Intraclass correlation coefficients for school-based HIV/STI prevention trials

描述（由申请人提供）：这个R03研究项目的特点是对来自四个联邦资助的基于学校的艾滋病毒/性传播感染预防干预的纵向组随机试验（GRTs）的数据集进行二次分析，为该领域提供所需的类内相关系数（ICCs）估计-这是确定在规划GRTs时以足够的力量和精度估计干预效果所需的样本量的关键参数。研究表明，ICC估计值因结果、人群、环境和研究设计而有很大差异，ICC估计值的微小变化会对研究的能力和精度产生很大影响（Murray, 1998; Donner and Klar, 2000; Rotondi and Donner, 2009; Resnicow et al., 2010）。因此，在过去的十年中，研究人员被敦促公布对更广泛的结果、人群和环境的估计，以便更有效地规划未来的试验（Murray等人，2004；Resnicow等人，2010；Murray和Blitstein, 2003； Pals等人，2009）。该项目将采用2级（学生嵌套在学校）和3级（学生嵌套在教室嵌套在学校）多层模型来分析每个数据集的横截面，为该领域提供第一套学校级ICC估计，具体用于规划以性冒险结果为重点的以学校为基础的艾滋病毒预防干预措施的横截面和测试前/测试后GRTs。此外，方法学和软件的最新进展提供了在规划纵向grt时，通过使用来自3级重复测量模型的ICC或方差成分参数的估计来改进样本量确定的潜力。然而，在任何健康风险预防领域，对这些参数的估计很少发表（Murray和Blitstein, 2003； Murray等人，2006；Murray等人，2007；Moonseong和Leon, 2008； Spybrook等人，2009）。本研究将使用重复测量多级模型来获得这些参数的初步估计，以规划以学校为基础的艾滋病毒预防干预的纵向grt。在所有情况下，将分析有协变量调整和没有协变量调整的模型，以提供信息，说明调整协变量可能在多大程度上减少icc，以及以学校为基础的艾滋病毒/性传播感染预防干预的grt所需的样本量。还将检查各种ICC和方差分量估计对检测常见效应量所需的样本量的影响。这项研究的结果将通过同行评议的文章和会议报告提供，以便使计划未来以学校为基础的艾滋病毒/性传播感染预防研究的科学家受益。鉴于学校作为向青少年提供预防干预措施的场所的重要性以及与实施基于学校的grt相关的成本，有效规划这些试验至关重要。

DESCRIPTION (provided by applicant): This R03 research project features secondary analyses of datasets from four federally-funded longitudinal group randomized trials (GRTs) of school-based HIV/STI prevention interventions to provide the field with needed estimates of intraclass correlation coefficients (ICCs) - a parameter critical for determining the sample size necessary for estimating intervention effects with adequate power and precision when planning GRTs. Studies have shown that ICC estimates vary widely depending on the outcome, population, setting, and study design, and small changes in ICC estimates can have large effects on study power and precision (Murray, 1998; Donner and Klar, 2000; Rotondi and Donner, 2009; Resnicow et al., 2010). Consequently, in the past decade researchers have been urged to publish estimates for a wider variety of outcomes, populations and settings so that future trials can be planned more efficiently (Murray et al., 2004; Resnicow et al., 2010; Murray and Blitstein, 2003; Pals et al., 2009). This project would employ 2-level (students nested within schools) and 3-level (students nested within classrooms nested within schools) multilevel models to analyze cross sections of each dataset to provide the field with the first set of school-level ICC estimates specific to planning cross- sectional and pretest/posttest GRTs of school-based HIV prevention interventions focused on sexual risk- taking outcomes. In addition, recent advances in methodology and software provide the potential to refine sample size determinations when planning longitudinal GRTs by using estimates of ICC or variance component parameters from 3-level repeated measures models. Yet very few estimates of these parameters have been published in any health risk prevention field (Murray and Blitstein, 2003; Murray et al., 2006; Murray et al., 2007; Moonseong and Leon, 2008; Spybrook et al., 2009). This study would use repeated measures multilevel models to obtain the first estimates of these parameters for planning longitudinal GRTs of school- based HIV prevention interventions. In all cases, models with and without adjustment for covariates would be analyzed to contribute information on the extent to which adjustment for covariates may reduce ICCs and needed sample size in school-based GRTs of HIV/STI prevention interventions. The effects of the various ICC and variance component estimates on the sample size needed to detect commonly seen effect sizes also would be examined. The results of this study would be made available through peer-reviewed articles and conference presentations in order to benefit researchers planning future school-based HIV/STI prevention studies. Efficient planning of these trials is critical given the importance of schools as a venue for delivering prevention interventions to adolescents and the costs associated with implementing school-based GRTs. PUBLIC HEALTH RELEVANCE: Schools are an important venue for HIV/STI prevention interventions because most youth attend schools, making them efficient sites for program delivery. Rigorous evaluation of these interventions is critical to ensure public health resources are applied to programs that have meaningful effects on the rates of HIV and other STIs in youth. The gold standard for rigorous evaluation of school-based HIV prevention interventions is the group randomized trial (GRT), but planning such trials with the sample size (number of schools/students) necessary for estimating intervention effects with adequate power and precision requires estimates of the intraclass correlation coefficient (ICC) parameter from studies involving similar outcomes, populations and settings. This project would provide the first ICC parameter estimates specific to HIV/STI-related behavioral and psychosocial outcomes across a variety of different school settings and populations so that researchers in the field could select the most appropriate ICCs for efficiently sizing these costly studies.