Effect of bone mineral guideline target achievement on mortality in incident dialysis patients: an analysis of the United Kingdom Renal Registry

Abstract

Background: Abnormalities in bone mineral metabolism parameters are common in patients with end-stage kidney disease on dialysis therapy. The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) guidelines propose targets for calcium, phosphate, and intact parathyroid hormone (iPTH) levels in patients undergoing dialysis. However, whether achievement of these targets improves survival is unknown.

Study design: Retrospective cohort study.

Setting & participants: Incident patients on hemodialysis or peritoneal dialysis therapy in the United Kingdom from 2000-2004 who survived at least 12 months.

Predictor: Achievement of KDOQI calcium, phosphate, and iPTH guideline targets during the first year of dialysis therapy.

Outcomes: All-cause mortality in the subsequent 2 years.

Measurements: Calcium, phosphate, and iPTH at quarterly intervals, demographic and comorbid condition data at baseline.

Results: We included 7,076 incident patients (4,947 hemodialysis, 2,129 peritoneal dialysis) in our analysis. Approximately two thirds of patients were men and 21% had diabetes as the cause of kidney failure. Guideline target achievement for each quarter varied from 23%-26% for iPTH level, 43%-47% for calcium level, and 54%-62% for phosphate level targets. In adjusted Cox proportional hazards models, patients who achieved guideline targets in all 4 quarters did not have a survival advantage over patients who never achieved target (P > 0.1 for calcium, phosphate, and iPTH).

Limitations: Missing information about medication use, vitamin D and alkaline phosphatase levels, and dialysate calcium content.

Conclusions: Our findings do not support the use of KDOQI bone mineral guideline achievement as a quality measure for dialysis care. Prospective studies with longer term follow-up are needed to define the optimal cutoff values for calcium, phosphate, and iPTH and assess the effect of guideline implementation on patient survival.