Validity of two brief physical activity questionnaires with accelerometers among African-American women

Aim To evaluate the validity of the Stanford Brief Activity Survey (SBAS) and Exercise Vital Sign (EVS) questionnaire against accelerometer-determined time in moderate-to-vigorous physical activity (MVPA) among African-American (AA) women. Background Limited research has evaluated the validity of brief physical activity (PA) questionnaires among AA women. Since the validity of PA questionnaires may differ among members of varying racial/ethnic groups, research is needed to explore the validity of self-report PA measures among AA women. Methods A total of 30 AA women [M age=35.5±5.3; M body mass index (BMI)=31.1±7.8] wore ActiGraph GT3X+ accelerometers (ActiGraph, LLC, Pensacola FL, USA) for seven days and completed both the SBAS and EVS at two different assessment periods (T1 and T2). Criterion validity was calculated using Spearman's rank order correlations between each questionnaire score and accelerometer-measured MVPA. Sensitivity, specificity, and positive and negative predictive values were calculated using accelerometer-measured MVPA as the criterion to determine the ability of each questionnaire to predict whether or not a participant was meeting the 2008 US PA Guidelines. Findings Spearman correlation coefficients between questionnaire scores and minutes of accelerometer-measured MVPA were low (EVS, r=0.27 at T1 and r=0.26 at T2; SBAS, r=0.10 at T1 and r=0.28 at T2) and not statistically significant (P's>0.05). The EVS had sensitivity, specificity, and negative and positive predictive values of 27, 89, 59, and 68% at T1 and 33, 74, 38, and 70% at T2, respectively. The SBAS had sensitivity, specificity, and negative and positive predictive values were 18, 79, 33, and 62% at T1 and 67, 58, 43, and 79% at T2. While both questionnaires may be useful in identifying AA women who do not meet the 2008 PA Guidelines, using the questionnaires to identify AA women meeting the PA Guidelines should be done with caution.