VALIDATION OF AN OCCUPATIONAL PHYSICAL ACTIVITY QUESTION IN BRFSS

Abstract

PURPOSE To test the validity of a new question designed to measure occupational physical activity (PA) for the 2001 Behavioral Risk Factor Surveillance System (BRFSS). METHODS The question measured 3 intensity levels of occupational-related activity: mostly sitting or standing, mostly walking, and mostly heavy labor or physically demanding work. Two validation studies of this question were conducted during 1998–2000. Study 1 had 92 participants (49% male, 77% white) who, for three weeks, completed a daily activity log indicating time spent in work-related PA and responded to the occupational activity question. Study 2 had 60 participants (50% male, 85% white), who completed a one-week daily activity log and responded to the same occupational activity question. Occupational activity log data (the validation criterion) were grouped into the three response categories and compared using the kappa statistic. RESULTS In Study 1, kappa ranged from 0.20 to 0.41. Although 12 people had a BRFSS self-classification of “mostly walking”, only two (17%) spent the majority of their time at work walking. In Study 2, kappa=0.37; four people had a self-classification of “mostly walking”, but only one spent the majority of their time walking. Validation was not possible for the “heavy labor” category (n=2). However, those classified as “mostly walking” did more occupational walking (Study 1:630 ± 513 minutes/week; Study 2:496 ± 499 minutes/week) than the “mostly sitting” group (Study 1:268 ± 408 minutes/week; Study 2:243 ± 210 minutes/week). CONCLUSION The validity of the BRFSS occupational activity question is fair and comparable to other questionnaires. Respondents classified as “mostly walking” did not walk the majority of their time at work, but did walk more than the “mostly sitting or standing” group. Research among more diverse populations, including people of different racial/ethnic groups and persons in heavy labor occupations, is needed to further understand the validity of the occupational PA questions.