The nephrologist's role in the management of calcium-phosphorus metabolism in patients with chronic kidney disease.
BACKGROUND
In patients with chronic kidney disease (CKD), timely referral to a nephrologist has been shown to improve outcomes, but the specific care measures mediating these superior outcomes have not been sufficiently described.


METHODS
In a cohort of 3014 patients with CKD, we evaluated whether they had any indicators of calcium-phosphorus metabolism management prior to renal replacement therapy (RRT). These included measurement of parathyroid hormone (PTH) or vitamin D metabolites, or receipt of calcitriol or calcium-containing phosphate binders (CCPB) prior to RRT. Control patients without such care were selected by risk-set matching. We used multivariate conditional logistic regression analysis to test whether use of these interventions was associated with prior nephrologist consultation. We then used Cox proportional hazards models to assess whether implementation of such care was associated with differences in 1-year mortality once RRT was instituted.


RESULTS
Only 3.4% of CKD patients had their PTH assessed prior to RRT, and 0.3% had vitamin D status measured. Use of calcitriol (12.2%) and CCPBs (16%) was slightly more prevalent. Seeing a nephrologist was highly associated with use of the tests and drugs studied (odds ratio, 1.28 to 6.46; all P values <0.001), but care by generalists or other specialists was not. Management of calcium-phosphorus metabolism was independently associated with a 35% decreased likelihood of death (hazards ratio=0.65; 95%CI, 0.51 to 0.84) in the first year of RRT.


CONCLUSIONS
Improvements in management of calcium-phosphorus metabolism in patients with CKD are attributable to nephrologist care and appear to mediate the survival benefit seen in patients who see a nephrologist relatively early in the course of their CKD.
Winkelmayer
Wolfgang C
WC
Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA.
Levin
Raisa
R
Avorn
Jerry
J
D000368:Aged; D000369:Aged, 80 and over; D002117:Calcitriol / Q000627:therapeutic use; D002118:Calcium / Q000378:metabolism* / Q000627:therapeutic use; D002120:Calcium Channel Agonists / Q000627:therapeutic use; D015331:Cohort Studies; D005260:Female; D006801:Humans; D006961:Hyperparathyroidism / Q000188:drug therapy* / Q000378:metabolism / Q000401:mortality; D007676:Kidney Failure, Chronic / Q000188:drug therapy* / Q000378:metabolism / Q000401:mortality; D008297:Male; D008875:Middle Aged; D009398:Nephrology; D010281:Parathyroid Hormone / Q000097:blood; D010758:Phosphorus / Q000378:metabolism*; D010818:Practice Patterns, Physicians'; D014807:Vitamin D / Q000097:blood
D002120:Calcium Channel Agonists; D010281:Parathyroid Hormone; D014807:Vitamin D; D010758:Phosphorus; D002117:Calcitriol; D002118:Calcium