Calcium, phosphorus, cardiovascular events and all-cause mortality in hemodialysis patients: a single-center retrospective cohort study to reassess the validity of the Japanese Society for Dialysis Therapy guidelines

Mineral and bone disorders frequently cause cardiovascular complications and mortality in hemodialysis patients, but few observational studies of Japanese patients have investigated this matter. A retrospective cohort study of 99 patients (53 males, 46 females; mean age: 65 +/- 12 year; 38% with diabetes mellitus) on maintenance hemodialysis in our dialysis center was conducted. Mean serum Ca, P and intact parathyroid hormone (iPTH) levels were 9.2 +/- 0.9 mg/dL, 6.1 +/- 1.7 mg/dL, and 233 +/- 333 pg/mL, respectively. The cutoff values for each of these three parameter were defined according to the target ranges recommended by the Japanese Society for Dialysis Therapy (JSDT) guidelines (Ca: 8.4-10.0 mg/dL; P: 3.5-6.0 mg/dL; iPTH: 60-180 pg/mL). During a 45-month follow up, patients with all parameters outside the target ranges showed the highest incidence of cardiovascular events and all-cause deaths (16.6 and 29.2 per 1000 person-years, respectively). The relative risks of cardiovascular events and all-cause deaths were analyzed by multivariate Cox regression models. The hazard ratio (HR) for cardiovascular events was significantly lower for patients who achieved serum Ca and P objectives compared with others (HR: 2.12; 95% CI: 1.04-4.34; P < 0.05), and similar differences were observed for all-cause deaths (HR: 3.10; 95% CI: 1.13-8.53; P < 0.05). However, the relationship between iPTH levels and each of the endpoints was less pronounced. The results of this study provide support for the JSDT guidelines, which give priority to the control of serum Ca and P levels over the control of parathyroid function.