Kangwanrattanakul Krittaphas
Division of Social and Administrative Pharmacy, Faculty of Pharmaceutical Sciences, Burapha University, Chonburi, Thailand.
J Pharm Policy Pract. 2025 Sep 5;18(1):2551224. doi: 10.1080/20523211.2025.2551224. eCollection 2025.
Although the 12-item Short Form Health Survey version 2 (SF-12v2) is suitable for measuring health status in the general Thai population, it has been evaluated using classical test theory. Rasch analysis, however, offers a psychometric testing method that converts ordinal scales to interval-level data without breaching parametric assumptions. Thus, this study aimed to assess the measurement properties of Thai SF-12v2 and SF-6D items derived from it among the general Thai population.
Rasch analysis was performed on 300 participants randomly selected from a pool of 1200 general Thai population. The initial SF-12v2 items, physical component summary (PCS), mental component summary (MCS), and SF-6D items were evaluated for overall fit to the Rasch model using the Chi-square test and several key elements of Rasch measurement properties, including unidimensionality, reliability (internal consistency), local independence, ordering thresholds, targeting, and item invariance (differential item functioning [DIF]).
The two-domain subtests of the SF-12v2 showed an acceptable fit to the Rasch model (χ[12] = 20.16, = 0.06), unidimensionality, satisfactory reliability (PSI = 0.72), local independence, and no significant DIF. Although five items initially misfitted the Rasch model, these issues were resolved in the subtest analysis. Individual PCS and MCS were not recommended for measuring health status due to inadequate reliability. The SF-6D items demonstrated a good overall model fit (χ[20] = 23.18, = 0.28), unidimensionality, local independence, and good internal consistency (PSI = 0.73). However, all scales showed poor targeting for the person-item threshold distribution.
Rasch analysis supports the use of two-domain subtests of the SF-12v2 questionnaire for between-group analysis in the general Thai population. However, it does not support the use of individual PCS and MCS due to poor reliability. The SF-6D, achieving satisfactory reliability, was endorsed for eliciting utility scores for between-group analysis.
尽管12项简明健康调查问卷第2版（SF - 12v2）适用于测量泰国普通人群的健康状况，但此前一直是使用经典测试理论进行评估的。然而，拉施分析提供了一种心理测量测试方法，可将顺序量表转换为等距水平数据，且不违反参数假设。因此，本研究旨在评估泰国SF - 12v2及其衍生的SF - 6D项目在泰国普通人群中的测量属性。
对从1200名泰国普通人群中随机抽取的300名参与者进行拉施分析。使用卡方检验和拉施测量属性的几个关键要素，包括单维度性、可靠性（内部一致性）、局部独立性、排序阈值、目标定位和项目不变性（项目功能差异[DIF]），对初始的SF - 12v2项目、身体成分总结（PCS）、心理成分总结（MCS）和SF - 6D项目进行拉施模型整体拟合评估。
SF - 12v2的两个领域子测试显示出与拉施模型的可接受拟合度（χ[12] = 20.16， = 0.06）、单维度性、令人满意的可靠性（PSI = 0.72）、局部独立性，且无显著的DIF。尽管最初有5个项目与拉施模型不拟合，但这些问题在子测试分析中得到了解决。由于可靠性不足，不建议使用个体PCS和MCS来测量健康状况。SF - 6D项目显示出良好的整体模型拟合度（χ[20] = 23.18， = 0.28）、单维度性、局部独立性和良好的内部一致性（PSI = 0.73）。然而，所有量表在人员 - 项目阈值分布方面均显示出较差的目标定位。
拉施分析支持在泰国普通人群的组间分析中使用SF - 12v2问卷的两个领域子测试。然而，由于可靠性较差，不支持使用个体PCS和MCS。SF - 6D具有令人满意的可靠性，被认可用于获取组间分析的效用分数。
