Oral Presentation 6th Annual Scientific Meeting of the Australian and New Zealand Society for Sarcopenia and Frailty Research 2024

Interactions between bone and muscle quality on mortality risk in 1,353 men (aged 77-101) over 6 years: A prospective cohort study utilizing high-resolution bone imaging and stable muscle isotopes (#11)

Ben Kirk 1 2 , Stephanie L Harrison 3 , Jesse Zanker 2 , Andrew Burghardt 4 , Eric Orwoll 5 , Peggy M Cawthon 3 , Gustavo Duque 6
  1. Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, Melbourne, Victoria, Australia
  2. Department of Medicine, Melbourne Medical School, Melbourne, Victoria, Australia
  3. Research Institute, California Pacific Medical Center, San Francisco, CA, USA
  4. Department of Radiology & Biomedical Imaging, University of California, San Francisco, CA, USA
  5. Division of Endocrinology, Diabetes and Clinical Nutrition, School of Medicine, Oregon Health & Science University, Portland, OR, USA
  6. Bone, Muscle & Geroscience Group, Research Institute of the McGill University Health Centre, Montreal, QC, Canada

Background: We investigated whether there is a synergistic association of bone and muscle quality on mortality risk.

Methods: Data from the Osteoporotic Fractures in Men study (MrOS) was used to build Cox proportional hazards models. Predictors included HR-pQCT total volumetric bone mineral density (BMD) (mg/cm3) and bone strength (failure load, Newtons) at distal radius and tibia; DXA BMD at total hip (g/cm2); HR-pQCT muscle volume (mm3) and density (mg/cm3) at diaphyseal tibia (calf); D3-creatine dilution (D3Cr) muscle mass (whole-body, kg); and grip strength (kg) and leg force (newtons/kg). Deaths were ascertained via death certificates. Covariates including age, race, clinical center, alcohol, smoking, comorbidities, limb length, weight, % fat, physical activity and cognitive function were included statistical analysis.

Results: 1,353 men with a mean age of 84.1 ± 4.0 years (77-101 years, 91.7% white) were followed for 6.20 ± 2.24 years. A total of 558 (41.2%) men died. In unadjusted models using continuous predictors, interaction terms were significant in all models including muscle mass or muscle volume with bone variables (p<0.05); interaction terms were not significant for other muscle variables (muscle density, grip strength or leg force). In multivariable-adjusted models, the association of hip BMD on mortality risk was significant when muscle mass was low (<50th percentile; HR= 0.72 [per SD increment in hip BMD]; 95% CI 0.61-0.85, p<0.001) vs. high (>50th percentile; HR= 0.97; 95% CI 0.82-1.14, p=0.680). Likewise, in multivariable-adjusted models, the association of hip BMD on mortality risk was significant when muscle volume was low (<50th percentile; HR= 0.74; 95% CI 0.63-0.87, p<0.001) vs. high (>50th percentile; HR=1.13; 95% CI 0.95-1.35, p=0.167). Interchanging hip BMD for bone strength at distal limbs resulted in similar findings on mortality risk (p<0.001 to 0.056 when muscle mass or muscle volume was low vs. high [p>0.05] in multivariable-adjusted models).

Conclusions: In this prospective cohort study of older men, we found strong evidence for a synergistic association of bone and muscle quality on mortality risk. Findings were consistent across all bone anatomical sites and were not materially altered by interchanging D3Cr muscle mass for HR-pQCT muscle volume.