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The improved physical activity index for measuring physical activity in EPIC Germany
Angelika Wientzek1, Matthäus Vigl1, Karen Steindorf2
1Department of Epidemiology, German Institute of Human Nutrition Potsdam-Rehbruecke, Nuthetal, Germany.
Plos One
|March 20, 2014
Summary
A new Improved Physical Activity Index (IPAI) was developed for the EPIC study. This index accurately measures physical activity (PA) continuously and categorizes individuals, outperforming previous methods in populations with increasing non-working participants.
Area of Science:
- Epidemiology
- Public Health
- Biostatistics
Background:
- Traditional physical activity (PA) indexing in the European Investigation into Cancer and Nutrition (EPIC) study relied on work and recreational activity cross-tabulation.
- The increasing proportion of non-working participants necessitates alternative PA assessment strategies.
- Existing indices may not adequately capture PA in diverse populations, particularly those with fewer working individuals.
Purpose of the Study:
- To develop and validate a novel physical activity index (IPAI) suitable for the EPIC study population.
- To create an index capable of expressing physical activity on a continuous scale.
- To improve PA assessment in populations with a growing number of non-working individuals.
Main Methods:
- A clustered sample of 3,766 participants from German EPIC centers was invited, with 1,344 ultimately included.
- Physical activity was measured using questionnaires and a 7-day combined heart rate and acceleration sensor.
- The Improved Physical Activity Index (IPAI) was developed in a training sample (n=433) and validated against accelerometer data and physical activity energy expenditure (PAEE) in a separate sample (n=911).
Main Results:
- The IPAI demonstrated higher correlations with accelerometer counts (r=0.40-0.43) and PAEE (r=0.33-0.40) compared to the Cambridge Index and Total PA Index in both training and validation samples.
- In non-working participants, the IPAI showed superior performance with correlations of r=0.34 for accelerometer counts and r=0.29 for PAEE.
- The IPAI effectively categorizes participants by PA level and provides continuous PA measurement.
Conclusions:
- The Improved Physical Activity Index (IPAI) is a valid and effective tool for assessing physical activity.
- The IPAI offers improved performance over established indices, especially in populations with a higher prevalence of non-working individuals.
- This new index enhances the ability to continuously measure and categorize physical activity within large epidemiological studies like EPIC.
