title: Serum 25-hydroxyvitamin D level and kidney function decline in a Swiss general adult population.
abstract: OBJECTIVE
  Molecular evidence suggests that levels of vitamin D are associated with kidney function loss. Still, population-based studies are limited and few have considered the potential confounding effect of baseline kidney function. This study evaluated the association of serum 25-hydroxyvitamin D with change in eGFR, rapid eGFR decline, and incidence of CKD and albuminuria.
  
  
  METHODS
  Baseline (2003-2006) and 5.5-year follow-up data from a Swiss adult general population were used to evaluate the association of serum 25-hydroxyvitamin D with change in eGFR, rapid eGFR decline (annual loss >3 ml/min per 1.73 m(2)), and incidence of CKD and albuminuria. Serum 25-hydroxyvitamin D was measured at baseline using liquid chromatography-tandem mass spectrometry. eGFR and albuminuria were collected at baseline and follow-up. Multivariate linear and logistic regression models were used considering potential confounding factors.
  
  
  RESULTS
  Among the 4280 people included in the analysis, the mean±SD annual eGFR change was -0.57±1.78 ml/min per 1.73 m(2), and 287 (6.7%) participants presented rapid eGFR decline. Before adjustment for baseline eGFR, baseline 25-hydroxyvitamin D level was associated with both mean annual eGFR change and risk of rapid eGFR decline, independently of baseline albuminuria. Once adjusted for baseline eGFR, associations were no longer significant. For every 10 ng/ml higher baseline 25-hydroxyvitamin D, the adjusted mean annual eGFR change was -0.005 ml/min per 1.73 m(2) (95% confidence interval, -0.063 to 0.053; P=0.87) and the risk of rapid eGFR decline was null (odds ratio, 0.93; 95% confidence interval, 0.79 to 1.08; P=0.33). Baseline 25-hydroxyvitamin D level was not associated with incidence of CKD or albuminuria.
  
  
  CONCLUSIONS
  The association of 25-hydroxyvitamin D with eGFR decline is confounded by baseline eGFR. Sufficient 25-hydroxyvitamin D levels do not seem to protect from eGFR decline independently from baseline eGFR.
authors.affiliation: Division of Chronic Diseases, Institute of Social and Preventive Medicine, Unit of Population Epidemiology, Division of Primary Care Medicine, Department of Community Medicine, Primary Care and Emergency Medicine, Geneva University Hospitals, Geneva, Switzerland; and Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, Georgia Idris.Guessous@chuv.ch.
authors.forename: Idris
authors.initials: I
authors.lastname: Guessous
authors.affiliation: Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, Georgia.
authors.forename: William
authors.initials: W
authors.lastname: McClellan
authors.affiliation: Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, Georgia.
authors.forename: David
authors.initials: D
authors.lastname: Kleinbaum
authors.affiliation: Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, Georgia.
authors.forename: Viola
authors.initials: V
authors.lastname: Vaccarino
authors.affiliation: Service of Biomedicine.
authors.forename: Henry
authors.initials: H
authors.lastname: Hugues
authors.affiliation: Service of Biomedicine.
authors.forename: Olivier
authors.initials: O
authors.lastname: Boulat
authors.affiliation: Division of Chronic Diseases, Institute of Social and Preventive Medicine, Department of Internal Medicine, University Hospital Center, Lausanne, Switzerland;
authors.forename: Pedro
authors.initials: P
authors.lastname: Marques-Vidal
authors.affiliation: Division of Chronic Diseases, Institute of Social and Preventive Medicine.
authors.forename: Fred
authors.initials: F
authors.lastname: Paccaud
authors.affiliation: Unit of Population Epidemiology, Division of Primary Care Medicine, Department of Community Medicine, Primary Care and Emergency Medicine, Geneva University Hospitals, Geneva, Switzerland; and.
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Theler
authors.affiliation: Unit of Population Epidemiology, Division of Primary Care Medicine, Department of Community Medicine, Primary Care and Emergency Medicine, Geneva University Hospitals, Geneva, Switzerland; and.
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Gaspoz
authors.affiliation: Service of Nephrology, and.
authors.forename: Michel
authors.initials: M
authors.lastname: Burnier
authors.affiliation: Department of Internal Medicine, University Hospital Center, Lausanne, Switzerland;
authors.forename: Gérard
authors.initials: G
authors.lastname: Waeber
authors.affiliation: Department of Internal Medicine, University Hospital Center, Lausanne, Switzerland;
authors.forename: Peter
authors.initials: P
authors.lastname: Vollenweider
authors.affiliation: Division of Chronic Diseases, Institute of Social and Preventive Medicine.
authors.forename: Murielle
authors.initials: M
authors.lastname: Bochud
mesh_terms: D000328:Adult; D000368:Aged; D000419:Albuminuria / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D015415:Biomarkers / Q000097:blood; D002853:Chromatography, Liquid; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D015994:Incidence; D007668:Kidney / Q000503:physiopathology*; D016014:Linear Models; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011159:Population Surveillance; D015995:Prevalence; D011379:Prognosis; D065840:Protective Factors; D051436:Renal Insufficiency, Chronic / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D018570:Risk Assessment; D012307:Risk Factors; D013557:Switzerland / Q000453:epidemiology; D053719:Tandem Mass Spectrometry; D013997:Time Factors; 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
keywords: chronic kidney disease; epidemiology and outcomes; glomerular filtration rate; renal function decline; vitamin D