Accelerometer data reduction in adolescents: effects on sample retention and bias
Accelerometer data reduction in adolescents: effects on sample retention and bias
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DOI：
10.1186/1479-5868-10-140
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发表时间：
2013-12-23
影响因子：
8.7
通讯作者：
Troelsen, Jens
中科院分区：
文献类型：
--
作者：
Toftager, Mette;Kristensen, Peter Lund;Troelsen, Jens
背景资料：加速度计越来越被认为是评估儿童和青少年自由生活体力活动（PA）的准确可靠的方法。然而，加速度计数据减少标准仍然不一致，并且没有很好地描述排除干预研究等参与者的后果。在这项研究中，我们调查了不同的数据减少标准如何改变了青少年人口的组成保留在加速度计data analysis.Methods：加速度计数据（Actigraph GT 3X），人体测量和调查数据，从1348名青少年年龄在11-14岁的丹麦空间参加体力活动study。使用三个关键数据简化标准中的每一个的不同设置来分析加速度计数据：（1）有效天数;（2）每日佩戴时间;和（3）非佩戴时间。研究并比较了所选设置对样品保留和PA计数的影响。有序逻辑回归和多层次混合效应线性回归模型被用来分析不同的非磨损时间定义的影响，在不同的亚组定义的身体质量指数，年龄，性别，和自我报告的PA和久坐level.Results：增加最低要求的每日佩戴时间和有效天数，并应用较短的非磨损定义，导致保留在数据集中的青少年较少。此外，非佩戴时间的不同设置显著影响了哪些参与者将被保留在加速度计数据分析中。与较长的非配戴时间相比，BMI较高的青少年（OR：0.93，CI：0.87-0.98，p=0.015）和年龄较大的青少年（OR：0.68，CI：0.49-0.95，p=0.025）更有可能从使用10分钟非配戴的分析中排除。如果非佩戴时间设置较短，超重和年龄较大的青少年每天累积的非佩戴时间更多，组间的相对差异根据非佩戴设置而变化。超重和年龄较大的青少年也积累了更多的久坐不动的时间，但这是不显着相关的非磨损设置used.Conclusions：即使是在加速度计数据减少标准的微小差异可以有很大的影响样本量和PA和久坐不动的结果。本研究强调了在使用短非配戴时间定义时，将更多超重和年龄较大的青少年从分析中排除的引入偏倚的风险。
Background: Accelerometry is increasingly being recognized as an accurate and reliable method to assess free-living physical activity (PA) in children and adolescents. However, accelerometer data reduction criteria remain inconsistent, and the consequences of excluding participants in for example intervention studies are not well described. In this study, we investigated how different data reduction criteria changed the composition of the adolescent population retained in accelerometer data analysis.Methods: Accelerometer data (Actigraph GT3X), anthropometric measures and survey data were obtained from 1348 adolescents aged 11-14 years enrolled in the Danish SPACE for physical activity study. Accelerometer data were analysed using different settings for each of the three key data reduction criteria: (1) number of valid days; (2) daily wear time; and (3) non-wear time. The effects of the selected setting on sample retention and PA counts were investigated and compared. Ordinal logistic regression and multilevel mixed-effect linear regression models were used to analyse the impact of differing non-wear time definitions in different subgroups defined by body mass index, age, sex, and self-reported PA and sedentary levels.Results: Increasing the minimum requirements for daily wear time and the number of valid days and applying shorter non-wear definitions, resulted in fewer adolescents retained in the dataset. Moreover, the different settings for non-wear time significantly influenced which participants would be retained in the accelerometer data analyses. Adolescents with a higher BMI (OR: 0.93, CI: 0.87-0.98, p=0.015) and older adolescents (OR: 0.68, CI: 0.49-0.95, p=0.025) were more likely to be excluded from analysis using 10 minutes of non-wear compared to longer non-wear time periods. Overweight and older adolescents accumulated more daily non-wear time if the non-wear time setting was short, and the relative difference between groups changed depending on the non-wear setting. Overweight and older adolescents did also accumulate more sedentary time, but this was not significant correlated to the non-wear setting used.Conclusions: Even small differences in accelerometer data reduction criteria can have substantial impact on sample size and PA and sedentary outcomes. This study highlighted the risk of introducing bias with more overweight and older adolescents excluded from the analysis when using short non-wear time definitions.