VALIDITY & RELIABILITY OF PHYSICAL ACTIVITY SCREENING TOOLS FOR ADOLESCENTS IN PRIMARY CARE SETTINGS

1424 The purpose of the current study was to evaluate brief measures of vigorous (VPA) and moderate (MPA) physical activity that can be used in primary care settings with adolescents. The measures are designed to be brief enough to be practical, yield clinically useful scores and assess targeted behaviors. Each measure has two items that are averaged: frequency of physical activity for past 7-days and for a typical week. To meet criterion, VPA must be done for 20-mins or more at least 3 days a week (USDHHS, 1991). For MPA, 60-mins must be accumulated in bouts of 10-mins throughout the day on at least 5 days (Biddle, Sallis, & Cavill, 1998). Test-retest reliability was assessed with 250 6th-12th graders in San Diego and Pittsburgh (age X=14.6, 55% female, 36% Caucasian). Intraclass correlation coefficients were 0.76 and 0.77 for VPA and MPA respectively. Concurrent validity was assessed with 60 adolescents (age X=13.8, 65% female, 35% Caucasian). Criterion measure was 7-day CSA accelerometer data. VPA and MPA were calculated from the CSA data using previously developed cut-points. Correlations for self-reports with CSA data were 0.48 and 0.29 for VPA and MPA (p<0.05). Sensitivity of the measures to detect subjects not meeting VPA and MPA guidelines, were 36% and 71%. Specificity was 100% for VPA, but 21% for MPA. Subjects were found to over-report VPA by 3.82 days/wk and MPA by 0.03. The current study provides scientific support for the utility and relative validity of these tools, although diagnostic accuracy is limited. Supported by the American Cancer Society