title: Vitamin D deficiency predicts decline in kidney allograft function: a prospective cohort study.
abstract: BACKGROUND
  Vitamin D, often deficient in kidney transplant (KTx) recipients, has potential immunomodulatory effects.
  
  
  OBJECTIVE
  This study aimed to evaluate whether vitamin D status affects the rate of decline in kidney allograft function.
  
  
  METHODS
  The study included a prospective cohort of 264 ambulatory KTx recipients at a single Japanese center.
  
  
  METHODS
  We measured the baseline 25-hydroxyvitamin D (25D) concentration and examined its association with annual decline in estimated glomerular filtration rate (eGFR). Secondary outcome was rescue treatment with iv methylprednisolone (IV-MP) as an index of rejection episodes.
  
  
  RESULTS
  The mean serum 25D concentration was 17.1 (SD 6.5) ng/mL, and 68.4% patients had vitamin D inadequacy or deficiency. Time after KTx was a significant effect modifier for the association of serum 25D concentration with annual eGFR change and need for IV-MP (P for interaction < .1). We divided patients according to the median time after KTx (10 y) and found that low vitamin D was significantly associated with a rapid eGFR decline at less than 10 years after KTx but not at 10 or more years after KTx. The same was true for rescue treatment with IV-MP. Overall, propensity score matching showed independent associations of low vitamin D with both outcomes. Stratified matching confirmed pronounced associations at less than 10 years after KTx.
  
  
  CONCLUSIONS
  Vitamin D deficiency predicts a rapid decline in eGFR and need for IV-MP at less than 10 years after KTx. Future studies are warranted to evaluate the clinical efficacy of vitamin D supplementation.
authors.affiliation: Departments of Geriatric Medicine and Nephrology (Y.O., I.M., H.R., Y.I.), Comprehensive Kidney Disease Research (T.H., Y.T.), Advanced Technology for Transplantation (N.I., J.K., S.T.), and Specific Organ Regulation (Urology) (M.O., K.Y., N.N.), Osaka University Graduate School of Medicine, Suita 565-0871, Osaka, Japan; Department of Kidney Disease and Hypertension (K.T.), Osaka General Medical Center, Osaka 558-0056, Osaka, Japan; Department of Internal Medicine (N.F.), Hyogo Prefectural Nishinomiya Hospital, Nishinomiya 662-0918, Hyogo, Japan; and Takahashi Clinic (Y.K.), Toyonaka 570-0027, Osaka, Japan.
authors.forename: Yoshitsugu
authors.initials: Y
authors.lastname: Obi
authors.forename: Takayuki
authors.initials: T
authors.lastname: Hamano
authors.forename: Naotsugu
authors.initials: N
authors.lastname: Ichimaru
authors.forename: Kodo
authors.initials: K
authors.lastname: Tomida
authors.forename: Isao
authors.initials: I
authors.lastname: Matsui
authors.forename: Naohiko
authors.initials: N
authors.lastname: Fujii
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Okumi
authors.forename: Jun-ya
authors.initials: JY
authors.lastname: Kaimori
authors.forename: Koji
authors.initials: K
authors.lastname: Yazawa
authors.forename: Yukito
authors.initials: Y
authors.lastname: Kokado
authors.forename: Norio
authors.initials: N
authors.lastname: Nonomura
authors.forename: Hiromi
authors.initials: H
authors.lastname: Rakugi
authors.forename: Shiro
authors.initials: S
authors.lastname: Takahara
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Isaka
authors.forename: Yoshiharu
authors.initials: Y
authors.lastname: Tsubakihara
mesh_terms: D000328:Adult; D000368:Aged; D015331:Cohort Studies; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology; D006084:Graft Rejection / Q000097:blood / Q000209:etiology* / Q000503:physiopathology; D006085:Graft Survival / Q000502:physiology*; D006801:Humans; D016030:Kidney Transplantation; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications* / Q000503:physiopathology
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D