Convergent validity of a brief self-reported physical activity questionnaire.
OBJECTIVE
The objective of this study is to determine whether summary estimates of a self-report physical activity questionnaire that does not specifically assess frequency or duration (the Coronary Artery Risk Development in Young Adults (CARDIA) physical activity history (PAH)) differs from the summary estimates of one that does (CARDIA Supplemental Questionnaire).


METHODS
After the year 25 examination (2010-2011), 203 CARDIA black and white men and women (age 50.3 ± 3.6 yr) at the Oakland, CA, site participated in this comparison study. The between-questionnaire association and agreement were determined for continuous and categorical estimates on the basis of 1) quartiles and 2) meeting 2008 physical activity guidelines. Differences in participant characteristics by concordance/discordance status were also examined. Finally, receiver operating characteristic curves were computed to determine the accuracy of the PAH compared with the supplemental questionnaire.


RESULTS
Reported physical activity levels were high and varied significantly by race and sex (all P < 0.01). Between-questionnaire estimates were significantly correlated (rho = 0.75 to 0.90, all P < 0.001) and had high agreement (κ = 0.51 to 0.80) across all race/sex groups. A higher proportion of women than men were classified as concordant by quartile of vigorous intensity (P = 0.001), but no other participant characteristics were associated with concordant/discordant quartile ranking. Participants classified as concordant on the basis of physical activity guidelines had lower body mass index than those classified as discordant (both P < 0.05). The area under the curve was 0.95, suggesting that the PAH has high accuracy for classifying individuals as meeting physical activity guidelines.


CONCLUSIONS
Although it is inconvenient that the PAH is not expressed in more standard units, these findings support the practice of not directly assessing frequency and duration, which are frequent sources of reporting error.
1Division of Epidemiology, Human Genetics and Environmental Sciences, University of Texas Health Science Center at Houston, Austin, TX; 2Division of Research, Kaiser Permanente Northern California, Oakland, CA; 3Division of Epidemiology and Community Health, University of Minnesota, Minneapolis, MN; and 4Division of Cardiovascular Sciences, Program in Prevention and Population Sciences, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD.
Kelley Pettee
KP
Gabriel
Stephen
S
Sidney
David R
DR
Jacobs
Charles P
CP
Quesenberry
Jared P
JP
Reis
Sheng-Fang
SF
Jiang
Barbara
B
Sternfeld
D015992:Body Mass Index; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D044469:Racial Groups; D015203:Reproducibility of Results; D057566:Self Report; D012737:Sex Factors; D011795:Surveys and Questionnaires