Serum phosphate and calcium should be primarily and consistently controlled in prevalent hemodialysis patients

Abstract

Mineral metabolism affects mortality in hemodialysis patients and is identified by imbalances in serum phosphate (P), calcium (Ca), and parathyroid hormone (PTH). We examined associations between annual mineral values (P, Ca, PTH) and mortality in a 3-year cohort (Dec 2006-2009) of 128,125 hemodialysis patients using three models, that is, baseline, time-dependent and time-average Cox models. We also examined associations between achieved Japanese guideline targets (P: 3.5-6.0 mg/dL, corrected Ca 8.4-10.0 mg/dL, intact PTH 60-180 mg/dL) and all-cause survival to elucidate which parameter should be controlled as a priority. High and low serum P (>6.0 or ≤ 3.5 mg/dL), high Ca (>9.5 mg/dL), higher PTH (>300 pg/mL) and lower PTH (≤ 60 pg/mL) were significantly associated with high mortality in all three models (P < 0.01). When we examined the association between combination of mineral targets and mortality, patients who achieved all targets simultaneously (20% of subjects, reference) showed lowest mortality. Those who achieved both P and Ca targets showed the same mortality as the reference group. Those who only met P target had a lower risk of death (hazard ratio = 1.17) compared to those that achieved Ca or PTH target (1.41, 1.47, respectively). As time of achieving P and Ca targets increased, all-cause mortalities diminished incrementally, significantly. Mineral metabolism disorder would lead to high mortality in prevalent hemodialysis patients. Among mineral values, P would be the strongest predictor for high mortality. Consistent achievement of P and Ca targets would lead to good survival.