About this Journal Submit a Manuscript Table of Contents
Journal of Aging Research
Volume 2013 (2013), Article ID 751310, 6 pages
http://dx.doi.org/10.1155/2013/751310
Clinical Study

The Association between Seasonal Variation in Vitamin D, Postural Sway, and Falls Risk: An Observational Cohort Study

1School of Human Life Sciences, University of Tasmania, Launceston, TAS 7250, Australia
2School of Physiotherapy, Curtin University, Perth, WA 6845, Australia

Received 28 May 2013; Revised 12 August 2013; Accepted 27 August 2013

Academic Editor: Alice Nieuwboer

Copyright © 2013 Marie-Louise Bird et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Introduction. Low serum vitamin D levels are associated with increased postural sway. Vitamin D varies seasonally. This study investigates whether postural sway varies seasonally and is associated with serum vitamin D and falls. Methods. In a longitudinal observational study, eighty-eight independently mobile community-dwelling older adults (69.7 7.6 years) were evaluated on five occasions over one year, measuring postural sway (force platform), vitamin D levels, fall incidence, and causes and adverse outcomes. Mixed-methods Poisson regression was used to determine associations between measures. Results. Postural sway did not vary over the year. Vitamin D levels varied seasonally ( ), peaking in summer. Incidence of falls ( ) and injurious falls ( ) were lower in spring, with the highest fall rate at the end of autumn. Postural sway was not related to vitamin D ( ) or fall rates, but it was associated with fall injuries (IRR 1.59 (CI 1.14 to 2.24, ). Conclusions. Postural sway remained stable across the year while vitamin D varied seasonally. Participants with high values for postural sway demonstrated higher rates of injurious falls. This study provides important evidence for clinicians and researchers providing interventions measuring balance outcomes across seasons.