Obesity may ‘blunt’ effect of race on bone parameters
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Advantages in bone parameters that may contribute to reduced fracture risk among Black vs. white adolescents and young adults may be attenuated by obesity, according to findings published in Bone.
“We have published previous work that demonstrated differences in bone by race and ethnicity, but we had not evaluated this phenomenon in young patients with obesity,” Fatima Cody Stanford, MD, MPH, MPA, FAAP, FACP, FAHA, FTOS, an obesity medicine physician scientist at Massachusetts General Hospital and Harvard Medical School, told Healio. “While African Americans have higher strength at the distal radius and tibia and cortical volumetric bone density, at the distal tibia, the areal bone mineral density z scores do not differ in African American vs. white youths with obesity. At the distal radius, volumetric BMD and bone geometry do not differ between the two groups. As such, it appears that moderate to severe obesity attenuates racial and ethnic differences commonly seen in bone parameters.”
In a cross-sectional study, Stanford and colleagues analyzed data from 72 adolescents and young adults with moderate to severe obesity aged 13 to 24 years (24 Black participants; mean age, 18 years; median BMI, 44.8 kg/m²). Participants underwent DXA scans to assess bone mineral content, body composition and areal BMD at the hip, spine and femoral neck, as well as high-resolution peripheral quantitative CT (HR-pQCT), extended cortical analysis and micro-finite element analysis. All bone parameters were adjusted for height and sex in multivariable regression analysis.
Comparing Black and white participants, the researchers did not observe between-group differences for BMD z scores at the femoral neck, total hip, lumbar spine and whole-body BMD z score; however, whole-body BMD z score trended higher among Black participants vs. white participants (P = .081).
At the non-weight-bearing distal radius, researchers found that Black participants had higher total area (P = .049) and trended to have higher pore diameter vs. white participants (P = .074). Stiffness and failure load were similarly higher among Black participants vs. white participants (P = .031 and .047, respectively). There were no between-group differences in total, cortical and trabecular volumetric BMD, cortical and trabecular cross-sectional area, cortical thickness, or any component of trabecular microarchitecture.
At the weight-bearing distal tibia, cortical volumetric BMD was higher among Black participants vs. white participants (P = .012), with no between-group differences for total and trabecular volumetric BMD, total, cortical or trabecular cross-sectional area, cortical thickness or porosity. Stiffness as measured by micro-finite element analysis trended higher among Black vs. white participants (P = .052), as did failure load (P = .048).
“We demonstrate that many differences in bone components that usually confer the lower risk of fracture observed in African Americans compared to whites are either no longer evident or are blunted in the context of moderate/severe obesity,” the researchers wrote. “Most bone geometry, microarchitecture and density parameters that are typically higher in African American adolescents and adults compared to whites, such as cortical area, trabecular thickness, total and trabecular volumetric BMD, as well as areal BMD z scores did not significantly differ between African Americans and whites in our participants with obesity.”
The researchers noted that it remains unclear whether the findings translate to a reduction in the assumed protection against fractures among Black adults vs. white adults with obesity compared with those without obesity.
“We need long-term studies to demonstrate whether bone density similarities and differences in young patients with moderate to severe obesity change or persist over time,” Stanford said.
For more information:
Fatima Cody Stanford, MD, MPH, MPA, FAAP, FACP, FAHA, FTOS, can be reached at the Massachusetts General Hospital Weight Center, 50 Staniford Street, Fourth Floor, 50-S-4-430, Boston, MA 02114; email: fstanford@mgh.harvard.edu; Twitter: fstanfordmd.
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