Alnahdi Ali H
a Department of Rehabilitation Sciences , College of Applied Medical Sciences, King Saud University , Riyadh , Saudi Arabia.
Disabil Rehabil. 2018 Feb;40(3):353-359. doi: 10.1080/09638288.2016.1254285. Epub 2016 Nov 20.
The purpose of this study was to examine the internal construct validity of the Arabic version of the Lower Extremity Functional Scale (20-item Arabic LEFS) using Rasch analysis.
Patients (n = 170) with lower extremity musculoskeletal dysfunction were recruited. Rasch analysis of 20-item Arabic LEFS was performed. Once the initial Rasch analysis indicated that the 20-item Arabic LEFS did not fit the Rasch model, follow-up analyses were conducted to improve the fit of the scale to the Rasch measurement model. These modifications included removing misfitting individuals, changing item scoring structure, removing misfitting items, addressing bias caused by response dependency between items and differential item functioning (DIF).
Initial analysis indicated deviation of the 20-item Arabic LEFS from the Rasch model. Disordered thresholds in eight items and response dependency between six items were detected with the scale as a whole did not meet the requirement of unidimensionality. Refinements led to a 15-item Arabic LEFS that demonstrated excellent internal consistency (person separation index [PSI] = 0.92) and satisfied all the requirement of the Rasch model.
Rasch analysis did not support the 20-item Arabic LEFS as a unidimensional measure of lower extremity function. The refined 15-item Arabic LEFS met all the requirement of the Rasch model and hence is a valid objective measure of lower extremity function. The Rasch-validated 15-item Arabic LEFS needs to be further tested in an independent sample to confirm its fit to the Rasch measurement model. Implications for Rehabilitation The validity of the 20-item Arabic Lower Extremity Functional Scale to measure lower extremity function is not supported. The 15-item Arabic version of the LEFS is a valid measure of lower extremity function and can be used to quantify lower extremity function in patients with lower extremity musculoskeletal disorders.
本研究旨在使用拉施分析检验下肢功能量表阿拉伯语版（20项阿拉伯语下肢功能量表，20-item Arabic LEFS）的内部结构效度。
招募了170名下肢肌肉骨骼功能障碍患者。对20项阿拉伯语下肢功能量表进行拉施分析。一旦初始拉施分析表明20项阿拉伯语下肢功能量表不适合拉施模型，便进行后续分析以提高该量表与拉施测量模型的拟合度。这些修改包括剔除不拟合的个体、改变项目计分结构、剔除不拟合的项目、解决项目间反应依赖和差异项目功能（DIF）导致的偏差。
初始分析表明20项阿拉伯语下肢功能量表偏离拉施模型。检测到8个项目的阈值无序，6个项目间存在反应依赖，且整个量表不满足单维度要求。经过改进得到了一个15项阿拉伯语下肢功能量表，该量表具有出色的内部一致性（个人分离指数[PSI]=0.92），并满足拉施模型的所有要求。
拉施分析不支持将20项阿拉伯语下肢功能量表作为下肢功能的单维度测量工具。经过改进的15项阿拉伯语下肢功能量表满足拉施模型的所有要求，因此是下肢功能的有效客观测量工具。经过拉施验证的15项阿拉伯语下肢功能量表需要在独立样本中进一步测试，以确认其与拉施测量模型的拟合度。康复意义 20项阿拉伯语下肢功能量表测量下肢功能的效度未得到支持。15项阿拉伯语版下肢功能量表是下肢功能的有效测量工具，可用于量化下肢肌肉骨骼疾病患者的下肢功能。
