Crane Paul K, Hart Dennis L, Gibbons Laura E, Cook Karon F
Division of General Internal Medicine, University of Washington School of Medicine, Seattle, WA, USA.
J Clin Epidemiol. 2006 May;59(5):478-84. doi: 10.1016/j.jclinepi.2005.10.007. Epub 2006 Mar 14.
Measures of shoulder function may differ by dominance of affected shoulder, surgical history, gender, or race. We present a technique for determining whether observed differences in function between groups are due to biased test items or real differences in function.
Four hundred patients who were receiving rehabilitation for a variety of shoulder impairments completed a survey of shoulder function. Thirty-seven items measuring shoulder function were analyzed for differential item functioning (DIF) related to demographic characteristics using an ordinal logistic regression (OLR) and item response theory (IRT) approach. When DIF was identified in an item, we modified the IRT analysis to calibrate item parameters separately in appropriate demographic groups. We compared adjusted and unadjusted patient ability measures in each demographic group.
Several items were found to have a modest amount of DIF related to the different demographic characteristics, especially gender; however, adjusting measures for DIF had little impact on overall measures of shoulder function and made almost no difference in average shoulder function across demographic groups.
In this pool of shoulder function items, adjustment for DIF made almost no difference in measures of function across demographic groups.
肩部功能的测量结果可能因患侧肩部的优势、手术史、性别或种族而有所不同。我们提出一种技术，用于确定组间观察到的功能差异是由于测试项目存在偏差还是功能的实际差异。
四百名因各种肩部损伤接受康复治疗的患者完成了一项肩部功能调查。使用有序逻辑回归（OLR）和项目反应理论（IRT）方法，对37项测量肩部功能的项目进行了与人口统计学特征相关的差异项目功能（DIF）分析。当在某个项目中识别出DIF时，我们修改IRT分析，以便在适当的人口统计学组中分别校准项目参数。我们比较了每个人口统计学组中调整前后的患者能力测量结果。
发现有几个项目存在与不同人口统计学特征相关的适度DIF，尤其是性别；然而，对DIF进行调整对肩部功能的总体测量几乎没有影响，并且在不同人口统计学组的平均肩部功能方面几乎没有差异。
在这个肩部功能项目库中，对DIF进行调整在不同人口统计学组的功能测量方面几乎没有差异。
