Validity of a short questionnaire to assess physical activity in 10 European countries
The InterAct Consortium
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The InterAct Consortium (&) Cambridge
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UK
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InterAct project was coordinated by the Medical Research Council Epidemiology Unit
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Cambridge
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UK
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The members of the InterAct consortium is given in Appendix
To accurately examine associations of physical activity (PA) with disease outcomes, a valid method of assessing free-living activity is required. We examined the validity of a brief PA questionnaire (PAQ) used in the European Prospective Investigation into Cancer and Nutrition (EPIC). PA energy expenditure (PAEE) and time spent in moderate and vigorous physical activity (MVPA) was measured in 1,941 healthy individuals from 10 European countries using individually-calibrated combined heart-rate and movement sensing. Participants also completed the short EPIC-PAQ, which refers to past year's activity. Pearson (r) and Spearman (r) correlation coefficients were calculated for each country, and random effects meta-analysis was used to calculate the combined correlation across countries to estimate the validity of two previously- and one newly-derived ordered, categorical PA indices (''Cambridge index'', ''total PA index'', and ''recreational index'') that categorized individuals as inactive, moderately inactive, moderately active, or active. The strongest associations with PAEE and MVPA were observed for the Cambridge index (r = 0.33 and r = 0.25, respectively). No significant heterogeneity by country was observed for this index (I2 = 36.3%, P = 0.12; I2 = 0.0%, P = 0.85), whereas heterogeneity was suggested for other indices (I2 [ 48%, P \ 0.05, I2 [ 47%, P \ 0.05). PAEE increased linearly across self-reported PA categories (P for trend 0.001), with an average difference of approximately 460 kJ/d for men and 365 kJ/d for women, between categories of the Cambridge index. The EPIC-PAQ is suitable for categorizing European men and women into four distinct categories of overall physical activity. The difference in PAEE between categories may be useful when estimating effect sizes from observational research.
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Physical inactivity is a major risk factor for mortality and
for several chronic diseases, including type 2 diabetes [1].
Large cohort studies are required to examine the etiology
of chronic disease outcomes among healthy individuals,
and in large, multi-site prospective studies of physical
activity in relation to chronic disease, self-report methods
such as physical activity questionnaires (PAQs) are
currently the most feasible method for assessing physical
activity. PAQs are commonly used for practical reasons
such as limiting cost and reducing participant and
researcher burden, and PAQs have been used for several
purposes, including international surveillance (e.g., the
International Physical Activity Questionnaire [IPAQ] [2]),
risk stratification (e.g., the EPIC Physical Activity
Questionnaire [EPIC-PAQ] [3]), and etiologic investigation (e.g.
the short European Prospective Investigation into Cancer
and Nutrition [EPIC]-Norfolk Physical Activity
Questionnaire [EPAQ2] [4]). However, PAQs may misclassify an
individuals physical activity level due to deliberate
misreporting or cognitive limitations related to recall or
comprehension [5, 6]. Therefore, it is necessary to examine
the validity of any self-report instrument using independent
criterion methods in a population representative of that in
which it is used for answering epidemiological questions.
The EPIC study was designed to investigate the
relationship of nutrition and cancer in over 500,000 individuals
from 10 European countries [7]. At enrolment (19922000),
study participants completed questionnaires assessing diet
and lifestyle factors, including physical activity.
Specifically, physical activity was assessed by a brief questionnaire
(the short EPIC-PAQ) interrogating occupational,
household, and recreational activities during the past year [8].
An initial evaluation of the validity of questions selected
from a more extensive questionnaire used in a pilot study
of the EPIC protocol that resembled questions interrogated
by the short EPIC-PAQ was performed in the Netherlands
[9]. The authors assessed the validity and reliability of
these representative questions against physical activity
reported on 3-day diaries and determined that although the
absolute validity and reliability of the questions for
estimating physical activity energy expenditure (PAEE) was
poor, the questionnaire would be suitable for ranking
physical activity levels.
Accordingly, two indices for categorizing physical
activity levels have been derived from the short
EPICPAQ, the Cambridge index [3] and the total physical
activity index [10]. The validity of these indices for
categorizing individuals physical activity levels has not yet
been assessed in the EPIC cohort. Therefore, the aim of
this study was to evaluate the validity of these indices for
ranking physical activity among adults from the 10
countries participating in the EPIC-Eu (...truncated)