title: Associations of serum 25-hydroxyvitamin D concentrations with quality of life and self-rated health in an older population.
abstract: BACKGROUND
  Vitamin D deficiency has been associated with impaired physical functioning, depression, and several chronic diseases and might thereby affect quality of life and self-rated health.
  
  
  OBJECTIVE
  The aim of this study was to assess relationships of serum 25-hydroxyvitamin D [25(OH)D] with quality of life and self-rated health and to examine whether physical performance, depressive symptoms, and number of chronic diseases mediate these relationships.
  
  
  METHODS
  We analyzed data from the Longitudinal Aging Study Amsterdam, an ongoing population-based cohort study of older Dutch individuals.
  
  
  METHODS
  Serum 25(OH)D was classified into the following categories: less than 25, 25-50, and 50 nmol/L or greater. We assessed quality of life (QOL) using the Short Form-12 Health Survey (SF-12; n = 862) and self-rated health (SRH) with a single question, dichotomized into good vs poor SRH (n = 1248).
  
  
  RESULTS
  Individuals with serum 25(OH)D less than 25 nmol/L scored lower on the physical component score of the SF-12 and had a lower odds on good SRH score compared with individuals with serum 25(OH)D greater than 50 nmol/L (β (95% confidence interval) -3.9 (-6.5 to -1.3) for SF-12, and odds ratio [95% confidence interval) 0.50 (0.33-0.76) for SRH]. Physical performance, depressive symptoms, and the number of chronic diseases were associated with vitamin D status, QOL, and SRH. Adding all these potential mediators to regression models attenuated associations of 25(OH)D less than 25 nmol/L with QOL with 78% and SRH with 32%.
  
  
  CONCLUSIONS
  Lower 25(OH)D status is related to lower scores on QOL and SRH. A large part of the association with QOL can statistically be explained by physical performance, depressive symptoms, and the number of chronic diseases.
authors.affiliation: Department of Internal Medicine and Endocrinology (R.R., P.L., R.T.d.J.), VU University Medical Center, and Department of Epidemiology and Biostatistics (K.M.A.S., N.M.v.S., D.J.D., P.L.), EMGO Institute for Health and Care Research, VU University Medical Center, VU University Medical Center, 1081 BT Amsterdam, The Netherlands.
authors.forename: R
authors.initials: R
authors.lastname: Rafiq
authors.forename: K M A
authors.initials: KM
authors.lastname: Swart
authors.forename: N M
authors.initials: NM
authors.lastname: van Schoor
authors.forename: D J
authors.initials: DJ
authors.lastname: Deeg
authors.forename: P
authors.initials: P
authors.lastname: Lips
authors.forename: R T
authors.initials: RT
authors.lastname: de Jongh
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood*; D015331:Cohort Studies; D003863:Depression / Q000453:epidemiology; D005260:Female; D006304:Health Status; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009043:Motor Activity; D009426:Netherlands / Q000453:epidemiology; D016017:Odds Ratio; D015995:Prevalence; D011788:Quality of Life; D012044:Regression Analysis; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood* / Q000453:epidemiology*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D