title: Vitamin D status in relation to postural stability in the elderly.
abstract: OBJECTIVE
  Postural instability (PI) is an important risk factor for falls, especially in the frail older population. In this study, we investigated the impact of vitamin D deficiency on PI in a sample of community dwelling older subjects. Our objective was to determine the potential association between vitamin D deficiency and PI in older fallers.
  
  
  METHODS
  Cross-sectional study.
  
  
  METHODS
  Falls and Fractures Clinic, Department of Geriatric Medicine, Nepean Hospital, Penrith, Australia.
  
  
  METHODS
  One hundred and forty-five adults aged 65 years and older who have had at least one episode of a fall within the six months prior to assessment at the Falls and Fractures Clinic.
  
  
  METHODS
  Serum 25(OH) vitamin D3 [25(OH)D3] and parathyroid hormone concentrations were determined at baseline. Subjects were separated into 3 groups based on serum 25(OH)D3 levels with the following cut-off values: < 30 nmol/L (deficient), 30-50 nmol/L (insufficient) and > 50 nmol/L (normal). Other baseline measurements included body mass index, mini-nutritional assessment, grip strength, serum calcium concentration and creatinine clearance, which were used as covariables. PI was assessed using a computerized virtual reality system (Medicaa, Uruguay). Measured parameters included limits of stability (LOS) and centre of pressure (COP) under eyes closed on foam (ECF) and visio-vestibular stimulation. The estimated swaying area, computed from the ellipse of confidence under eyes closed standing on foam (ECF), was also used as a PI parameter. Gait velocity (GV) was measured using a GaitRITE walkway system.
  
  
  RESULTS
  Posture was impaired in vitamin D deficiency (<30 nmol/L) as indicated by lower LOS (90 +/- 18), higher ECF (25 +/- 10) and slower GV (55 +/- 7) as compared with the insufficient and normal groups. After adjustment for demographic, biochemical and anthropometric variables, vitamin D deficiency significantly correlated with low LOS and high COP under ECF.
  
  
  CONCLUSIONS
  Low levels of vitamin D were associated with PI. This association could also have an effect on slow GV and increased risk of falls. In conclusion, using an objective method to measure balance in older fallers we have identified a novel role of vitamin D in balance control. Prospective studies are required to confirm the effect of vitamin D on PI and elucidate the mechanisms of this association.
authors.affiliation: Department of Geriatric Medicine, Nepean Hospital, Penrith, NSW, Australia 2751.
authors.forename: D
authors.initials: D
authors.lastname: Boersma
authors.forename: O
authors.initials: O
authors.lastname: Demontiero
authors.forename: Z
authors.initials: Z
authors.lastname: Mohtasham Amiri
authors.forename: S
authors.initials: S
authors.lastname: Hassan
authors.forename: H
authors.initials: H
authors.lastname: Suarez
authors.forename: D
authors.initials: D
authors.lastname: Geisinger
authors.forename: P
authors.initials: P
authors.lastname: Suriyaarachchi
authors.forename: A
authors.initials: A
authors.lastname: Sharma
authors.forename: G
authors.initials: G
authors.lastname: Duque
mesh_terms: D000058:Accidental Falls / Q000517:prevention & control / Q000706:statistics & numerical data; D000368:Aged; D001315:Australia; D003430:Cross-Sectional Studies; D005260:Female; D005684:Gait / Q000502:physiology; D015577:Geriatric Assessment; D006801:Humans; D008297:Male; D009043:Motor Activity / Q000502:physiology; D053580:Muscle Strength / Q000502:physiology; D015596:Nutrition Assessment; D009752:Nutritional Status; D010281:Parathyroid Hormone / Q000097:blood; D011187:Posture / Q000502:physiology*; D012307:Risk Factors; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood / Q000150:complications*
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D