Department of Epidemiology and Biostatistics, The EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands.
J Clin Epidemiol. 2013 Jul;66(7):775-82; quiz 782.e1-2. doi: 10.1016/j.jclinepi.2013.02.005. Epub 2013 Apr 22.
To determine the content, structural, and construct validity of the Dutch version of the Neck Disability Index (NDI).
To assess content validity, 11 neck pain experts and 10 patients commented on the construct, comprehensiveness, and relevance of the NDI. Structural validity was assessed by item factor analysis (FA) and item response theory modeling using the generalized partial credit model. Differential item functioning (DIF) analysis for gender was examined. Pearson correlation coefficient with the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire was calculated to assess construct validity.
In addition to a suboptimal translation, we found a lack of consensus on the construct the NDI intends to measure. Experts and patients suggested that the NDI measures more than physical functioning. Unidimensionality of the NDI could not be confirmed. DIF analysis for gender showed DIF for the headache item. The goodness-of-fit statistics for FA with one factor were satisfactory when the item "concentration" was omitted. A correlation of 0.75 with the DASH was found supporting construct validity.
It is questionable whether in research the NDI should be the instrument of choice for use as a primary outcome measure. Definition of the construct to be measured is a prerequisite for the assessment of validity.
确定荷兰语版颈部残疾指数（NDI）的内容、结构和构念效度。
为评估内容效度，11 名颈部疼痛专家和 10 名患者对 NDI 的构念、全面性和相关性进行了评论。结构效度通过项目因子分析（FA）和广义部分信用模型的项目反应理论建模进行评估。对性别进行了差异项目功能（DIF）分析。与手臂、肩部和手部残疾问卷（DASH）的 Pearson 相关系数用于评估构念效度。
除了翻译不够理想之外，我们还发现专家和患者对 NDI 旨在测量的构念缺乏共识。专家和患者认为 NDI 不仅测量身体功能。NDI 的单维性无法得到证实。性别差异分析显示，头痛项目存在 DIF。当省略“注意力集中”这一项时，FA 的拟合优度统计量为一个因子时令人满意。与 DASH 的相关性为 0.75，支持构念效度。
在研究中，NDI 是否应作为首选的主要结果测量工具存在疑问。测量的构念定义是评估效度的前提。
