ICH Metrics

In 2010, the AHA established the ICH metric.3 Seven health metrics have been established to define cardiovascular health—categorized as poor, intermediate, or ideal (Table 1, as seen in the Introduction). ICH is defined as meeting all 7 cardiovascular health metrics and the absence of cardiovascular disease or cardiovascular medication use. The 7 cardiovascular health metrics are split into 4 health behaviors (smoking status, physical activity, dietary patterns, and BMI) and 3 health factors (fasting total cholesterol, blood glucose, and blood pressure). Table 1 details specific definitions of poor, intermediate, and ideal cardiovascular health for children aged 12 to 19 years.

Definitions of Poor, Intermediate, and Ideal Cardiovascular Health According to AHA 2020 Goals: Health Behaviors and Risk Factors for Children 12 to 19 Years of Age^a

AHA indicates American Heart Association; BMI, body mass index; DBP, diastolic blood pressure; ellipses (···), data not available; PA, physical activity; SBP, systolic blood pressure.

Height was measured using a wall‐mounted stadiometer; weight was measured using a medical‐grade electronic scale. BMI was calculated and reported in kilograms per meter squared (kg/m²). Centers for Disease Control and Prevention definitions of sex‐ and age‐based BMI percentiles (2–20 years of age) were used.25 Study BMI categories were defined as the following: normal weight: BMI <85th percentile; overweight/obese: BMI 85th percentile to <1.2 times the 95th percentile, and severely obese: BMI ≥1.2 times the 95th percentile or BMI ≥35 kg/m².14 Seated blood pressures were taken using a manual sphygmomanometer, using an appropriately fitted cuff. Each participant sat quietly with legs uncrossed for 10 minutes before blood pressure measurement. Three consecutive blood pressure readings were taken at least 3 minutes apart. The average of the final 2 measurements was used. Fasting blood samples (>10 hours) were collected and total cholesterol, low‐density lipoprotein cholesterol, high‐density lipoprotein cholesterol, triglycerides, glucose, and insulin were measured using standard methods by the Fairview Diagnostics Laboratories, Fairview‐University Medical Center (Minneapolis, MN)—a Center for Disease Control and Prevention certified laboratory.

Dietary intake was measured using the Youth/Adolescent Questionnaire (YAQ), a semiquantitative food frequency questionnaire. The YAQ asks participants about dietary and supplement intake in the previous year.26, 27 General physical activity was assessed using a modified Godin Leisure‐Time questionnaire28, 29 that assessed (1) intensity (strenuous, moderate, mild) of physical activity in the previous week during free time, (2) participation in organized sports in the previous years, and (3) leisure time physical activity (at least 10 times in the previous year). Smoking exposure was evaluated by self‐report questionnaire as never, current, former, previous, or secondhand smoke exposure.

BMI categorization and total cholesterol, blood pressure, and glucose thresholds were consistent between the study instruments and ICH guidelines; therefore, no modifications were made to these variables. Current (n=2) and former smokers (n=5) were categorized as meeting the definition of poor ICH, whereas never smokers (n=293) were classified as meeting ICH. The modified Godin Leisure‐Time questionnaire assessed strenuous and moderate physical activity in the past week (times per week and minutes per session). Strenuous and moderate activity was defined as “heart beats rapidly” and “not exhausting,” respectively; both listed various activities that were relevant. For the ICH metric, we calculated minutes per day of moderate and vigorous physical activity using the following equation: (times per week×minutes per session)/7 days per week. The YAQ is a 152‐item food frequency questionnaire that collects a comprehensive assessment of food intake in the past week or month. We utilized 45 questions that met the specified Dietary Approaches to Stop Hypertension (DASH) food categories for the ICH guidelines: fruits/vegetables (n=30), whole grains (n=10), fish (n=2), sugar‐sweetened beverages (n=3), and salt intake (micronutrient analysis). Nearly all food questions assessed frequency of intake using the following, or similar, answer options: (1) never/less than 1 per month, (2) 1 to 3 per month, (3) 1 per week, (4) 2 to 4 times per week, and (5) 5 times per week. We calculated frequency of intake by taking the midpoint (ie, midpoint=2 servings per month if participant chose option #2 [1–3 per month]) or absolute value (ie, serving=1 if participant chose option #3 [1 per week]) reported. We then calculated the total servings per unit of time for each relevant ICH dietary subcomponent: fruits and vegetables (≥4.5 cups/d), whole grains (≥3 servings/d), fish (≥two 3.5‐oz servings/wk), sugar‐sweetened beverages (≤36 oz/wk), and salt (≤1500 mg/d) based on a 2000‐kcal/d diet. For example, for fruit and vegetable consumption, each participant's overall servings per day were a summary score of servings from the relevant 30 fruit/vegetable YAQ questions. This process was repeated for whole grains, fish, and sugar‐sweetened beverages. A summary salt intake was calculated using a proprietary micronutrient algorithm at the Harvard T.H. Chan School of Public Health Nutrition Department.