Concurrent Validity of a Self-Reported Physical Activity “Vital Sign” Questionnaire With Adult Primary Care Patients
ORIGINAL RESEARCH — Volume 13 — February 4, 2016
The number of patients eligible to participate in this study was 1,794. The number of patients who consented to participate was 305. Of the 305 participants who consented, demographic characteristics were not recorded for 7 participants. Of the 305 participants who consented, 284 reported to the MAQ that their physical activity was their “usual” weekly level. Of these 284 participants, 15 did not complete the PAVS when checking in for their appointment. The number of eligible participants, including outliers, who were ultimately included in analyses that compared physical activity reported to the PAVS with physical activity reported to the MAQ, was 269. The number of participants considered outliers by physical activity differences between the PAVS and the MAQ was 5. The number of participants considered outliers by high levels of physical activity was 3. The number of participants not considered outliers and included in final analyses was 261.
Figure 1. Recruitment and related procedures for selecting participants included for analyses in comparison of the Physical Activity “Vital Sign” questionnaire (PAVS) with the Modifiable Activity Questionnaire (MAQ), Utah, 2104. Abbreviation: PA, physical activity.
For all participants, average 95% confidence limits were wide (371.3–198.7 minutes/week). Participants reported an average of 86.3 fewer weekly minutes of activity to PAVS (128.5) compared with what they reported to MAQ (214.8; P < .001). When confidence limits were assessed by trend, the PAVS agreed more closely with the MAQ in weekly physical activity in patients who were less active. However, this agreement and upward slope of disagreement in patients with higher levels of physical activity may be because fewer patients reported higher levels of physical activity, thus causing increasingly wider limits of agreement.
Figure 2. Bland–Altman agreement of usual weekly minutes of moderate-to-vigorous physical activity assessed by the Physical Activity “Vital Sign” questionnaire (PAVS) concurrently with the Modifiable Activity Questionnaire (MAQ). A) Bland–Altman plots with 95% limits of agreement not adjusted for trend. B) Bland–Altman plots with 95% limits of agreement adjusted for trend. Larger plots signify multiple observations with identical coordinates. Abbreviations: MVA, moderate-to-vigorous physical activity; SD, standard deviation.
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