Rhew Isaac C, Hawkins J David, Murray David M, Fagan Abigail A, Oesterle Sabrina, Abbott Robert D, Catalano Richard F
Prev Sci. 2016 Feb;17(2):177-87. doi: 10.1007/s11121-015-0613-4.
The Communities That Care (CTC) prevention system has shown effects on reducing incidence and prevalence of problem behaviors among a panel of youth followed from 5th through 12th grade. The present report examines whether similar intervention effects could be observed using a repeated cross-sectional design in the same study. Data were from a community-randomized trial of 24 US towns. Cross-sectional samples of sixth, eighth, and tenth graders were surveyed at four waves. Two-stage ANCOVA analyses estimated differences between CTC and control communities in community-level prevalence of problem behaviors for each grade, adjusting for baseline prevalence. No statistically significant reductions in prevalence of problem behaviors were observed at any grade in CTC compared to control communities. Secondary analyses examined intervention effects within a “pseudo cohort” where cross-sectional data were used from sixth graders at baseline and tenth graders 4 years later. When examining effects within the pseudo cohort, CTC compared to control communities showed a significantly slower increase from sixth to tenth grade in lifetime smokeless tobacco use but not for other outcomes. Exploratory analyses showed significantly slower increases in lifetime problem behaviors within the pseudo cohort for CTC communities with high, but not low, prevention program saturation compared to control communities. Although CTC demonstrated effects in a longitudinal panel from the same community-randomized trial, we did not find similar effects on problem behaviors using a repeated cross-sectional design. These differences may be due to a reduced ability to detect effects because of potential cohort effects, accretion of those who were not exposed, and attrition of those who were exposed to CTC programming in the repeated cross-sectional sample.
“关爱社区”(CTC)预防系统已显示出对减少从五年级到十二年级的一组青少年中问题行为的发生率和流行率有效果。本报告研究了在同一研究中使用重复横断面设计是否能观察到类似的干预效果。数据来自对美国24个城镇的社区随机试验。对六年级、八年级和十年级的横断面样本进行了四轮调查。两阶段协方差分析估计了CTC社区和对照社区在每个年级问题行为的社区层面流行率之间的差异,并对基线流行率进行了调整。与对照社区相比,在CTC的任何年级都未观察到问题行为流行率有统计学上的显著降低。二次分析在一个“虚拟队列”中检验了干预效果,其中使用了基线时六年级学生和4年后十年级学生的横断面数据。在检验虚拟队列中的效果时,与对照社区相比,CTC在终生无烟烟草使用方面从六年级到十年级的增长明显较慢,但其他结果并非如此。探索性分析表明,与对照社区相比,对于预防项目饱和度高而非低的CTC社区,虚拟队列中终生问题行为的增长明显较慢。尽管CTC在同一社区随机试验的纵向队列中显示出效果,但我们使用重复横断面设计未发现对问题行为有类似效果。这些差异可能是由于潜在队列效应、未暴露者的累积以及重复横断面样本中接触CTC项目者的损耗导致检测效果的能力降低。