Crane Paul K, Gibbons Laura E, Jolley Lance, van Belle Gerald, Selleri Ricardo, Dalmonte Edoardo, De Ronchi Diana
Department of Internal Medicine, Harborview Medical Center, University of Washington, Seattle, WA 98104, USA.
Int Psychogeriatr. 2006 Sep;18(3):505-15. doi: 10.1017/S1041610205002978. Epub 2006 Feb 15.
Differential item functioning (DIF) exists when test item responses by members of different demographic groups are statistically different when controlling for ability. DIF may indicate item bias. Our objective was to determine whether items from the Italian Mini-mental State Examination (MMSE) had DIF related to educational attainment, age, gender and occupation. We were also interested in exploring the significance of DIF in screening tests.
In a two-stage study from Granarolo, Italy, residents over age 61 (n = 495) were evaluated with the Italian MMSE. Those with MMSE scores of 28 or lower were further evaluated for dementia. MMSE results were coded in 10 item bundles. We used ordinal logistic regression to determine whether item bundles had DIF.
Six of the 10 MMSE item bundles had DIF in educational attainment subgroups. Four of these six bundles also had DIF related to age. Items that required literacy were much harder for those with lower educational attainment.
DIF related to education appeared at as few as 3 years of formal schooling. These findings suggest cautious interpretation of data from studies using the Italian MMSE in populations with heterogeneous educational backgrounds. DIF is especially troublesome for two-stage studies that use screening tests.
当在控制能力的情况下，不同人口统计学群体的测试项目回答在统计学上存在差异时，就存在项目功能差异（DIF）。DIF可能表明项目存在偏差。我们的目的是确定意大利简易精神状态检查表（MMSE）中的项目是否存在与教育程度、年龄、性别和职业相关的DIF。我们还对探索DIF在筛查测试中的意义感兴趣。
在意大利格拉纳罗洛进行的一项两阶段研究中，对61岁以上的居民（n = 495）进行了意大利MMSE评估。MMSE得分28分及以下的患者进一步接受痴呆症评估。MMSE结果被编码为10个项目组。我们使用有序逻辑回归来确定项目组是否存在DIF。
10个MMSE项目组中有6个在教育程度亚组中存在DIF。这6个组中的4个也存在与年龄相关的DIF。对于教育程度较低的人来说，需要识字能力的项目要难得多。
与教育相关的DIF在仅接受3年正规学校教育的人群中就已出现。这些发现表明，对于在教育背景各异的人群中使用意大利MMSE进行的研究数据，应谨慎解读。对于使用筛查测试的两阶段研究而言，DIF尤其棘手。
