Patterns of intra-cluster correlation from primary care research to inform study design and analysis
Patterns of intra-cluster correlation from primary care research to inform study design and analysis
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DOI：
10.1016/j.jclinepi.2003.12.013
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发表时间：
2004-08-01
影响因子：
7.2
通讯作者：
Campbell, MJ
中科院分区：
文献类型：
--
作者：
Adams, G;Gulliford, MC;Campbell, MJ
目的：为初级保健中的整群研究提供有关组内相关系数(ICC)大小的信息。研究设计和设置：重新分析31项初级保健中的整群研究的数据，使用最大似然估计从随机效应模型中估计组内相关系数。结果：估计了1,039个变量的ICCS。中位数ICC为0.010(四分位数范围0~0.032，0~0.840)。在调整了个体和集群水平的特征后，中位数ICC为0.005(IQR0到0.021)。给定的测量结果显示，不同数据集中的ICC估计值差异很大。在6个数据集中，SF-36身体功能量表的ICC范围为0.001至0.055，SF-36一般健康的ICC为0至0.072。在四个数据集中，收缩压的IC值从0到0.052，舒张压的IC值从0到0.108。结论：给定测量的组间差异的精确程度很难事先估计。设计研究时应参考ICC的总体分布，并注意提高效率的特点。(C)2004 Elsevier Inc.保留所有权利。
Objective: To provide information concerning the magnitude of the intraclass correlation coefficient (ICC) for cluster-based studies set in primary care.Study Design and Setting: Reanalysis of data from 31 cluster-based studies in primary care to estimate intraclass correlation coefficients from random effects models using maximum likelihood estimation.Results: ICCs were estimated for 1,039 variables. The median ICC was 0.010 (interquartile range [IQR] 0 to 0.032, range 0 to 0.840). After adjusting for individual- and cluster-level characteristics, the median ICC was 0.005 (IQR 0 to 0.021). A given measure showed widely varying ICC estimates in different datasets. In six datasets, the ICCs for SF-36 physical functioning scale ranged from 0.001 to 0.055 and for SF-36 general health from 0 to 0.072. In four datasets, the ICC for systolic blood pressure ranged from 0 to 0.052 and for diastolic blood pressure from 0 to 0.108.Conclusion: The precise magnitude of between-cluster variation for a given measure can rarely be estimated in advance. Studies should be designed with reference to the overall distribution of ICCs and with attention to features that increase efficiency. (C) 2004 Elsevier Inc. All rights reserved.