Osteosarcopenia in patients with non-dialysis dependent chronic kidney disease

Introduction: Chronic kidney disease (CKD) is associated with a reduction in bone mineral density (BMD), but less is understood regarding the relation between BMD and muscle mass, especially in non-dialysis dependent-CKD (NDD-CKD). The aim of this study was to explore the prevalence and association of low BMD (osteopenia and osteoporosis) with markers of muscle mass and function in patients with NDD-CKD.

Methodology: This cross-sectional observational study included patients with NDD-CKD. Routine biochemical parameters including those related to mineral and bone metabolism were evaluated. Body composition was assessed by dual energy x-ray absorptiometry (DXA) for BMD (g/cm²), total and trunk body fat (%), total lean soft tissue (LST; kg), and appendicular skeletal muscle mass (ASM; kg) as the sum of the LST from the limbs. The latter two variables were used as markers of muscle mass, together with its height indexed values: ASM/height² as ASM index (ASMI; kg/m²), and LST/height² as LST index (LSTI, kg/m²). Muscle quality index (MQI) was calculated as handgrip strength (HGS)/mean ASM_arms (kg/kg). Osteosarcopenia was defined according to referenced cut-points for patients presenting with low ASMI, HGS and BMD.

Results: Patients (n = 257, 57.6% males) had a mean age = 64.8 ± 12.9 years, estimated glomerular filtration rate (eGFR) = 30.1 ± 12.9 ml/min and body mass index (BMI) = 26.8 ± 4.8 kg/m². Patients with low BMD (39.4%) presented with lower BMI, LST, LSTI, ASM and ASMI for both sexes. BMD was positively and significantly correlated with LST, LSTI, ASM, ASMI and HGS. Low ASM was associated with low BMD (odds-ratio-OR; 95% confidence interval-CI: males OR = 4.54, 2.02-10.21; females OR = 4.45, 1.66-11.93). Linear multiple regression analysis (adjusted for sex and eGFR) showed significant associations between T-score with HGS (R² = 0.288, R² adjusted = 0.272, standardized coefficient β = 0.536, p < 0.0001) and also with MQI (R² = 0.095, R² adjusted = 0.075, standardized coefficient β = 0.309, p = 0.024). Osteosarcopenia was present in about 7% of participants and similarly distributed between sexes.

Conclusion: Low BMD was prevalent, and associated with low markers of muscle mass and quality, in NDD-CKD patients of both sexes. In view of the known significance of these conditions, targeted interventions are needed to optimize body composition and functional status of these patients.