title: Non-linear associations between serum 25-OH vitamin D and indices of arterial stiffness and arteriosclerosis in an older population.
abstract: BACKGROUND
  several studies have been pointing towards a non-linear relationship between serum 25(OH)D and cardiovascular disease. Next to vitamin D deficiency, also higher levels of 25(OH)D have been reported to be associated with increased cardiovascular risk. We aimed to investigate the nature of the relationship between serum 25(OH)D and measures of arterial stiffness and arteriosclerosis in an elderly population.
  
  
  METHODS
  cross-sectional.
  
  
  METHODS
  a subgroup of the B-PROOF study was included to determine associations between serum 25(OH)D and arterial stiffness and atherosclerosis (n = 567, 57% male, age 72.6 ± 5.6 years, mean serum 25(OH)D 54.6 ± 24.1 nmol/l).
  
  
  METHODS
  carotid intima media thickness (IMT) was assessed using ultrasonography and pulse wave velocity (PWV) was determined with applanation tonometry. Associations were tested using multivariable restricted cubic spline functions and stratified linear regression analysis.
  
  
  RESULTS
  the associations between serum 25(OH)D and carotid IMT or PWV were non-linear. Spline functions demonstrated a difference between 25(OH)D deficient and sufficient individuals. In serum 25(OH)D sufficient participants (≥50 nmol/l; n = 287), a positive association with IMT and serum 25(OH)D was present (β 1.24; 95%CI [0.002; 2.473]). PWV levels were slightly lower in vitamin D deficient individuals, but the association with 25(OH)D was not significant.
  
  
  CONCLUSIONS
  our study demonstrates that associations of serum 25(OH)D and PWV and IMT in an elderly population are not linear. In particular from serum 25(OH)D levels of 50 nmol/l and up, there is a slight increase of IMT with increasing 25(OH)D levels.
authors.affiliation: Department of Geriatrics, Erasmus MC,'s Gravendijkwal 230, Rotterdam 3015 CE, The Netherlands.
authors.forename: Suzanne C
authors.initials: SC
authors.lastname: van Dijk
authors.affiliation: Department of Epidemiology and Biostatistics, EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Evelien
authors.initials: E
authors.lastname: Sohl
authors.affiliation: Department of Internal Medicine, Section of Geriatrics, Erasmus MC, PO Box 2040, Rotterdam 3000 CA, The Netherlands.
authors.forename: Christian
authors.initials: C
authors.lastname: Oudshoorn
authors.affiliation: Department of Internal Medicine, Section of Geriatrics, Erasmus MC, PO Box 2040, Rotterdam 3000 CA, The Netherlands.
authors.forename: Anke W
authors.initials: AW
authors.lastname: Enneman
authors.affiliation: Department of Internal Medicine, Section of Geriatrics, Erasmus MC, PO Box 2040, Rotterdam 3000 CA, The Netherlands.
authors.forename: Annelies C
authors.initials: AC
authors.lastname: Ham
authors.affiliation: Department of Epidemiology and Biostatistics, EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Karin M A
authors.initials: KM
authors.lastname: Swart
authors.affiliation: Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.
authors.forename: Janneke P
authors.initials: JP
authors.lastname: van Wijngaarden
authors.affiliation: Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.
authors.forename: Elske M
authors.initials: EM
authors.lastname: Brouwer-Brolsma
authors.affiliation: Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.
authors.forename: Nikita L
authors.initials: NL
authors.lastname: van der Zwaluw
authors.affiliation: Department of Internal Medicine, Erasmus MC, Rotterdam, The Netherlands Netherlands Consortium for Healthy Aging, Rotterdam, Leiden, The Netherlands.
authors.forename: Andre G
authors.initials: AG
authors.lastname: Uitterlinden
authors.affiliation: Wageningen University, Wageningen, The Netherlands.
authors.forename: Lisette C P G M
authors.initials: LC
authors.lastname: de Groot
authors.affiliation: Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.
authors.forename: Rosalie A M
authors.initials: RA
authors.lastname: Dhonukshe-Rutten
authors.affiliation: Department of Internal Medicine, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Paul
authors.initials: P
authors.lastname: Lips
authors.affiliation: Department of Epidemiology and Biostatistics, EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Natasja M
authors.initials: NM
authors.lastname: van Schoor
authors.affiliation: Department of Clinical Chemistry, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Henk J
authors.initials: HJ
authors.lastname: Blom
authors.affiliation: Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.
authors.forename: Johanna M
authors.initials: JM
authors.lastname: Geleijnse
authors.affiliation: Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.
authors.forename: Edith J
authors.initials: EJ
authors.lastname: Feskens
authors.affiliation: Department of Internal Medicine, VU University Medical Center, Amsterdam, The Netherlands Institute for Cardiovascular Research ICaR-VU, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Yvo M
authors.initials: YM
authors.lastname: Smulders
authors.affiliation: Department of Geriatrics, Erasmus MC,'s Gravendijkwal 230, Rotterdam 3015 CE, The Netherlands Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: M Carola
authors.initials: MC
authors.lastname: Zillikens
authors.affiliation: Department of Epidemiology and Biostatistics, EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands Department of Internal Medicine, Endocrine Section & EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Renate T
authors.initials: RT
authors.lastname: de Jongh
authors.affiliation: Department of Vascular Medicine, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Anton H
authors.initials: AH
authors.lastname: van den Meiracker
authors.affiliation: Department of Geriatric Medicine, Erasmus MC, PO Box 2040, Rotterdam 3000 CA, The Netherlands.
authors.forename: Francesco U S
authors.initials: FU
authors.lastname: Mattace Raso
authors.affiliation: Department of Internal Medicine, Section of Geriatrics, Erasmus MC, PO Box 2040, Rotterdam 3000 CA, The Netherlands.
authors.forename: Nathalie
authors.initials: N
authors.lastname: van der Velde
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood; D001161:Arteriosclerosis / Q000097:blood / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D015415:Biomarkers / Q000097:blood; D059168:Carotid Intima-Media Thickness; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008365:Manometry; D015999:Multivariate Analysis; D017711:Nonlinear Dynamics; D063177:Pulse Wave Analysis; D012307:Risk Factors; D059289:Vascular Stiffness; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D015415:Biomarkers; D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: arterial stiffness; arteriosclerosis; non-linear associations; older people; serum 25-OH vitamin D