Sparing effect of peritoneal dialysis vs hemodialysis on BMD changes and its impact on mortality.

INTRODUCTION: Bone loss in end stage renal disease (ESRD) patients associates with fractures, vascular calcification, cardiovascular disease (CVD) and increased mortality. We investigated factors associated with changes of bone mineral density (ΔBMD) during the initial year on dialysis therapy and associations of ΔBMD with subsequent mortality in ESRD patients initiating dialysis. MATERIALS AND METHODS: In 242 ESRD patients (median age 55 years, 61% men) starting dialysis with peritoneal dialysis (PD; n = 138) or hemodialysis (HD; n = 104), whole-body dual-energy X-ray absorptiometry (DXA), body composition, nutritional status and circulating biomarkers were assessed at baseline and 1 year after dialysis start. We used multivariate linear regression analysis to determine factors associated with ΔBMD, and fine and gray competing risk analysis to determine associations of ΔBMD with subsequent mortality risk. RESULTS: BMD decreased significantly in HD patients (significant reductions of BMDtotal and BMDleg, trunk, rib, pelvis and spine) but not in PD patients. HD compared to PD therapy associated with negative changes in BMDtotal (ß=- 0.15), BMDhead (ß=- 0.14), BMDleg (ß=- 0.18) and BMDtrunk (ß=- 0.16). Better preservation of BMD associated with significantly lower all-cause mortality for ΔBMDtotal (sub-hazard ratio, sHR, 0.91), ΔBMDhead (sHR 0.91) and ΔBMDleg (sHR 0.92), while only ΔBMDhead (sHR 0.92) had a beneficial effect on CVD-mortality. CONCLUSIONS: PD had beneficial effect compared with HD on BMD changes during first year of dialysis therapy. Better preservation of BMD, especially in bone sites rich in cortical bone, associated with lower subsequent mortality. BMD in cortical bone may have stronger association with clinical outcome than BMD in trabecular bone.