Reproducibility of visit-to-visit variability of blood pressure measured as part of routine clinical care

Objectives: Secondary analysis of clinical trial data suggests visit-to-visit variability (VVV) of blood pressure is strongly associated with the incidence of cardiovascular disease. Measurement of blood pressure in usual practice settings may be subject to substantial error, calling into question the value of VVV in real-world settings. Methods: We analyzed data on adults of at least 65 years of age with diagnosed hypertension who were taking antihypertensive medication from the Cohort Study of Medication Adherence among Older Adults (n = 772 with 14 or more blood pressure measurements). All blood pressure measurements, taken as part of routine outpatient care over a median of 2.8 years, were abstracted from patients’ medical charts. Results: Using each participant's first seven SBP measurements, the mean intraindividual standard deviation was 13.5 mmHg. The intraclass correlation coefficient for the standard deviation based on the first seven and second seven SBP measurements was 0.28 [95% confidence interval (CI) 0.20–0.34]. Individuals in the highest quintile of standard deviation of SBP based on their first seven measurements were more likely to be in the highest quintile of VVV using their second seven measurements (observed/expected ratio = 1.71, 95% CI 1.29–2.22). Results were similar for other metrics of VVV. The intraclass correlation coefficient was lower for DBP than SBP. Conclusion: These data suggest VVV of SBP measured in a real-world setting is not random. Future studies are needed to assess the prognostic value of VVV of SBP assessed in routine clinical practice.visit-to-visit variabilit

Objectively Measured Physical Activity in Sixth-Grade Girls

Objectives - To describe the objectively-measured physical activity (PA) characteristics of a diverse sample of 6th grade girls to examine influences on PA, and to report compliance with PA guidelines. Design - Cross-sectional study. Setting - Six locations across the United States. Participants - 1578 6th grade girls. Actigraph accelerometers were worn for 7 days, and data for 6 days were included in the analyses. Main exposure - Race/ethnicity, free-or-reduced price lunch (FRPL), and geographic region. Main outcome measure - Six operational definitions of adequate activity (60 min or 30 min of daily MVPA at or above 4.6, 3.8 or 3.0 METS (metabolic equivalents)) were applied to examine whether girls met physical activity guidelines. Results - Average time spent in sedentary, light, moderate, and vigorous activities was 460, 342, 18, and 6 min/day, respectively. White girls were more active than girls in other race/ethnic groups, and girls who did not receive FRPL were more active than girls who did. Girls in western states were most active. Percentages of girls in compliance with the 6 thresholds for adequate activity varied widely, and ranged from 0.6% to 99.8%. Conclusions - When physical activity is measured objectively and a 4.6 MET cupoint for MVPA is applied, most 6th grade girls fall below guidelines for adequate physical activity. One notable finding was the impact of different accelerometer scoring protocols on estimates of compliance. Conceptual and empirical work is needed to define appropriate physical activity for youth using objective physical activity measures

Objectively Assessed Associations between Physical Activity and Body Composition in Middle-School Girls: The Trial of Activity for Adolescent Girls

Declining levels of physical activity probably contribute to the increasing prevalence of overweight in US youth. In this study, the authors examined cross-sectional and longitudinal associations between physical activity and body composition in sixth- and eighth-grade girls. In 2003, girls were recruited from six US states as part of the Trial of Activity for Adolescent Girls. Physical activity was measured using 6 days of accelerometry, and percentage of body fat was calculated using an age- and ethnicity-specific prediction equation. Sixth-grade girls with an average of 12.8 minutes of moderate-to-vigorous physical activity (MVPA) per day (15th percentile) were 2.3 times (95% confidence interval: 1.52, 3.44) more likely to be overweight than girls with 34.7 minutes of MVPA per day (85th percentile), and their percent body fat was 2.64 percentage points greater (95% confidence interval: 1.79, 3.50). Longitudinal analyses showed that percent body fat increased 0.28 percentage points less in girls with a 6.2-minute increase in MVPA than in girls with 4.5-minute decrease (85th and 15th percentiles of change). Associations between MVPA in sixth grade and incidence of overweight in eighth grade were not detected. More population-based research using objective physical activity and body composition measurements is needed to make evidence-based physical activity recommendations for US youth

Relationships among Fitness, Body Composition, and Physical Activity

This study was designed to examine the associations of physical activity and body composition with cardiorespiratory fitness in eighth grade girls

Age-Related Change in Physical Activity in Adolescent Girls

Purpose - To determine the annual rate at which physical activity changes in girls during middle school using both objective and self-report measures of physical activity. Methods - Participants were 6th and 8th grade girls from the control schools in the Trial of Activity for Adolescent Girls (TAAG). Random cross-sectional samples initially were drawn from 6th grade girls (n=786) and two years later from 8th grade girls (n=1545). A cohort of 501 girls was in both the 6th and 8th grade samples. The girls wore an accelerometer for six days and completed the 3-Day Physical Activity Recall (3DPAR). Data were summarized using 3.0-4.6- and 6.5-MET cutpoints for accelerometry and self-reported physical activity. Analyses were performed using repeated measures ANOVA in PROC MIXED. Results - More than 40% of the girls were White, approximately 20% were African-American, and 20% were Hispanic. The annual percent decrease in physical activity in the cross-sectional sample was approximately 4% (-1.76 min MVPA/day), using accelerometer data. The percent decrease in physical activity based on self-report data was higher, 6-13%, depending on the physical activity variable. Declines tended to be larger in African-American girls, but the ethnic differences were not statistically significant. Conclusions - Based on comparisons of cross-sectional samples of 6th and 8th grade girls, objectively-measured physical activity declined at a rate of 4% per year

A Longitudinal Study of Sedentary Behavior and Overweight in Adolescent Girls

To examine sedentary and light activity in relation to overweight in adolescent girls

Promoting Physical Activity in Middle School Girls: Trial of Activity for Adolescent Girls

Background - Physical activity is important for weight control and good health; however, activity levels decline in the adolescent years, particularly in girls. Design - Group randomized controlled trial. Setting/participants - Middle school girls with English-speaking skills and no conditions to prevent participation in physical activity in 36 schools in six geographically diverse areas of the United States. Random, cross-sectional samples were drawn within schools: 6th graders in 2003 (n=1721) and 8th graders in 2005 (n=3504) and 2006 (n=3502). Intervention - A 2-year study-directed intervention (fall 2003 to spring 2005) targeted schools, community agencies, and girls to increase opportunities, support, and incentives for increased physical activity. Components included programs linking schools and community agencies, physical education, health education, and social marketing. A third-year intervention used school and community personnel to direct intervention activities. Main outcome measures - The primary outcome, daily MET-weighted minutes of moderate-to-vigorous physical activity (MET-weighted MVPA), was assessed using accelerometry. Percent body fat was assessed using anthropometry. Results - After the staff-directed intervention (pre-stated primary outcome), there were no differences (mean=-0.4, 95% CI=-8.2 to 7.4) in adjusted MET-weighted MVPA between 8th-grade girls in schools assigned to intervention or control. Following the Program Champion-directed intervention, girls in intervention schools were more physically active than girls in control schools (mean difference 10.9 MET-weighted minutes of MVPA, 95% CI=0.52-21.2). This difference is about 1.6 minutes of daily MVPA or 80 kcal per week. There were no differences in fitness or percent body fat at either 8th-grade timepoint. Conclusion - A school-based, community-linked intervention modestly improved physical activity in girls

The Effect of a Physical Activity Intervention on Bias in Self-Reported Activity

A positive outcome in self-reported behavior could be detected erroneously if an intervention caused over-reporting of the targeted behavior. Data collected from a multi-site randomized trial were examined to determine if adolescent girls who received a physical activity intervention over-reported their activity more than girls who received no intervention

A Cross-Sectional and Longitudinal Study of Travel by Walking Before and After School Among Eighth-Grade Girls

To examine “travel by walking” (TBW) before and after school among eighth grade girls