Meta-analysis: vitamin D compounds in chronic kidney disease.
BACKGROUND
Vitamin D compounds are widely used to prevent and treat secondary hyperparathyroidism.


OBJECTIVE
To determine whether vitamin D therapy improves biochemical markers of mineral metabolism and cardiovascular and mortality outcomes in chronic kidney disease.


METHODS
MEDLINE (January 1966 to July 2007), EMBASE (January 1980 to July 2007), and Cochrane databases were searched without language restriction.


METHODS
Randomized, controlled trials of vitamin D compounds in chronic kidney disease were identified.


METHODS
Two authors independently extracted data.


RESULTS
Seventy-six trials were identified for inclusion; 3667 participants were enrolled. Vitamin D compounds did not reduce the risk for death, bone pain, vascular calcification, or parathyroidectomy. Compared with placebo, established vitamin D sterols were associated with an increased risk for hypercalcemia (relative risk, 2.37 [95% CI, 1.16 to 4.85]) and hyperphosphatemia (relative risk, 1.77 [CI, 1.15 to 2.74]) but did not show a consistent reduction in parathyroid hormone (PTH) levels. Compared with placebo, more recently developed vitamin D analogues were associated with hypercalcemia (relative risk, 5.15 [CI, 1.06 to 24.97]) but not hyperphosphatemia, and levels of PTH were reduced (weighted mean difference, -10.77 pmol/L [CI, -20.51 to -1.03 pmol/L]). For suppression of PTH, intravenous administration was superior to oral vitamin D, but higher intravenous doses were used.


CONCLUSIONS
Few studies reported patient-level outcomes, including mortality (8 of 76 trials), and only 5 trials directly compared the effects of treatment with newer vitamin D compounds versus established ones. Heterogeneity in some comparisons remained unexplained by metaregression analyses.


CONCLUSIONS
Vitamin D compounds do not consistently reduce PTH levels, and beneficial effects on patient-level outcomes are unproven. The value of vitamin D treatment for people with chronic kidney disease remains uncertain.
Palmer
Suetonia C
SC
Department of Medicine, Christchurch School of Medicine and Health Sciences, Christchurch, New Zealand. strippoli@negrisud.it
McGregor
David O
DO
Macaskill
Petra
P
Craig
Jonathan C
JC
Elder
Grahame J
GJ
Strippoli
Giovanni F M
GF
D004334:Drug Administration Schedule; D006801:Humans; D006934:Hypercalcemia / Q000139:chemically induced; D006962:Hyperparathyroidism, Secondary / Q000517:prevention & control*; D054559:Hyperphosphatemia / Q000139:chemically induced; D007676:Kidney Failure, Chronic / Q000097:blood / Q000150:complications*; D010281:Parathyroid Hormone / Q000097:blood; D016032:Randomized Controlled Trials as Topic; D014807:Vitamin D / Q000009:adverse effects / Q000627:therapeutic use*; D014815:Vitamins / Q000009:adverse effects / Q000627:therapeutic use*
D010281:Parathyroid Hormone; D014815:Vitamins; D014807:Vitamin D