NHMRC Centre for Research Excellence in Stroke Rehabilitation and Brain Recovery, Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Australia.
Eastern Health and Eastern Health Clinical School, Monash University, Clayton, Australia.
Int J Stroke. 2020 Apr;15(3):268-277. doi: 10.1177/1747493019830583. Epub 2019 Feb 12.
The utility-weighted modified Rankin Scale (UW-mRS) is an outcome measure recently proposed to improve statistical efficiency and interpretability of the mRS. Statistical properties of the UW-mRS have been well investigated, but construct validity has yet to be established.
To investigate the construct validity of the UW-mRS as a primary outcome measure by assessing variability in utility values within and between mRS categories, over time post-stroke, and by different derivation methods.
UW-mRS was derived using assessment of quality of life (AQoL-4D) and mRS scores at 3 and 12 months ( = 2030) from a large randomized controlled trial, A Very Early Rehabilitation Trial (AVERT). Receiver operator characteristic (ROC) analysis of AQoL-4D was conducted to differentiate between sequential mRS categories. Intraclass correlation was used to explore variability in utility values over time post-stroke, UW-mRS values, and derivation methods from multiple studies.
UW-mRS values for mRS categories 0-6 at three months were 0.80, 0.78, 0.63, 0.37, 0.11, 0.03, and 0. Based on AQoL-4D utility values, areas under the ROC curve varied from 0.54 to 0.87. Time post-stroke explained 42%-56% of variability in AQoL-4D utility values in patients with no change in mRS between 3 and 12 months. The choice of the derivation method contributed to 25% of the variability in UW-mRS values.
The high variability in utility values between and within mRS categories, over time post-stroke, and using different derivation methods is not adequately reflected in the UW-mRS. These threats to construct validity warrant caution when using UW-mRS as a primary outcome measure.
Australian New Zealand Clinical Trials Registry (ACTRN12606000185561).
实用权重改良 Rankin 量表（UW-mRS）是一种最近提出的结局测量方法，旨在提高 mRS 的统计效率和可解释性。UW-mRS 的统计学特性已经得到了很好的研究，但结构效度尚未得到证实。
通过评估脑卒中后不同时间点和不同推导方法下 mRS 各等级内和等级间的效用值变化，探讨 UW-mRS 作为主要结局测量指标的结构效度。
从一项大型随机对照试验（AVERT）中获取了 3 个月和 12 个月（ = 2030）的生活质量评估（AQoL-4D）和 mRS 评分，利用这些数据推导 UW-mRS。通过 AQoL-4D 的受试者工作特征（ROC）分析来区分连续的 mRS 等级。采用组内相关系数来探讨脑卒中后不同时间点、UW-mRS 值和多个研究推导方法下效用值的变异性。
3 个月时 mRS 0-6 各等级的 UW-mRS 值分别为 0.80、0.78、0.63、0.37、0.11、0.03 和 0。基于 AQoL-4D 的效用值，ROC 曲线下面积从 0.54 到 0.87 不等。脑卒中后 3 个月至 12 个月间 mRS 无变化的患者，AQoL-4D 效用值的变异性有 42%-56%可以用时间来解释。推导方法的选择对 UW-mRS 值的变异性有 25%的贡献。
mRS 各等级内和等级间的效用值在脑卒中后不同时间点和使用不同推导方法时存在较大的变异性，而 UW-mRS 并不能充分反映这些变化。这些对结构效度的威胁提示在将 UW-mRS 作为主要结局测量指标时应谨慎使用。
澳大利亚新西兰临床试验注册中心（ACTRN12606000185561）。
