of the original 87 participants, 32 from the SG group and 40 from the nonsurgical group 72 completed the 12-month visit. Age, sex, and race distribution was comparable between the groups, according to the study, as were levels of calciotropic hormones, body composition, and biomechanical spine parameters. Investigators reported also that baseline weight and BMI were higher among participants in the SG group than in the nonsurgical control group.
Participants in the SG group lost a mean of 34.3 (SD, 13.6) kg at 12 months after surgery while weight remained unchanged in the control arm (P<.001). Findings were similar for changes in BMI between groups, with a significant decrease among those who underwent surgery and no significant change among controls. Analysis of biomechanical CT parameters revealed decreases in bone strength, bending stiffness, and in mean and trabecular volumetric BMD among participants in the surgical vs nonsurgical groups (P<.001 for all).
Anote from authors
"Our study adds to the growing body of literature suggesting that adolescents who undergo MBS [metabolic and bariatric surgery] may require postsurgical care to prevent detrimental effects of weight loss on bone accrual. Current strategies of postsurgical care in adults undergoing MBS include optimizing calcium and vitamin D intake and mechanical loading by weight-bearing activities, and these strategies should be applied to adolescents."