title: Mortality rates across 25-hydroxyvitamin D (25[OH]D) levels among adults with and without estimated glomerular filtration rate <60 ml/min/1.73 m2: the third national health and nutrition examination survey.
abstract: BACKGROUND
  Previous studies exploring the association between 25[OH]D levels and mortality in adults with and without kidney disease utilized 25[OH]D thresholds that have recently been scrutinized by the Institute of Medicine Committee to Review Dietary References Intakes for Vitamin D and Calcium.
  
  
  OBJECTIVE
  We explored all-cause mortality rates across the spectrum of 25[OH]D levels over an eighteen-year follow-up among adults with and without an estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m(2).
  
  
  METHODS
  The study included 1,097 U.S. adults with eGFR <60 ml/min/1.73 m(2) and 14, 002 adults with eGFR ≥60 ml/min/1.73 m(2). Mortality rates and rate ratios (RR) across 25[OH]D groups were calculated with Poisson regression and restricted cubic splines while adjusting for covariates.
  
  
  RESULTS
  Prevalence of 25[OH]D levels <30 and <20 ng/ml among adults with eGFR <60 ml/min/1.73 m(2) was 76.5% (population estimate 6.2 million) and 35.4% (population estimate 2.9 million), respectively. Among adults with eGFR ≥ 60 ml/min/1.73 m(2), 70.5% had 25[OH]D levels <30 ng/ml (population estimate 132.2 million) while 30.3% had 25[OH]D levels <20 ng/ml (population estimate 56.8 million). Significantly higher mortality rates were noted among individuals with 25[OH]D levels <12 ng/ml compared to referent group (24 to <30 ng/ml): RR1.41 (95% CI 1.17, 1.71) among individuals with eGFR <60 ml/min/1.73 m(2) and RR 1.32 (95% CI 1.13, 1.56) among individuals with eGFR ≥ 60 ml/min/1.73 m(2) after adjustment for covariates including co-morbid conditions. Mortality rates were fairly similar across all 25[OH]D groups with levels >20 ng/ml after adjustment for all covariates.
  
  
  CONCLUSIONS
  Regardless of presence of eGFR <60 ml/min/1.73 m(2), mortality rates across groups with 25[OH]D levels 20-40 ng/ml are similar.
authors.affiliation: Department of Preventive Medicine and Epidemiology, Loyola University Medical Center, Maywood, Illinois, United States of America. hkramer@lumc.edu
authors.forename: Holly
authors.initials: H
authors.lastname: Kramer
authors.forename: Chris
authors.initials: C
authors.lastname: Sempos
authors.forename: Guichan
authors.initials: G
authors.lastname: Cao
authors.forename: Amy
authors.initials: A
authors.lastname: Luke
authors.forename: David
authors.initials: D
authors.lastname: Shoham
authors.forename: Richard
authors.initials: R
authors.lastname: Cooper
authors.forename: Ramon
authors.initials: R
authors.lastname: Durazo-Arvizu
mesh_terms: D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D007674:Kidney Diseases / Q000097:blood* / Q000401:mortality*; D008297:Male; D009749:Nutrition Surveys; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D