Department of Occupational Therapy, Tufts University Graduate School of Arts and Sciences, Medford, Massachusetts.
Department of Health Law, Policy & Management, Boston University School of Public Health, Massachusetts.
Gerontologist. 2020 Jan 24;60(1):e11-e19. doi: 10.1093/geront/gnz010.
To better understand the disablement process among older adults, improved measures of activity limitations are needed. Traditional population-level measures lack the ability to distinguish precise gradations of activity limitation and are unable to detect degrees of differences over a wide range of ability levels. Therefore, we used contemporary measurement methods to improve upon current methodologies for characterizing activity limitations within the National Health and Aging Trends Study (NHATS) .
We used the NHATS Round 1 cohort to assess the feasibility of constructing an Activity Limitations scale using Rasch item response theory methods. Factor analysis was used to develop the scale from a set of existing items in the NHATS Mobility, Self-Care, and Household Activity domains. Psychometric properties of the scale were evaluated and the scale was used to examine change in activity limitations among the sample from 2011 to 2015.
Results supported an 18-item scale (N = 7,609). Rasch infit and outfit statistics were within acceptable range for all items (Cronbach's alpha = 0.95; sample score reliability = 0.83). From 2011 to 2015, 5.88% older adults demonstrated increase in function, 15% showed decrease in function, and 78% of the sample showed no change (did not exceed ± MDC90).
Findings demonstrate that a unidimensional, interval scale of activity limitations can be constructed using traditional survey measures nested within the NHATS. Results revealed concerns regarding ceiling effects within the current self-report items of activity limitations suggesting future work is needed to expand the range of ability currently represented in the NHATS Activity Limitation items.
为了更好地了解老年人的失能过程，需要改进活动受限的测量方法。传统的人群水平测量方法缺乏区分活动受限的精确程度的能力，也无法检测广泛能力水平上的差异程度。因此，我们使用现代测量方法改进了《国家健康老龄化趋势研究》（NHATS）中用于描述活动受限的当前方法。
我们使用 NHATS 第一轮队列来评估使用 Rasch 项目反应理论方法构建活动受限量表的可行性。因子分析用于从 NHATS 移动性、自我护理和家庭活动领域的一组现有项目中开发量表。评估了量表的心理测量特性，并使用该量表检查了样本在 2011 年至 2015 年间活动受限的变化。
结果支持 18 项量表（N = 7609）。所有项目的 Rasch 内特和外特统计值均在可接受范围内（Cronbach's alpha = 0.95；样本得分可靠性 = 0.83）。从 2011 年到 2015 年，5.88%的老年人功能有所改善，15%的老年人功能下降，78%的样本没有变化（未超过±MDC90）。
研究结果表明，使用传统的嵌套在 NHATS 中的调查测量方法可以构建一个一维的、区间尺度的活动受限量表。结果显示，当前活动受限自我报告项目中存在天花板效应的问题，这表明需要进一步研究来扩大 NHATS 活动受限项目中目前所代表的能力范围。
