title: Vitamin D deficiency, self-reported physical activity and health-related quality of life: the Comprehensive Dialysis Study.
abstract: BACKGROUND
  As research has identified a wide array of biological functions of vitamin D, the consequences of vitamin D deficiency in persons with chronic kidney disease has attracted increased attention. The objective of this study was to determine the extent of 25-hydroxyvitamin D (25-OH vitamin D) deficiency and its associations with self-reported physical activity and health-related quality of life (HRQoL) among participants of the Comprehensive Dialysis Study (CDS).
  
  
  METHODS
  The nutrition substudy of the CDS enrolled patients new to dialysis from 68 dialysis units throughout the USA. Baseline 25-OH vitamin D concentration was measured using the Direct Enzyme Immunoassay (Immunodiagnostic Systems Inc.). Physical activity was measured with the Human Activity Profile (HAP); the Medical Outcomes Study Short Form-12 (SF-12) was employed to measure HRQoL.
  
  
  RESULTS
  Mean age of the participants (n = 192) was 62 years. There were 124 participants (65%) with 25-OH vitamin D concentrations < 15 ng/mL, indicating deficiency, and 64 (33%) with 25-OH vitamin D ≥ 15 to <30 ng/mL, indicating insufficiency. After adjusting for age, sex, race/ethnicity, diabetes, season and center, lower 25-OH vitamin D concentrations were independently associated with lower scores on the HAP and on the Mental Component Summary of the SF-12 (P < 0.05 for both), but not with the Physical Component Summary of the SF-12.
  
  
  CONCLUSIONS
  In a well-characterized cohort of incident dialysis patients, lower 25-OH vitamin D concentrations were associated with lower self-reported physical activity and poorer self-reported mental health.
authors: Division of Nephrology, Department of Medicine, Stanford University School of Medicine, Palo Alto, CA, USA. sanand2@stanford.edu
authors: Shuchi
authors: S
authors: Anand
authors: George A
authors: GA
authors: Kaysen
authors: Glenn M
authors: GM
authors: Chertow
authors: Kirsten L
authors: KL
authors: Johansen
authors: Barbara
authors: B
authors: Grimes
authors: Lorien S
authors: LS
authors: Dalrymple
authors: Manjula
authors: M
authors: Kurella Tamura
mesh_terms: D015444:Exercise; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood / Q000150:complications* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011788:Quality of Life; D006435:Renal Dialysis / Q000009:adverse effects*; D057566:Self Report; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000209:etiology*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D