Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA.
Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD, USA.
Am J Clin Nutr. 2021 Jul 1;114(1):16-28. doi: 10.1093/ajcn/nqab025.
Threshold serum 25-hydroxyvitamin D [25(OH)D] concentrations for extraskeletal outcomes are uncertain and could differ from recommendations (20-30 ng/mL) for skeletal health.
We aimed to identify and validate sex-specific threshold 25(OH)D concentrations for older adults' physical function.
Using 5 large prospective, population-based studies-Age, Gene/Environment Susceptibility-Reykjavik (n = 4858, Iceland); Health, Aging, and Body Composition (n = 2494, United States); Invecchiare in Chianti (n = 873, Italy); Osteoporotic Fractures in Men (n = 2301, United States); and Study of Osteoporotic Fractures (n = 5862, United States)-we assessed 16,388 community-dwelling adults (10,376 women, 6012 men) aged ≥65 y. We analyzed 25(OH)D concentrations with the primary outcome (incident slow gait: women <0.8 m/s; men <0.825 m/s) and secondary outcomes (gait speed, incident self-reported mobility, and stair climb impairment) at median 3.0-y follow-up. We identified sex-specific 25(OH)D thresholds that best discriminated incident slow gait using machine learning in training data (2/3 cohort-stratified random sample) and validated using the remaining (validation) data and secondary outcomes.
Mean age in the cohorts ranged from 74.4 to 76.5 y in women and from 73.3 to 76.6 y in men. Overall, 1112/6123 women (18.2%) and 494/3937 men (12.5%) experienced incident slow gait, 1098/7011 women (15.7%) and 474/3962 men (12.0%) experienced incident mobility impairment, and 1044/6941 women (15.0%) and 432/3993 men (10.8%) experienced incident stair climb impairment. Slow gait was best discriminated by 25(OH)D <24.0 ng/mL compared with 25(OH)D ≥24.0 ng/mL in women (RR: 1.29; 95% CI: 1.10, 1.50) and 25(OH)D <21.0 ng/mL compared with 25(OH)D ≥21.0 ng/mL in men (RR: 1.43; 95% CI: 1.01, 2.02). Most associations between 25(OH)D and secondary outcomes were modest; estimates were similar between validation and training datasets.
Empirically identified and validated sex-specific threshold 25(OH)D concentrations for physical function for older adults, 24.0 ng/mL for women and 21.0 ng/mL for men, may inform candidate reference concentrations or the design of vitamin D intervention trials.
骨骼健康推荐的血清 25- 羟维生素 D [25(OH)D] 浓度阈值为 20-30ng/mL，而用于骨骼外结局的阈值浓度尚不确定，可能有所不同。
我们旨在确定并验证适用于老年人体能的性别特异性 25(OH)D 浓度阈值。
我们使用了 5 项大型前瞻性、基于人群的研究——年龄、基因/环境易感性-雷克雅未克研究（n=4858，冰岛）；健康、老龄化和身体成分研究（n=2494，美国）；因斯布鲁克-基亚尼研究（n=873，意大利）；男性骨质疏松性骨折研究（n=2301，美国）；和骨质疏松性骨折研究（n=5862，美国）——评估了 16388 名居住在社区的成年人（女性 10376 名，男性 6012 名），年龄≥65 岁。我们分析了 25(OH)D 浓度与主要结局（女性<0.8m/s；男性<0.825m/s 的新发慢步）和次要结局（步行速度、新发自我报告的活动能力和爬楼梯能力受损）之间的关系，中位随访时间为 3.0 年。我们使用机器学习在训练数据（2/3 队列分层随机样本）中确定了最佳区分新发慢步的性别特异性 25(OH)D 阈值，并使用剩余（验证）数据和次要结局对其进行了验证。
队列中的平均年龄在女性中为 74.4-76.5 岁，在男性中为 73.3-76.6 岁。总体而言，1112/6123 名女性（18.2%）和 494/3937 名男性（12.5%）发生了新发慢步，1098/7011 名女性（15.7%）和 474/3962 名男性（12.0%）发生了活动能力受损，1044/6941 名女性（15.0%）和 432/3993 名男性（10.8%）发生了爬楼梯能力受损。与 25(OH)D≥24.0ng/mL 相比，25(OH)D<24.0ng/mL 能更好地区分女性的慢步（RR：1.29；95%CI：1.10，1.50），与 25(OH)D≥21.0ng/mL 相比，25(OH)D<21.0ng/mL 能更好地区分男性的慢步（RR：1.43；95%CI：1.01，2.02）。25(OH)D 与次要结局之间的大多数关联都较弱；验证数据集和训练数据集的估计值相似。
我们通过实证方法确定并验证了适用于老年人体能的性别特异性 25(OH)D 浓度阈值，女性为 24.0ng/mL，男性为 21.0ng/mL，这可能为候选参考浓度或维生素 D 干预试验的设计提供信息。
