Kidney function, bone health, and vascular calcifications in patients with CKD II – IV: A 2 – 3 year prospective study with bone biopsies

Background: Patients with chronic kidney disease (CKD) have serum, bone, and vascular abnormalities presenting as chronic kidney disease-mineral bone disorder (CKD-MBD) syndrome. This study sought to identify the parameters with the greatest relative impact on progression of CKD-MBD abnormalities. Materials and methods: This prospective study measured 237 parameters including serum markers, clinical variables, dual-energy X-ray absorptiometry (DXA) measurements, vascular calcifications, and histomorphometric results from bone samples obtained at baseline and after 2 – 3 years. Relative impact of these parameters on kidney function, bone changes, and vascular calcification were assessed using machine learning, a subset of artificial intelligence analyses. Results: Baseline estimated glomerular filtration rate (eGFR) values ranged from 18 to 70 mL/min and declined in 52% of subjects by at least 3.3% annually during the study. These declines in eGFR were associated with changes in specific serum markers, bone quantity decreases, and bone quality alterations, but not with arterial calcifications. Arterial calcifications were associated with collagen crosslinking heterogeneity, serum phosphorus, diuretics and atorvastatin treatment, but not with kidney function. Baseline collagen crosslinking heterogeneity was an important factor impacting progression of coronary, but not aortic calcification. Baseline serum phosphorus was a factor primarily associated with progression of aortic calcification. Conclusion: Machine learning revealed specific bone and vascular abnormalities occurring early during loss of kidney function. Bone, vascular, blood, medication use, and other parameters were identified impacting the presence and progression of arterial calcification and altering bone quality and quantity in this understudied patient population. Serum phosphorus levels considered normal impacted progression of arterial calcification. Identification of these parameters and their relative importance enhances our understanding of CKD progression and should improve patient care.