Background
Cardiovascular disease is a leading cause of morbidity and mortality in American adults.Reference Xu, Kochanek and Murphy 1 Behavioural risk factors for cardiovascular disease such as sedentary behaviours, poor diet, and tobacco use are typically initiated in youth and sustained through adulthood. In 2010, the American Heart Association (AHA) presented the goal of improving cardiovascular health of all Americans by 20% by addressing seven metrics of cardiovascular health: smoking status in the last 12 months, body mass index, levels of physical activity, dietary intake, blood pressure, cholesterol, and glucose.Reference Lloyd-Jones, Hong and Labarthe 2 The metrics are then stratified into ideal, intermediate, and poor cardiovascular health status. The validity of this “heart score” metric has been well established in adults, with 5–7 ideal metrics being associated with significantly lower levels of disease than those with 0–1 ideal metrics.Reference Folsom, Yatsuya and Nettleton 3 To date, the prevalence of ideal heart metrics has been examined in one national sample of adolescents.Reference Lloyd-Jones, Hong and Labarthe 2 We sought to add to this literature by examining the behavioural heart score metrics – smoking status in the last 12 months, body mass index, levels of physical activity, and dietary intake– in a sample of 9–12th grade students from a diverse metropolitan area.
Methods
Data from the 2011 Philadelphia Youth Risk Behavior Survey were used for this analysis. Sampling procedures and methodology are fully described elsewhere. 4 The survey is administered biennially using a multiple-choice, self-administered, paper-and-pencil format. Data from 805 high school students who provided complete data for all behavioural heart risk score questions were analysed.
The demographic variables age, gender, and race/ethnicity were examined. A behavioural heart risk score for each student reflecting risk associated with smoking, body mass index, physical activity, and dietary intake was derived from responses to a series of standard Youth Risk Behavior Survey questions and risk level was assigned using the three-tiered system of ideal, intermediate or poor risk (see Table 2). Smoking history was extracted from three questions assessing current use of cigarettes, use within the past year, and use ever.Reference Folsom, Yatsuya and Nettleton 3 Age- and gender-specific body mass index percentiles were computed from self-reported height and weight (kg/m2).Reference Kuczmarski, Ogden and Guo 5 Past-week days of ≥60 minutes of physical activity were classified into risk categories reflecting current national recommendations.Reference Strong, Malina and Blimkie 6 Dietary intake was estimated from past-week consumption of sugar-sweetened beverages, namely, soda, and fruits, and vegetables.Reference Fang, Yang and Hong 7 Responses to fruit and vegetable intake were converted to a daily average and dichotomised around achieving five servings-per-day; daily soda consumption (y/n) was also recorded.Reference Fang, Yang and Hong 7 , Reference Fung, Malik and Rexrode 8 A behavioural heart risk summary score of ideal reflected an ideal risk profile in each of the four subcategories; intermediate risk indicated at least one subcategory in the intermediate category and none in poor; poor overall heart risk indicated at least one sub-category classified at poor risk.Reference Folsom, Yatsuya and Nettleton 3
Analyses were conducted on weighted data using SAS, version 9.3 (SAS Institute Inc., Cary, North Carolina, United States of America). PROC SURVEY procedures were used to account for the complex sampling design. Taylor series linearisation was used to calculate sampling errors estimated from the primary sampling units and strata. Demographic characteristics and heart health metrics of the sample were summarised with descriptive statistics.
Results
Our sample of 805 students from grades 9–12 represents a population of ≈35 thousand diverse, urban adolescents. The majority of the participants were female (59%) and African American (51%).
Data on the four health metrics showed that most participants (89%) were in the ideal category for smoking and body mass index (66%). The majority was either in the intermediate (70%) or poor (24%) categories for physical activity, and 72% were in the intermediate category for healthy diet (Table 1).
Table 1 Composition and prevalence of behavioural heart risk score outcome measure.
Table 2 Behavioural cardiovascular health metrics by demographic characteristics.
Less than 1% of the sample (0.6%) had ideal, 49% had intermediate, and 50% had poor cardiovascular health. The mean cardiovascular health score for the entire sample was 2.50 (95% CI 2.45–2.54). No significant differences in cardiovascular health scores were observed by gender (p > 0.3008), whereas racial differences were observed. Specifically, Asian students had a significantly lower heart score as compared with those self-reporting as African American (M = 2.40 (2.32–2.49) versus M = 2.51 (2.46–2.56); p = 0.03) or mixed race/other groups (M = 2.40 (2.32–2.49) versus M = 2.56 (2.47–2.66); p = 0.01). Differences in mean heart health scores by age were also observed: heart scores increased by 0.33 (p < 0.04) as participants got older, indicating that poorer heart health was associated with increased age.
Discussion
Less than 1% of the 9–12th grade students surveyed achieved what we classified as “ideal” heart health based on the behavioural indices of body mass index, smoking status, diet, and physical activity. This very low percentage of ideal heart health in urban adolescents converges with one national study also showing that less than 1% of 12–19-year-olds achieved ideal heart health based on both behavioural and physiological assessments.Reference Shay, Ning and Daniels 9
From a school and public health perspective, these data should serve as a rallying cry. Risk for cardiovascular disease only increases with age while reversing sub-optimal physiological indicators of poor heart health, including high glucose levels, is atypical in adults.Reference Magnussen, Koskinen and Juonala 10 Loss of ideal heart health status in youth typically begins a trajectory of personal and health care system burden to manage and treat risk factors for cardiovascular disease: delaying this loss of “ideal” heart health in all school children should be considered a national priority in tandem with improving the heart health of the nation.Reference Fang, Yang and Hong 7 This is especially important considering that late adolescence is a time when many behavioural patterns are established.
Although these findings are based on self-report data and summarise only behavioural metrics of heart health, they nevertheless converge with national data showing that ideal heart health is a rarity in our youth. This reflects a critical health public health problem.
Financial Support
This project was supported in part by Temple University's Department of Public Health. Data collection was supported by a CDC ARREST grant to the School District of Philadelphia.
Conflicts of Interest
None.
Ethical Standards
Collection of this surveillance data was approved by Temple University's Institutional Review Board and the School District of Philadelphia; passive parental consent and student assent were obtained before survey administration.
Acknowledgements
The authors are indebted to the students, faculty and staff of the School District of Philadelphia for their support of data collection efforts and to Dr. Katherine W. Bauer, Assistant Professor at Temple University, for her input on the data analysis.
