Higher Intra-Dialysis Serum Phosphorus Reduction Ratio as a Predictor of Mortality in Patients on Long-Term Hemodialysis.

BACKGROUND Rapid shifting between extracellular and intracellular phosphorus can occur during dialysis sessions, which can cause aberrant intracellular signaling in long-term hemodialysis (LTHD) patients. However, the effect of these intra-dialysis fluctuations of phosphorus on clinical outcomes has not been examined. Therefore, we investigated the relationship between intradialysis serum phosphorus reduction ratio (IDSPRR) and mortality in LTHD patients. MATERIAL AND METHODS This was a retrospective, observational cohort study to assess the predictive power of IDSPRR (>0.63 vs. ≤0.63) on mortality in a total of 805 LTHD patients. All these fatal events were analyzed using the Cox proportional hazards regression model. RESULTS After multivariable analysis, baseline IDSPRR higher than 0.63 was significantly predictive of all-cause mortality (hazard ratio [HR]: 1.58; 95% confidence interval [CI]: 1.10-2.26), but not for cardiovascular (CV) mortality (HR: 1.41; 95% CI: 0.91-2.18). However, when time-varied IDSPRRs were applied, a value greater than 0.63 was not only significantly predictive of all-cause mortality (HR: 1.74, 95% CI: 1.16-2.63), but also CV mortality (HR: 2.04, 95% CI: 1.23-3.40). CONCLUSIONS High IDSPRR (>0.63) is independently associated with increased all-cause and CV mortality, which shows the negative effect of rapid intracellular phosphorus-shifting on LTHD patients.