Rantanen T, Guralnik J M, Ferrucci L, Leveille S, Fried L P
Epidemiology, Demography and Biometry Program, National Institute on Aging, National Institutes of Health, Bethesda, Maryland, USA.
J Gerontol A Biol Sci Med Sci. 1999 Apr;54(4):M172-6. doi: 10.1093/gerona/54.4.m172.
Little information is available on the joint effects of multiple impairments (coimpairments) on the risk of disability. Our aim was to study the joint effects of strength and balance impairments on severe walking disability.
The data are from the baseline of the Women's Health and Aging Study (WHAS), a study of moderately to severely disabled women. A total of 1,002 women aged 65 and older participated in the tests, which took place in their homes. Severe walking disability was defined as self-reported inability to walk one-quarter mile and customary walking speed in a 4-meter test of < or =0.4 m/s. Balance was measured as an ability to hold progressively more difficult stands (feet side-by-side, semitandem and tandem stands). Maximal knee extension strength was measured using a hand-held dynamometer.
There were 129 women who were severely walking disabled but able to walk at least minimally. In logistic regression analysis, balance and knee extension strength were independent predictors of severe walking disability. To study the combined effects, nine groups were formed on the basis of strength tertiles by balance categories in the entire population. In the best balance category, the crude prevalences of severe walking disability were 1.2%, 4.9%, and 14.3% in the highest to lowest strength tertiles. In the middle balance category, the rates were 2.9%, 10.0%, and 45.4.1%, and in the poorest balance category 4.9%, 22.1%, and 42.6%, correspondingly. The age, body weight, and height-adjusted odds ratios (OR) showed that the risk of severe walking disability in the subgroup with best balance and strength was less than 5% of the risk in the subgroup with poorest balance and strength (OR .034, 95% confidence interval [CI] .007-.166). Correspondingly, in the subgroups with poorest strength and best balance (OR .097, 95% CI .025-.38) or poorest balance and best strength (OR .102, 95% CI .012-.866) the risk was about 10%. The age-specific estimates of prevalence of severe walking disability in women were: 2.0% for ages 65-74 years, 3.4% for ages 75-84 years, and 9.1% for ages 85 years and older.
The burden of coimpairments seems to be greater than the sum of single impairments involved. An effective way to reduce severe disabilities could be prevention of coimpairments.
关于多种功能障碍（合并功能障碍）对残疾风险的联合影响，目前所知信息较少。我们的目的是研究力量和平衡功能障碍对严重步行残疾的联合影响。
数据来自女性健康与衰老研究（WHAS）的基线，该研究针对中度至重度残疾女性。共有1002名65岁及以上的女性在家中参与了测试。严重步行残疾定义为自我报告无法行走四分之一英里，以及在4米测试中习惯步行速度小于或等于0.4米/秒。平衡能力通过保持逐渐增加难度的站立姿势（双脚并排、半前后站立和前后站立）来测量。使用手持测力计测量最大膝关节伸展力量。
有129名女性存在严重步行残疾，但至少还能进行最低限度的行走。在逻辑回归分析中，平衡能力和膝关节伸展力量是严重步行残疾的独立预测因素。为了研究联合影响，根据整个人口中按平衡类别划分的力量三分位数形成了九组。在最佳平衡类别中，最高至最低力量三分位数的严重步行残疾粗患病率分别为1.2%、4.9%和14.3%。在中等平衡类别中，患病率分别为2.9%、10.0%和45.4%，而在最差平衡类别中相应为4.9%、22.1%和42.6%。年龄、体重和身高调整后的优势比（OR）表明，平衡和力量最佳亚组中严重步行残疾的风险不到平衡和力量最差亚组风险的5%（OR 0.034，95%置信区间[CI] 0.007 - 0.166）。相应地，在力量最差但平衡最佳（OR 0.097，95% CI 0.025 - 0.38）或平衡最差但力量最佳（OR 0.102，95% CI 0.012 - 0.866）的亚组中，风险约为10%。按年龄划分的女性严重步行残疾患病率估计值为：65 - 74岁为2.0%，75 - 84岁为3.4%，85岁及以上为9.1%。
合并功能障碍的负担似乎大于单个功能障碍负担的总和。预防合并功能障碍可能是减少严重残疾的有效方法。
