Department of Research Methodology, Measurement and Data Analysis, Faculty of Behavioral Sciences, University of Twente, Drienerlolaan 5, Enschede, The Netherlands.
Stat Med. 2013 Jul 30;32(17):2988-3005. doi: 10.1002/sim.5692. Epub 2012 Dec 5.
Longitudinal surveys measuring physical or mental health status are a common method to evaluate treatments. Multiple items are administered repeatedly to assess changes in the underlying health status of the patient. Traditional models to analyze the resulting data assume that the characteristics of at least some items are identical over measurement occasions. When this assumption is not met, this can result in ambiguous latent health status estimates. Changes in item characteristics over occasions are allowed in the proposed measurement model, which includes truncated and correlated random effects and a growth model for item parameters. In a joint estimation procedure adopting MCMC methods, both item and latent health status parameters are modeled as longitudinal random effects. Simulation study results show accurate parameter recovery. Data from a randomized clinical trial concerning the treatment of depression by increasing psychological acceptance showed significant item parameter shifts. For some items, the probability of responding in the middle category versus the highest or lowest category increased significantly over time. The resulting latent depression scores decreased more over time for the experimental group than for the control group and the amount of decrease was related to the increase in acceptance level.
纵向调查测量身体或心理健康状况是评估治疗效果的常用方法。通过反复进行多项测试来评估患者潜在健康状况的变化。传统的分析此类数据的模型假设至少一些项目的特征在测量期间是相同的。当这个假设不成立时，可能会导致潜在健康状况估计不明确。在提出的测量模型中允许项目特征随时间变化，该模型包括截断相关随机效应以及项目参数的增长模型。在采用 MCMC 方法的联合估计过程中，将项目和潜在健康状况参数都建模为纵向随机效应。模拟研究结果表明参数估计准确。一项关于通过增加心理接受度治疗抑郁症的随机临床试验的数据显示，项目参数有显著变化。对于某些项目，与最高或最低类别相比，中间类别的响应概率随时间显著增加。与对照组相比，实验组的潜在抑郁评分随时间的推移下降得更多，下降幅度与接受水平的提高有关。
