Department of Geriatric Medicine, Nepean Hospital, Penrith, NSW, Australia 2751.
J Nutr Health Aging. 2012 Mar;16(3):270-5. doi: 10.1007/s12603-011-0345-5.
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.
Cross-sectional study.
Falls and Fractures Clinic, Department of Geriatric Medicine, Nepean Hospital, Penrith, Australia.
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.
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.
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.
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.
姿势不稳（PI）是跌倒的一个重要危险因素，尤其是在体弱的老年人群中。本研究旨在探讨维生素 D 缺乏对社区居住的老年受试者 PI 的影响。我们的目的是确定维生素 D 缺乏与老年跌倒者 PI 之间的潜在关联。
横断面研究。
澳大利亚彭里斯尼平医院老年医学科跌倒和骨折诊所。
145 名年龄在 65 岁及以上、在评估前 6 个月内至少发生过一次跌倒的成年人。
在基线时测定血清 25（OH）维生素 D3 [25（OH）D3]和甲状旁腺激素浓度。根据血清 25（OH）D3 水平将受试者分为 3 组，以下列截断值：<30nmol/L（缺乏）、30-50nmol/L（不足）和>50nmol/L（正常）。其他基线测量包括体重指数、微型营养评估、握力、血清钙浓度和肌酐清除率，这些都被用作协变量。使用 Medicaa（乌拉圭）的计算机虚拟现实系统评估 PI。测量参数包括闭眼在泡沫上的稳定性极限（LOS）和中心压力（COP）（ECF）和视动刺激。从闭眼站在泡沫上的置信椭圆（ECF）中计算出的估计摆动面积也用作 PI 参数。使用 GaitRITE 步道系统测量步态速度（GV）。
维生素 D 缺乏（<30nmol/L）时姿势受损，表现为 LOS 降低（90±18），ECF 升高（25±10）和 GV 减慢（55±7），与不足和正常组相比。在调整人口统计学、生化和人体测量学变量后，维生素 D 缺乏与 ECF 下的 LOS 降低和 COP 升高显著相关。
低水平的维生素 D 与 PI 有关。这种关联也可能对缓慢的 GV 和跌倒风险增加产生影响。总之，我们使用一种客观的方法来测量老年跌倒者的平衡，发现了维生素 D 在平衡控制中的新作用。需要前瞻性研究来证实维生素 D 对 PI 的影响，并阐明这种关联的机制。
