The findings of our observational study confirm the existence of a grey zone, in which precise biochemical targets are difficult to define, with the exception of avoiding extreme values. Given the absence of intervention trials proving the clinical usefulness of phosphorus control, and pending the results of large clinical trials on the effect of optimal PTH and calcium control on hard outcomes, the present findings may help to refine future recommendations for the treatment of chronic haemodialysis patients.

Dialysis patients exhibit an inverse, L- or U-shaped association between blood pressure and mortality risk, in contrast to the linear association in the general population. We prospectively studied 9333 hemodialysis patients in France, aiming to analyze associations between predialysis systolic, diastolic, and pulse pressure with all-cause mortality, cardiovascular mortality, and nonfatal cardiovascular endpoints for a median follow-up of 548 days. Blood pressure components were tested against outcomes in time-varying covariate linear and fractional polynomial Cox models. Changes throughout follow-up were analyzed with a joint model including both the time-varying covariate of sequential blood pressure and its slope over time. A U-shaped association of systolic blood pressure was found with all-cause mortality and of both systolic and diastolic blood pressure with cardiovascular mortality. There was an L-shaped association of diastolic blood pressure with all-cause mortality. The lowest hazard ratio of all-cause mortality was observed for a systolic blood pressure of 165 mm Hg, and of cardiovascular mortality for systolic/diastolic pressures of 157/90 mm Hg, substantially higher than currently recommended values for the general population. The 95% lower confidence interval was approximately 135/70 mm Hg. We found no significant correlation for either systolic, diastolic, or pulse pressure with myocardial infarction or nontraumatic amputations, but there were significant positive associations between systolic and pulse pressure with stroke (per 10-mm Hg increase: hazard ratios 1.15, 95% confidence interval 1.07 and 1.23; and 1.20, 1.11 and 1.31, respectively). Thus, whereas high pre-dialysis blood pressure is associated with stroke risk, low pre-dialysis blood pressure may be both harmful and a proxy for comorbid conditions leading to premature death.

Phosphorus (Pi) retention linked to chronic renal failure (CRF) favors secondary hyperparathyroidism (HPT). Reduction of Pi and protein intake has been shown to prevent the development of HPT in CRF. The aim of the present study was to assess in patients with advanced CRF the long-term effects on phosphate and calcium metabolism of a low-Pi (5-7 mg/kg/day), low-protein (0.4 g/kg/day) diet providing 300 mg/day calcium (Ca) and supplemented with amino acids and ketoacids, Ca carbonate (400-800 mg/day) and vitamin D₂ (1,000 IU/day). Twenty-nine patients with advanced CRF (glomerular filtration rate (GFR) 13.7 ± 4.5 ml/min) were selected for the study, on the basis of a follow-up of a least 2 years and a satisfactory compliance to the prescribed diet. At the start of the study, biological evidence of HPT was present with increased plasma PTH concentration (144 ± 95 pg/ml), increased plasma Pi (1.57 ± 0.33 mmol/l), an increase in alkaline phosphatase activity and plasma osteocalcin concentration. Plasma PTH concentration was positively correlated with plasma Pi and inversely with plasma Ca concentrations and GFR. Pi and protein restriction induced a significant correction of HPT within 3 months after starting the diet. After 2 years of diet, despite the diminution of GFR (11.1 ± 3.7 ml/min, p < 0.0001), plasma PTH was still lower than at the start of the diet (88 ± 57 pg/ml, p < 0.01), as was plasma Pi (1.32 ± 0.24 mmol/l, p < 0.001), total plasma Ca being higher (p < 0.01). Plasma PTH levels were correlated only to plasma Ca concentrations. However, variations in plasma PTH concentrations were correlated with changes in plasma Ca and Pi concentrations, but not with changes in GFR. Plasma calcitriol concentrations (measured in 14 patients) did not increase significantly. The results of the present study suggest that Pi and protein restriction with calcium supplementation and without calcitriol supplementation in patients with advanced CRF may induce a lasting correction of HPT, potentially mediated by the reduction of plasma Pi and the increase of plasma Ca concentrations, independently of plasma calcitriol.

In this large 2008 cohort of elderly haemodialysis patients, it appears easier to control serum parameters of CKD-MBD as compared to younger dialysis patients. A better control of serum phosphorus was observed, with less phosphate binder and reduced cinacalcet dosage.

No abstract