Associations Between the Physical Activity Vital Sign and Cardiometabolic Risk Factors in High-Risk Youth and Adolescents

Abstract

Background:

The physical activity vital sign (PAVS) is a simple, validated tool for assessing physical activity in adults that has not been previously studied in pediatrics.

Hypothesis:

Reported physical activity utilizing the PAVS in pediatric patients should vary according to known associations with physical activity, such as age, sex, blood pressure, and body mass index (BMI).

Study Design:

Cross-sectional study.

Level of Evidence:

Level 3.

Methods:

All patients within a family medicine residency clinic were assessed via the PAVS from October 1, 2015, to October 31, 2016, including 255 consecutive pediatric patients aged 5 to 18 years. Associations were examined between PAVS, age, sex, blood pressure, and BMI using 1-way analysis of variance.

Results:

The average PAVS reported for youth (5-11 years) was 384.9 ± 218.1 minutes per week, with 69.5% reporting sufficient physical activity (≥300 minutes per week). Adolescents (12-18 years) reported a mean PAVS of 278.3 ± 199.6 minutes per week, with 51.1% reporting sufficient physical activity. Physical activity was lower in older participants (P < 0.0001) and was higher in male patients (P < 0.03). Higher BMI was associated with lower PAVS (P < 0.005), while lower systolic blood pressure was associated with a greater number of days per week of physical activity (P < 0.005).

Conclusion:

The PAVS successfully identifies accepted associations between age, sex, and BMI in a pediatric population.

Clinical Relevance:

The correlation of the PAVS with age, sex, BMI, and blood pressure may inform future strategies to address and prevent cardiometabolic disease in pediatric patients.

Physical inactivity is a growing public health concern and the fourth leading cause of death worldwide.¹⁰ Inactivity contributes to numerous chronic diseases and carries a global economic burden of more than 50 billion dollars.⁵ Physical activity interventions in adult populations reduce cardiovascular disease risk^2,15,16 and cardiometabolic risk factors, including hypertension⁶ and hypercholesterolemia.⁹ The World Health Organization estimates that more than 80% of the world’s adolescent population is insufficiently active.²¹ Improved strategies for physical activity assessment and promotion in children are needed to combat noncommunicable diseases carried into adulthood.

Physical activity guidelines for Americans include a recommended 60 minutes of moderate to vigorous physical activity daily for youth and adolescents.¹ However, more than 80% of American adolescents do not meet these recommendations.¹⁸ Self-reported physical activity data from the 2015 Youth Risk Behavior Survey indicate that less than half of high school–aged adolescents meet physical activity guidelines.³ In the National Health and Nutrition Examination Survey (NHANES), only 42.5% of youth (6-11 years old) achieved 60 minutes of exercise daily.¹² A marked drop-off in physical activity above age 12 years was also found, where less than 7.5% of adolescents met physical activity goals.¹²

Utilization of an exercise or physical activity vital sign (PAVS) is a cost-effective, validated strategy for assessing physical activity in adults.^4,22 The introduction of a PAVS in the clinical setting offers a mechanism for clinicians to initiate a discussion with patients regarding their physical activity habits. Despite its ease of use, little research is available to support this recommendation and its effect on clinical outcomes, and no prior studies have evaluated the use of a PAVS in a pediatric population.^8,20 The purpose of this study was to evaluate the use of a PAVS in a pediatric population and determine its association with common markers of cardiometabolic disease.

Methods

Study Design and Participants

This study was approved by the institutional review board at Greenville Health System, Greenville, South Carolina.

This was a cross-sectional study of patients from a high-risk, residency-based family medicine clinic (Greenville Health System, Greenville, SC). The clinic population consists of approximately 4500 underserved patients, including 450 patients aged 0 to 18 years, (>99% Medicare, Medicaid, or uninsured) with a Milliman Advanced Risk Adjusters score of 5.24, indicating a high degree of medical complexity (normal = 1.0).

Data were obtained over a 13-month period from October 1, 2015, to October 31, 2016. Participants aged 5 to 18 years with at least 1 PAVS measurement were included in this investigation. Participants were classified as youth (5-11 years) or adolescent (12-18 years). In instances where multiple PAVS measurements were made, the most recent data point was utilized for analysis. Patients <5 or >18 years old were excluded.

Physical Activity Vital Sign

At the beginning of each clinic visit, the PAVS was determined by nursing staff (5 licensed practical nurses and 2 registered nurses) during intake and collection of traditional vital signs. Staff nurses received a brief orientation and instruction regarding collection of the PAVS during implementation preceding this study. The PAVS score is a product of the reported days per week (0-7) and average minutes per day (10-150) of at least moderate physical activity (activities such as brisk walking or dancing, approximately 3-6 metabolic equivalents) as described previously.⁴ This information is obtained as 2 questions in the electronic record and read verbally by the nurse to the patient or parent, utilizing a translator when necessary. The 2 questions are (1) “How many days per week do you perform moderate to strenuous exercise (like a brisk walk)?” and (2) “On average, how many minutes do you exercise per day?” Physicians were aware of the PAVS within the electronic record but were not instructed to alter their standard medical practice during this study.

Demographics

Age, race/ethnicity, and sex were obtained from the electronic medical record. Race/ethnicity are self-reported during the health care encounter.

Cardiometabolic Markers

Blood pressure and body mass index (BMI) were obtained routinely at each office visit. Blood pressure was taken according to recommended guidelines, with the patient sitting for at least 5 minutes and the use of a size-appropriate cuff. Hypertension was defined as a systolic or diastolic blood pressure greater than or equal to the 95th percentile per current guidelines.⁷ Height and weight were obtained in standard fashion without shoes but in clothing worn by the patient. Normal weight (<85th percentile), overweight (85th to 95th percentile), and obese (≥95th percentile) were defined by BMI according to current guidelines.¹¹ If multiple values were obtained during the study period, the most recent values were utilized in the analysis.

Analysis

Patients were categorized into 3 groups based on the reported PAVS: inactive (0 minutes per week), underactive (1-299 minutes per week), and active (≥300 minutes per week). Categorization was done based on current guidelines for physical activity in children and adolescents¹⁹ and to allow comparison with previously published studies utilizing a goal of 60 minutes at least 5 days per week. Since some prior studies have used a threshold of 7 days per week of physical activity, a PAVS of 420 minutes per week (60 minutes × 7 days) was also utilized for comparison. Patient factors (age, sex, BMI, and blood pressure) were examined using 1-way analysis of variance. Statistical analysis was completed using SPSS statistical software (Version 23.0; IBM Corp).

Results

Study Population

In total, 255 children and adolescents were included as participants in the study (see descriptive statistics in Table 1). Using the PAVS, participants reported a mean of 327.6 (SD, 214.7) minutes per week of exercise (Table 2).

Table 1.

Characteristics of study participants

Characteristic	n	%
Race
White/Caucasian	68	26.7
Black/African American	152	59.6
Hispanic	14	5.5
Other/unknown	21	1.6
Sex
Female	124	48.6
Male	131	51.4
Age, y
5-11	118	46.3
12-18	137	53.7
Body mass index
Normal weight (<85th percentile)	144	56.5
Overweight (85th to 95th percentile)	47	18.4
Obese (≥95th percentile)	64	25.1
Blood pressure
Normal	222	87.4
Hypertension (systolic or diastolic blood pressure ≥95th percentile)	32	12.6

Table 2.

Mean physical activity vital sign (PAVS) and distribution of participants by activity level

	Mean PAVS, min/wk	% Inactive (PAVS = 0)	% Underactive (PAVS = 1-299)	% Active (PAVS ≥300)	% Active (PAVS ≥420)
Total	327.6 ± 214.7	9.0	31.4	59.6	41.2
Age
Youth	384.9 ± 218.1	2.5	30.0	69.5	55.1
Adolescents	278.3 ± 199.6	14.6	34.4	51.1	29.2
Race/ethnicity
Black or African American	341.5 ± 229.9	7.9	27.0	65.1	42.1
White or Caucasian	313.2 ± 198.8	11.8	29.4	58.8	38.2
Hispanic	285.0 ± 140.1	7.1	42.9	50.0	42.9
Other or unknown	302.4 ± 179.0	9.5	38.1	52.4	42.9
Sex
Male	355.1 ± 236.1	11.5	22.9	65.6	48.9
Female	298.6 ± 186.0	6.5	40.3	53.2	33.1
Body mass index
Normal	357.0 ± 221.6	6.9	25.7	67.4	45.8
Overweight	338.2 ± 197.4	2.1	38.3	59.6	46.8
Obese	253.6 ± 195.6	18.8	39.1	42.2	26.6
Blood pressure
Normal	320.9 ± 216.0	9.0	32.0	59.0	37.8
Hypertensive	351.9 ± 164.7	9.4	28.1	63.0	62.5

PAVS and Age

The amount of self-reported physical activity declined with age (P < 0.0001) (Table 2). The reported mean PAVS for youth was 384.9 (SD, 218.1) and for adolescents 278.3 (SD, 199.6) minutes per week. A greater proportion of youth met the recommended 300 minutes per week of physical activity: 69.5% reported sufficient physical activity, 30.0% reported underactivity, and 2.5% reported as inactive. When compared with youth, the proportion of adolescents who reported adequate physical activity declined, with 51.1% reporting sufficient physical activity, 34.4% reporting underactivity, and 14.6% reporting inactivity. A total of 55.1% of youth and 29.2% of adolescents reported ≥420 minutes of physical activity per week

PAVS and Race/Ethnicity

No significant differences in physical activity were seen between race/ethnicity and PAVS (Table 2).

PAVS and Sex

Male participants reported more physical activity through the PAVS in youth and adolescents. Overall, boys reported about 1 hour per week or 19% more physical activity than girls (P = 0.03) (Table 2).

PAVS and Body Mass Index

The average BMI among participants was in the 70th percentile (69.9%; SD, 28.3%). Eighteen percent of patients were overweight and 25.1% were obese. Consistent with prior trends, a significant reduction in physical activity was seen among overweight and obese participants (P < 0.0001) (Table 2). Individuals with a normal bodyweight reported a mean PAVS of 357.0 (SD, 221.6), while obese individuals reported 253.6 minutes per week (SD, 195.6), a 29% reduction in physical activity (P < 0.005). Patients who reported sufficient physical activity were less likely to be overweight or obese compared with inactive and underactive individuals (P < 0.005). The BMI percentile was associated with the single question regarding minutes per day of exercise reported (P < 0.01), but not that regarding the number of days per week of exercise.

PAVS and Blood Pressure

No significant association was found between PAVS and systolic or diastolic hypertension (Figure 1). Of active patients, 13% had blood pressure values in the hypertensive range, similar to underactive (11.3%) and inactive (13.0%) patients (Table 2). In contrast to BMI, systolic blood pressure percentile (P < 0.005) and hypertension diagnosis (P = 0.02) were associated with the component question regarding number of days of exercise per week rather than the minutes per day of exercise.

Figure 1.

Association of age, body mass index, and blood pressure with the physical activity vital sign (PAVS). BMI, body mass index; DBP, diastolic blood pressure; SBP, systolic blood pressure.

Discussion

Physical inactivity is associated with high rates of cardiovascular disease, all-cause mortality, and several known malignancies. The World Health Organization estimates that at least 81% of adolescents worldwide and 72.6% of American adolescents are insufficiently active.⁹ In this study, only 41.2% of participants met the US Physical Activity Guidelines of at least 420 minutes per week. Strategies for increasing physical activity have the potential to markedly improve wellness in this high-risk population. In an era of population health where small groups of patients with high degrees of comorbid conditions are the highest utilizers of health care resources, effective strategies to reduce the burden of disease are greatly needed. Use of a physical activity or exercise vital sign has been championed in adult medicine, allowing providers to quickly assess physical activity and target those at greatest risk for further assessment and intervention, but this has not been evaluated in children.¹³

In this study, younger patients, male patients, and patients of healthy weight reported more physical activity. We found that physical activity self-reported as a vital sign aligns with national self-reported physical activity data in this age group from the Youth Risk Behavior Survey¹² and National Youth Fitness Survey¹ (Table 3). Self-reported physical activity in our study was higher than that measured by accelerometer (NHANES¹⁷), suggesting that self-report may overestimate physical activity. No significant differences in PAVS were found between ethnicities. It is unknown whether physical activity is equivalent across ethnicities or if reported similarity is due to differences in self-reporting between ethnic groups. While this is not unique to the pediatric population, the optimal way to obtain physical activity measures from pediatric patients and their families warrants further investigation.

Table 3.

Physical activity reported by the physical activity vital sign (PAVS) compared with prior published studies in youth and adolescents ^a

	PAVS	YRBS	NHANES	PAVS	YRBS	NYFS
	% Active (PAVS ≥300 or 60 min on ≥5 d/wk)			% Active (PAVS ≥420 or 60 min on ≥7 d/wk)
Youth	69.5		42.5	55.1		59.3
Adolescent	51.1	48.6	7.5	29.2	27.1	27.5

NHANES, National Health and Nutritional Examination Survey⁷; NYFS, National Youth Fitness Survey¹¹; YRBS, Youth Risk Behavior Survey.¹²

^aData obtained by self-report except for NHANES, where data were obtained by accelerometer.

The PAVS is intended to allow clinicians to identify at-risk individuals with low physical activity levels and subsequently provide physical activity interventions to prevent cardiometabolic diseases such as obesity and hypertension. The marked decline in physical activity from youth to adolescents represents an important area for public health concern, suggesting that focused interventions such as anticipatory guidance and physical activity counseling around ages 10 to 13 years may be valuable. Interestingly, while there was a significant decline in activity among obese individuals, overweight individuals report only 19 minutes per week less physical activity than normal-weight individuals. This may suggest that even minimal physical activity changes in targeted populations could help prevent progression toward obesity.

In total, 70% of youth meet physical activity goals, with a steep decline in adolescence where only 29% are sufficiently active. The decline in physical activity continues into adulthood where only 24.3% of adults in this population meet the lower physical activity recommendation for adults (150 minutes per week) and physical activity continues to decrease with older age.¹⁴ Targeting physical activity interventions to youth, prior to the decline in physical activity, may be an important area for the prevention of physical inactivity in children and adults.

When considering the individual questions in the PAVS and potential implications for future screening and physical activity recommendations, BMI and obesity better correlated with the minutes per day of reported exercise while blood pressure and hypertension better correlated with the days per week of exercise. There may be a loss of information in considering the PAVS as a total value in minutes per week rather than considering the individual questions separately. No single question or value successfully captured those at risk for both obesity and hypertension. These findings require larger studies and further investigation.

Proper understanding and consistent interpretation of the PAVS questions by patients contribute to the reliability of patient reporting, but this may be particularly challenging in younger patients. Revision of the correct wording for younger children should be considered. For example, moderate physical activity could be defined with age-appropriate activities and suitable language per educational level to facilitate patient understanding. Additional studies are needed to optimize the PAVS tool and implementation for use in youth and adolescents.

Limitations

This study draws from a small, high-risk pediatric population within a family medicine residency clinic, and thus findings may not be applicable to other clinical populations. Despite the small number of patients, the risk of cardiometabolic disease and declining physical activity with older age was high and likely represents a patient population that will benefit from physical activity intervention. While this study found an association of PAVS with obese and overweight patients, these data did not show an association of PAVS with hypertension. This is likely because of the small sample size or that only a single blood pressure value was included in the analysis. Larger studies are needed to investigate whether PAVS can identify young patients at risk for hypertension.

In addition, the PAVS tool captures at least moderate-intensity physical activity but does not query compliance with other components of the physical activity guidelines, including vigorous-intensity activity or strengthening activities. Total daily physical activity and light-intensity physical activity measures, associated with better health outcomes, are not captured by the PAVS and could factor in to the development of cardiometabolic disease.¹¹ Broader investigation of all physical activity components within a pediatric PAVS may prove to be a better predictor of health in children.

Conclusion

Pediatric physical activity declines significantly with age and drops dramatically between youth and adolescents. Declining physical activity is associated with an increase in the prevalence of obesity across age groups. The PAVS is a simple screening tool to assess physical activity and guide intervention that has been unexamined in pediatric populations.