title: Serum 25-hydroxyvitamin D deficiency and the 5-year incidence of CKD.
abstract: BACKGROUND
  Low serum 25-hydroxyvitamin D (25[OH]D) levels have been associated with chronic kidney disease in cross-sectional studies. However, this association has not been studied prospectively in a large general population-based cohort.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  6,180 adults 25 years or older participating in the baseline and 5-year follow-up phases of the Australian Diabetes, Obesity and Lifestyle (AusDiab) Study.
  
  
  METHODS
  Serum 25(OH)D levels <15 ng/mL were considered deficient.
  
  
  METHODS
  Incident chronic kidney disease was defined as being negative at baseline but positive after 5 years for (1) reduced estimated glomerular filtration rate (eGFR; <60 mL/min/1.72 m²) or (2) albuminuria (spot urine albumin-creatinine ratio ≥2.5 mg/mmol [≥22.1 mg/g] for men and ≥3.5 mg/mmol [≥30.9 mg/g] for women).
  
  
  RESULTS
  623 (10.9%) participants were vitamin D deficient, 161 developed incident reduced eGFR, and 222 developed incident albuminuria. In participants with and without vitamin D deficiency, annual age-standardized incidences were 0.92% (95% CI, 0.56%-1.30%) and 0.59% (95% CI, 0.51%-0.68%), respectively, for eGFR <60 mL/min/1.72 m² and 1.50% (95% CI, 1.06%-1.95%) and 0.66% (95% CI, 0.56%-0.76%), respectively, for albuminuria. In multivariate regression models, vitamin D deficiency was associated significantly with the 5-year incidence of albuminuria (OR, 1.71; 95% CI, 1.12-2.61; P = 0.01), but not reduced eGFR (OR, 0.93; 95% CI, 0.53-1.66; P = 0.8).
  
  
  CONCLUSIONS
  The observational nature of the study does not account for unmeasured confounders. Only baseline 25(OH)D level was measured and therefore may not accurately reflect lifetime levels. Differences in baseline characteristics of participants who were included compared with those excluded due to missing data or follow-up may limit the applicability of results to the original AusDiab cohort.
  
  
  CONCLUSIONS
  Our prospective cohort study shows that vitamin D deficiency is associated with a higher annual incidence of albuminuria and reduced eGFR and independently predicts the 5-year incidence of albuminuria. These associations warrant further exploration in long-term prospective clinical trials.
authors.affiliation: Department of Nephrology, Monash Medical Centre, Melbourne, Australia. matthew.damasiewicz@monash.edu
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Damasiewicz
authors.forename: Dianna J
authors.initials: DJ
authors.lastname: Magliano
authors.forename: Robin M
authors.initials: RM
authors.lastname: Daly
authors.forename: Claudia
authors.initials: C
authors.lastname: Gagnon
authors.forename: Zhong X
authors.initials: ZX
authors.lastname: Lu
authors.forename: Ken A
authors.initials: KA
authors.lastname: Sikaris
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ebeling
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Chadban
authors.forename: Robert C
authors.initials: RC
authors.lastname: Atkins
authors.forename: Peter G
authors.initials: PG
authors.lastname: Kerr
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Shaw
authors.forename: Kevan R
authors.initials: KR
authors.lastname: Polkinghorne
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate / Q000502:physiology; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance / Q000379:methods*; D011446:Prospective Studies; D051436:Renal Insufficiency, Chronic / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood* / Q000175:diagnosis / Q000453:epidemiology*
chemical_list: D015415:Biomarkers; D014807:Vitamin D; C104450:25-hydroxyvitamin D