Related Experiment Video
Updated: Mar 25, 2026
Visualization of Intensity Levels to Reduce the Gap Between Self-Reported and Directly Measured Physical Activity
Published on: March 7, 2019
Rates of attrition, non-compliance and missingness in randomized controlled trials of child physical activity
Erin K Howie1, Leon M Straker1
1School of Physiotherapy and Exercise Science, Curtin University, Australia.
Insights
Missing data is frequent in childhood physical activity trials using accelerometers, with high rates of participant attrition and non-compliance. Inconsistent handling of this missingness necessitates better study design and reporting strategies.
Area of Science:
- Pediatric Exercise Science
- Clinical Trial Methodology
- Biomedical Data Analysis
Background:
- Physical activity is crucial for child health.
- Accelerometers are widely used to objectively measure physical activity in research.
- Randomized controlled trials (RCTs) are key for evaluating interventions, but participant adherence can be challenging.
Purpose of the Study:
- To quantify missingness due to attrition and non-compliance in pediatric physical activity RCTs.
- To assess how missing data is handled in studies utilizing accelerometry.
- To identify factors influencing missingness in this population.
Main Methods:
- Systematic review of the literature.
- Searched MEDLINE for physical activity RCTs in children (ages 2-18) using accelerometers (1996-2015).
- Extracted attrition and non-compliance rates from 23 eligible studies.
Main Results:
- Mean attrition rate was 11.5%; mean accelerometer non-compliance was 22.7% at baseline and 29.6% at follow-up.
- Overall mean study missingness reached 37.4%, with significant variation between studies.
- No significant differences in missingness were found based on study characteristics like sample size, age, setting, or duration.
Conclusions:
- Missing data is a substantial issue in pediatric physical activity RCTs employing accelerometry.
- Current methods for addressing missingness are inconsistent across studies.
- Future research requires proactive planning for and transparent reporting of missing data in trial design and analysis.
Objectives:
The purpose of this brief review was to describe the missingness, from both attrition and non-compliance, during physical activity randomized controlled trials among children which have used accelerometers to measure physical activity.
Design:
Systematic review.
Methods:
Using a previously published search strategy, an updated search of the literature was performed in the MEDLINE database for articles published from 1996 to February 2015 identifying physical activity RCTs in children (ages 2-18) measuring physical activity using accelerometers. Rates of attrition and non-compliance were extracted from identified articles. Twenty-three independent studies provided complete attrition and non-compliance data and were included.
Results:
The mean attrition rate was 11.5% (SD 10.1%, range 0-30.9%). The mean accelerometer non-compliance rate at baseline was 22.7% (SD 16.4%, range 1.7-67.8%) and 29.6% (SD 19.4%, range 3.3-70.1%) at follow-up. The mean total study missingness was 37.4% (SD 20.2%, range 3.3-75.4%) and ranged from 3.3% to 75.4%. There was large variation in how missingness was accounted for between studies. There were no statistically significant differences in missingness between study characteristics including sample size, participant age, intervention setting, duration of follow-up, whether physical activity was the primary outcome, and weartime compliance criteria.
Conclusions:
Missingness is common among randomized controlled trials using accelerometry in children and is currently handled inconsistently. Researchers must plan for high levels of missingness in study design and account for missingness in reporting and analyses of trial outcomes.
Related Concept Videos
02:20Longitudinal Research
01:13Randomized Experiments
Simple randomization
Simple...
01:09Censoring Survival Data