Tutorial: The Practical Application of Longitudinal Structural Equation Mediation Models in Clinical Trials
Tutorial: The Practical Application of Longitudinal Structural Equation Mediation Models in Clinical Trials
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DOI：
10.1037/met0000154
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发表时间：
2018-06-01
影响因子：
7
通讯作者：
Pickles, Andrew
中科院分区：
文献类型：
--
作者：
Goldsmith, Kimberley A.;MacKinnon, David P.;Pickles, Andrew
研究治疗效果的中介或治疗如何起作用，对于理解和改进心理和行为治疗很重要，但应用往往侧重于在单个时间点衡量的中介和结果。这种横断面分析不尊重调解所暗示的时间顺序。治疗的临床试验经常提供对结果的重复测量，而且越来越多地提供对介体的测量。重复测量允许应用各种类型的纵向结构方程中介模型。这为建模提供了灵活性，包括能够合并某些类型的测量误差和未测量的混杂，从而增强研究结果的稳健性。通常的方法是找出理论上最可信的模型，并应用该模型。在缺乏明确理论的情况下，我们提出了对几个理论上可信的模型进行拟合的方案，为中介假设提供了一种敏感性分析。在本教程中，我们概述了如何拟合几个纵向中介模型，包括单纯模型、潜在增长模型和潜在变化模型。这将允许读者了解感兴趣的一种类型的模型，或几种替代模型，以便他们可以采用这种敏感的方法。我们以《调步、分级活动和认知行为治疗：慢性疲劳综合征康复治疗的随机评估(PACE)试验》(ISRCTN 54285094)为激励案例，描述了如何使用与PACE试验中类似的模拟数据来拟合和解释各种纵向调节模型。给出了模拟数据集和Mplus代码及输出。
The study of mediation of treatment effects, or how treatments work, is important to understanding and improving psychological and behavioral treatments, but applications often focus on mediators and outcomes measured at a single time point. Such cross-sectional analyses do not respect the implied temporal ordering that mediation suggests. Clinical trials of treatments often provide repeated measures of outcomes and, increasingly, of mediators as well. Repeated measurements allow the application of various types of longitudinal structural equation mediation models. These provide flexibility in modeling, including the ability to incorporate some types of measurement error and unmeasured confounding that can strengthen the robustness of findings. The usual approach is to identify the most theoretically plausible model and apply that model. In the absence of clear theory, we put forward the option of fitting a few theoretically plausible models, providing a type of sensitivity analysis for the mediation hypothesis. In this tutorial, we outline how to fit several longitudinal mediation models, including simplex, latent growth and latent change models. This will allow readers to learn about one type of model that is of interest, or about several alternative models, so that they can take this sensitivity approach. We use the Pacing, Graded Activity, and Cognitive Behavioral Therapy: A Randomized Evaluation (PACE) trial of rehabilitative treatments for chronic fatigue syndrome (ISRCTN 54285094) as a motivating example and describe how to fit and interpret various longitudinal mediation models using simulated data similar to those in the PACE trial. The simulated data set and Mplus code and output are provided.