Consistent control of mineral and bone disorder in incident hemodialysis patients

Abstract

Background and objectives: In 2003, the National Kidney Foundation introduced guidelines for the control of parathyroid hormone, calcium, and phosphorus in hemodialysis patients.

Design, setting, participants, & measurements: A cohort study was conducted of 22,937 incident hemodialysis patients who were identified from a large national provider between July 1, 2000, and June 30, 2002, and followed through June 30, 2004. Consistent achievement was determined (1) as the simultaneous control of multiple markers over time and (2) as the time in target for each marker during the first year of dialysis. Mortality risk was assessed with Cox proportional hazards models.

Results: In the simultaneous control analysis, patients who achieved target for none of the markers had a 51% greater risk for death than those who achieved target for all three markers (reference group). Patients who achieved any target for any single marker had a 35 to 39% higher risk for death, and patients who achieved target for any two of the three markers had a 15 to 21% higher risk for death compared with the reference group. In the time in target analysis, patients with parathyroid hormone in target for 4 quarters had a 25% lower risk for death compared with those who did so for <or=1 quarter (reference group). Patients with calcium in target for 4 quarters had a 14% lower risk, and patients with phosphorus in target for 4 quarters had a 38% lower risk.

Conclusions: Consistent control of the markers of bone metabolism and disease within published targets is a strong predictor of survival in hemodialysis patients.

Figure 1.

Proportion of patients who met target by calendar quarter over 2 yr (n = 13,015). Bars show the percentage of patients who met Kidney Disease Outcomes Quality Initiative (KDOQI) targets for parathyroid hormone (PTH), calcium (Ca), phosphorus (P), and Ca-P product (Ca × P) for each quarter after beginning hemodialysis. Only patients who survived for a minimum of 2 yr after hemodialysis initiation are included.

Figure 2.

Simultaneous control: Relationship between KDOQI targets achieved and risk for death (model 1). Hazard ratios (HR) and 95% confidence intervals (CI) for various combinations of achieving KDOQI target values for PTH, Ca, and P are shown. Values in parentheses represent the proportion of patients in each category at baseline.

Figure 3.

Simultaneous control: Relationship between KDOQI targets achieved and risk for death (model 2). HR and 95% CI for various combinations of achieving KDOQI target values for PTH and Ca × P. Values in parentheses represent the proportion of patients in each category at baseline.

Figure 4.

Time in target: Relationship between quarters in target and risk for death. HR and 95% CI for number of quarters in target PTH, Ca, and P. Values in parentheses represent the proportion of patients in each category at baseline.