Relationship between serum 1,25-dihydroxyvitamin D and mortality in patients with pre-dialysis chronic kidney disease.
BACKGROUND
It is known that vitamin D has many functions besides involvement in calcium metabolism. It has recently been recognized that vitamin D deficiency is associated with mortality, especially in cardiovascular disease (CVD). Vitamin D deficiency is common in end-stage renal disease, but develops from the early stage of chronic kidney disease (CKD). So we investigated whether the serum level of the activated form of vitamin D (1,25-dihydroxyvitamin D) affected mortality in patients with CKD stages 3 and 4.


METHODS
Between January 1, 1995, and June 30, 2006 we measured serum 1,25-dihydroxyvitamin D In 226 patients with CKD stages 3 and 4 and classified the results into two groups depending on whether the level was below (group I) or above (group II) 20 pg/ml. We ended the follow-up period on December 31, 2006. We compared all-cause and cardiovascular mortality between the two groups. We also examined predictors of mortality by using Cox proportional regression analysis.


RESULTS
Two-hundred and twenty-six patients (67 men and 159 women, mean age 67.0) were registered in this study, and groups 1 and 2 comprised 84 and 142 patients, respectively. During the follow-up period 43 patients died. CVD was the major cause of death, followed by infectious disease. The Kaplan-Meier survival curve revealed that all-cause mortality was significantly higher in group I, but a significant difference between CVD mortality in the two groups was not demonstrated. By Cox proportional regression analysis, group I was related to all-cause mortality, but this was not proved to be an independent predictor.


CONCLUSIONS
The results suggested that serum level of 1,25-dihydroxyvitamin D was associated with all-cause mortality in patients with CKD stages 3 and 4.
Inaguma
Daijo
D
Department of Nephrology and Rheumatology, Tosei General Hospital, Nishioiwake-cho 160, Seto, Aichi, 489-8642, Japan. inaguma@tosei.or.jp.
Nagaya
Hiroshi
H
Department of Nephrology and Rheumatology, Tosei General Hospital, Nishioiwake-cho 160, Seto, Aichi, 489-8642, Japan.
Hara
Kazuhiro
K
Department of Nephrology and Rheumatology, Tosei General Hospital, Nishioiwake-cho 160, Seto, Aichi, 489-8642, Japan.
Tatematsu
Miho
M
Department of Nephrology and Rheumatology, Tosei General Hospital, Nishioiwake-cho 160, Seto, Aichi, 489-8642, Japan.
Shinjo
Hibiki
H
Department of Nephrology and Rheumatology, Tosei General Hospital, Nishioiwake-cho 160, Seto, Aichi, 489-8642, Japan.
Suzuki
Sachiyo
S
Department of Nephrology and Rheumatology, Tosei General Hospital, Nishioiwake-cho 160, Seto, Aichi, 489-8642, Japan.
Mishima
Tomoko
T
Department of Nephrology and Rheumatology, Tosei General Hospital, Nishioiwake-cho 160, Seto, Aichi, 489-8642, Japan.
Kurata
Kei
K
Department of Nephrology and Rheumatology, Tosei General Hospital, Nishioiwake-cho 160, Seto, Aichi, 489-8642, Japan.
D000368:Aged; D015415:Biomarkers / Q000097:blood; D002318:Cardiovascular Diseases / Q000097:blood* / Q000209:etiology / Q000401:mortality*; D003141:Communicable Diseases / Q000097:blood / Q000209:etiology / Q000401:mortality; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D016016:Proportional Hazards Models; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000150:complications / Q000401:mortality*; D018570:Risk Assessment; D012720:Severity of Illness Index; D013997:Time Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood* / Q000150:complications / Q000401:mortality*
D015415:Biomarkers; D014807:Vitamin D; C097949:1,25-dihydroxyvitamin D