Rantanen T, Guralnik J M, Ferrucci L, Penninx B W, Leveille S, Sipilä S, Fried L P
Epidemiology, Demography and Biometry Program, National Institute of Aging, National Institutes of Health, Bethesda, Maryland, USA.
J Am Geriatr Soc. 2001 Jan;49(1):21-7. doi: 10.1046/j.1532-5415.2001.49005.x.
Severe disabilities are common among older people who have impairments in a range of physiologic systems. It is not known, however, whether the presence of multiple impairments, or coimpairments, is associated with increased risk of developing new disability. The aim of this study was to determine the combined effects of two impairments, decreased knee-extension strength and poor standing balance, on the risk of developing severe walking disability among older, moderately-to-severely disabled women who did not have severe walking disability at baseline.
The Women's Health and Aging Study is a 3-year prospective study with 6 semi-annual follow-up data-collection rounds following the baseline.
At baseline, knee-extension strength and standing balance tests took place in the participants' homes.
758 women who were not severely walking disabled at baseline.
Severe walking disability was defined as customary walking speed of < 0.4 meters/second and inability to walk one quarter of a mile, or being unable to walk.
Over the course of the study, 173 women became severely disabled in walking. The cumulative incidence of severe walking disability from the first to the sixth follow-up was: 7.8%, 12.0%, 15.1% 19.5% 21.2%, and 22.8%. In Cox proportional hazards models, both strength and balance were significant predictors of new walking disability. In the best balance category, the rates of developing severe walking disability expressed per 100 person years were 3.1, 6.1, and 5.3 in the highest- to lowest-strength tertiles. In the middle balance category, the rates were 9.6, 13.2, and 14.7, and in the poorest balance category 21.6, 12.7, and 37.1, correspondingly. The relative risk (RR) of onset of severe walking disability adjusted for age, height, weight, and race was more than five times greater in the group with poorest balance and strength (RR 5.12, 95% confidence limit [95% CI] 2.68-9.80) compared with the group with best balance and strength (the reference group). Among those who had poorest balance and best strength, the RR of severe walking disability was 3.08 (95% CI 1.33-7.14). Among those with best balance and poorest strength, the RR was 0.97 (95% CI 0.49-1.93), as compared with the reference group.
The presence of coimpairments is a powerful predictor of new, severe walking disability, an underlying cause of dependence in older people. Substantial reduction in the risk of walking disability could be achieved even if interventions were successful in correcting only one of the impairments because a deficit in only one physiologic system may be compensated for by good capacity in another system.
严重残疾在一系列生理系统存在损伤的老年人中很常见。然而，尚不清楚多种损伤（即合并损伤）的存在是否与新发残疾风险增加相关。本研究的目的是确定两种损伤——膝关节伸展力量下降和站立平衡能力差——对基线时无严重步行残疾的老年中重度残疾女性发生严重步行残疾风险的综合影响。
女性健康与衰老研究是一项为期3年的前瞻性研究，基线后有6次半年期随访数据收集轮次。
基线时，在参与者家中进行膝关节伸展力量和站立平衡测试。
758名基线时无严重步行残疾的女性。
严重步行残疾定义为习惯步行速度<0.4米/秒、无法行走四分之一英里或无法行走。
在研究过程中，173名女性出现严重步行残疾。从第一次随访到第六次随访，严重步行残疾的累积发病率分别为：7.8%、12.0%、15.1%、19.5%、21.2%和22.8%。在Cox比例风险模型中，力量和平衡都是新发步行残疾的显著预测因素。在平衡状况最佳的类别中，每100人年发生严重步行残疾的发生率在力量最高三分位数到最低三分位数中分别为3.1、6.1和5.3。在平衡状况中等的类别中，发生率分别为9.6、13.2和14.7，而在平衡状况最差的类别中分别为21.6、12.7和37.1。调整年龄、身高、体重和种族后，平衡和力量最差组发生严重步行残疾的相对风险（RR）比平衡和力量最佳组（参照组）高五倍多（RR 5.12，95%置信区间[95%CI]2.68 - 9.80）。在平衡最差但力量最佳的人群中，严重步行残疾的RR为3.08（CI 1.33 - 7.14）。与参照组相比，在平衡最佳但力量最差的人群中，RR为0.97（95%CI 0.49 - 1.93）。
合并损伤的存在是新发严重步行残疾的有力预测因素，而严重步行残疾是老年人依赖他人的一个根本原因。即使干预措施仅成功纠正其中一种损伤，也可大幅降低步行残疾风险，因为仅一个生理系统的缺陷可能会被另一个系统的良好功能所补偿。
