Population-level associations of achievement of targets for bone-mineral markers with survival in haemodialysis patients with mildly elevated intact-PTH levels: a case-cohort study.

Achieving calcium, phosphorus, and intact parathyroid hormone (PTH) targets helps improve dialysis population outcomes. We aimed to assess the population-level associations of achievement of those targets with survival using population-attributable-fractions (PAFs). We conducted a case-cohort study using data from 8229 haemodialysis patients with mildly elevated intact PTH, treated at 86 dialysis facilities in Japan. We examined associations among calcium, phosphorus, intact PTH, and mortality over 3 years. We estimated PAFs for achieving the targets of calcium, phosphorus, and intact PTH from the adjusted hazard ratios by Cox regression models. Proportions within the recommended range were 55.8%, 63.3%, and 39.1% for calcium (8.4-10.0 mg/dL), phosphorus (3.5-6.0 mg/dL) and intact PTH (60-240 pg/mL), respectively. The mortality rate was 5.7 per 100 person-years. Mortality was independently associated with non-achievement of targets. Regarding the population-level impact, statistically significant PAFs were found for achieving the combination of calcium and phosphorus (8.8%; 95% CI, 1.1-16.0). Further, PAF for combined calcium, phosphorus, and intact PTH was the largest (16.8%; 95% CI, 5.6-30.4). In conclusion, there might be additive and substantial population-level associations between survival and the achievement of calcium, phosphorus, and intact-PTH targets in the haemodialysis population with mildly elevated intact PTH.