Calcium, phosphorus, PTH and death rates in a large sample of dialysis patients from Latin America. The CORES Study

Abstract

Background: Mineral metabolism parameters may play a role in the survival of patients with chronic kidney disease (CKD).

Methods: In the CORES Study, we analysed the association between calcium, phosphorus and PTH and mortality (all-cause and cardiovascular) in 16 173 haemodialysis (HD) patients over 18 years from six Latin American countries, who underwent haemodialysis up to 54 months. Unadjusted, case-mix-adjusted and time-dependent multivariable-adjusted hazard ratio (HR) of death were calculated for categories of serum albumin-corrected calcium (Ca(Alb)), phosphorus and PTH using as 'reference values' the range in which the lowest death rate was observed. Age, gender, vitamin D treatment, diabetes, vintage, vascular access, weight, blood pressure and laboratory variables (serum albumin, haemoglobin, creatinine, ferritin and Kt/V) were used as confounding variables.

Results: Low (<9.5 mg/dL) and high (>10.5 mg/dL) Ca(Alb) increased the HR for all-cause mortality. Low (<9.0 mg/dL) Ca(Alb) increased the HR for cardiovascular mortality. High phosphorus (>5.5 mg/dL) increased the HR for both all-cause and cardiovascular mortality. Low phosphorus (<4.0 and <3.0 mg/dL) increased the HR for both all-cause and cardiovascular mortality. Furthermore, low (<150 pg/mL) and high (>500 and >300 pg/mL) PTH increased the HR for both all-cause and cardiovascular mortality. In addition, only phosphorus >6.0 mg/dL increased the HR for cardiovascular hospitalizations. No effect was observed with Ca(Alb) or PTH.

Conclusions: In summary, in 16,173 HD patients, elevated and reduced serum levels of albumin-corrected calcium, phosphorus and PTH levels were associated with increments in all-cause mortality. Similar results were obtained when only cardiovascular mortality was analysed.