Fleishman John A, Lawrence William F
Center for Cost and Financing Studies, Agency for Healthcare Research and Quality, Rockville, Maryland 20852, USA.
Med Care. 2003 Jul;41(7 Suppl):III75-III86. doi: 10.1097/01.MLR.0000076052.42628.CF.
Demographic differences have been reported in summary measures of physical and mental health based on the SF-12 instrument.
This study examines the extent to which differential item functioning (DIF) contributes to observed subgroup differences in health status. DIF refers to situations in which the psychometric properties of items are not invariant across different groups. The presence of DIF confounds interpretation of subgroup differences.
A national sample of 11,626 adult respondents in the 2000 Medical Expenditure Panel Survey who completed a self-administered questionnaire.
In addition to the SF-12, we collected data on demographic characteristics (age, gender, education, and race/ethnicity) and whether the person had ever been diagnosed with six chronic medical conditions.
Multiple-indicator multiple-cause latent variable models showed significant differences in physical health by gender, age, and education. Adjusting for DIF reduced but did not eliminate age and education differences. However, for mental health, adjusting for DIF resulted in Black-White differences becoming nonsignificant, and the effect for the oldest age group switched from positive to negative. Race/ethnicity was not associated with physical health status.
Age group comparisons of mental health may be particularly affected by DIF. Differences in education, as well as age and gender, need to be controlled when making group comparisons. Additional work is needed to understand factors that give rise to demographic differences in reported health status.
基于SF - 12量表的身心健康综合测量结果显示存在人口统计学差异。
本研究考察了项目功能差异（DIF）在多大程度上导致了健康状况观察到的亚组差异。DIF指的是项目的心理测量特性在不同群体中并非不变的情况。DIF的存在会混淆亚组差异的解释。
2000年医疗支出小组调查中全国范围内11626名成年受访者的样本，他们完成了一份自填式问卷。
除了SF - 12量表外，我们收集了人口统计学特征（年龄、性别、教育程度和种族/族裔）以及该人是否曾被诊断患有六种慢性疾病的数据。
多指标多原因潜在变量模型显示，在身体健康方面，性别、年龄和教育程度存在显著差异。调整DIF后，年龄和教育程度差异有所减少，但并未消除。然而，对于心理健康，调整DIF后，黑人和白人之间的差异变得不显著，最年长者群体的影响从正向变为负向。种族/族裔与身体健康状况无关。
心理健康的年龄组比较可能特别受DIF影响。在进行组间比较时，需要控制教育程度以及年龄和性别的差异。需要开展更多工作来了解导致报告健康状况存在人口统计学差异的因素。
