Association between hyperphosphatemia and mortality in patients with terminal chronic renal insuficiency in renal function replacement therapy with peritoneal dyalisis or hemodialysis

A study of the Renal Unit in Villavicencio, 1999-2003

Abstract

Objective: to evaluate the risk of mortality in patients with renal chronic disease stage V with increased serum phosphorus levels to more than 6.5 mg%.

Design: retrospective cohort with 273 patients in dialysis, 70% in peritoneal dialysis and 30% in hemodialysis between 1999-2003 in a single dialysis center in Villavicencio (Colombia).

Methods: the mortality rate for the patients with increased phosphorus levels to more than de 6.5 mg% was calculated and the survival analysis was made with the Kaplan-Meier method.

Results: the mean of age at the beginning of dialysis was 52.7 years, 30.1% diabetics, 46.2% high blood pressure; the mean phosphorus level was 4.73 mg%, mean serum calcium 9.05 mg% and PTHi 173, 7 UI/ml. 98 death cases were recorded. The survival curves for the patients with mean phosphorus > 6.5 mg% showed a Log Rank 3.9 (p=0.048) and a mortality rate in 1.32 (IC 95% 1.08-1.63). For the subjects with increased phosphorus levels to more than 5.5 mg% there were no statistically significant differences p=0.0785), with a mortality rate 1.12 (IC 95% 0.93-1.35). The 4.3% of the subjects showed phosphorus increase of more than 6.5 mg%.

Conclusions: hyperphosphatemia (>6.5 mg%) is a risk factor for mortality in end stage renal disease (stage V) as well as in renal replacement therapy. It is recommended to maintain the level of phosphorus below 5.5 mg% to reduce the increased risk of death.