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Adolescent assessment of cardiovascular heart disease risk factor attitudes and habits
JOURNAL OF ADOLESCENT HEALTH 2004;35:374 –379
ORIGINAL ARTICLE
Adolescent Assessment of Cardiovascular Heart Disease Risk Factor Attitudes and Habits STEPHEN E. SMALLEY, D.O., ROBERT R. WITTLER, M.D., AND RUTH H. OLIVERSON, A.R.N.P.
Purpose: To assess the attitudes of adolescents regarding cardiovascular heart disease risk factors and determine their potential influence on reported habits: exercise, smoking, and diet, as well as their body mass index (BMI). Methods: Surveys were distributed to 141 male and 207 female adolescents at two clinic sites that serve a mostly Medicaid or uninsured population. Attitudes for obesity, smoking, and high fat diet were assessed with Likert scales, and habits for exercise, smoking, and fast food consumption were self-reported. Height and weight data were collected as well. Univariate modeling was accomplished with Spearman’s rank correlation coefficients, contingency table analysis, and ANOVA. Logistic regression was used for multivariate modeling. Results: The majority of participants agreed that obesity, smoking, and high fat diets may lead to heart disease. Fifty percent of the population exercised three times or less a week. Reported smoking was similar to national averages and increased with age. Participant attitudes were disparate to their reported habits. Occurrence of obesity in the sample was higher than national averages. Smokers, compared with nonsmokers, were 1.9 times as likely to be overweight or obese (p ⴝ .05). Participants who had a parent/guardian or grandparent with a history of heart attacks were 2.7 times as likely to smoke (p ⴝ .001). Conclusion: Adolescents possess knowledge of cardiovascular risk factors as reflected in their attitude assessments; however, their lifestyle choices contradict these beliefs. © Society for Adolescent Medicine, 2004 From the Department of Pediatrics, University of Kansas School of Medicine-Wichita, Wichita, Kansas (S.E.S., R.R.W.), Wesley Clinics, Wichita, Kansas (S.E.S., R.R.W.), and Sedgwick County Health Department, Wichita, Kansas (S.E.S., R.R.W., R.H.O.). Address correspondence to: Dr. Stephen Smalley, 2503 Timber Crest Lane, Highland Village, TX 75077. E-mail: [email protected] Manuscript accepted January 16, 2004. 1054-139X/04/$–see front matter doi:10.1016/j.jadohealth.2004.01.005
KEY WORDS:
Heart disease Attitudes Beliefs Habits Lifestyle Smoking Obesity Adolescents
Although there is a large body of evidence regarding the effectiveness of lifestyle and dietary modification in preventing cardiovascular heart disease (CHD), obesity and smoking continue to be major problems in adolescence. Although the prevalence of smoking in high school has declined since 1997, the National Youth Tobacco Survey (NYTS) showed tobacco usage to be approximately 15% in middle school and 34% in high school [1]. NYTS also found that 80% of smokers began the habit before 18 years of age. Obesity, conversely, is on the rise with the prevalence of adolescents above the 95th percentile in body mass index (BMI) doubling over the past 20 years [2]. Aside from dietary choices, sedentary lifestyles [3], such as television viewing [4], contribute to obesity, owing to reduced energy expenditure and a propensity for increased dietary intake of high calorie snacks. Individual attitudes and beliefs regarding cardiovascular disease risk factors have been studied in the past. Silagy et al found that 45% of obese adults recognized their dietary habits to be harmful, and 75% of smokers recognized their smoking to be harmful [5]. In those individuals, nearly all of them wanted to improve, but only half of them made an © Society for Adolescent Medicine, 2004 Published by Elsevier Inc., 360 Park Avenue South, New York, NY 10010
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attempt to do so. Avis et al showed similar results in which adult participants were asked open-ended questions to identify behaviors that would make heart disease or stroke less likely [6]. The results showed that there was high knowledge of risk factors, but when asked about personal habits, knowledge was not associated with lower risk behaviors. Frost surveyed risk factor knowledge in college students and found that almost all of them were able to identify hypertension, smoking, high cholesterol, and low exercise as risk factors [7], however, 16% reported that they smoked cigarettes, 33.5% of them exercised regularly, and 32.9% of them had their cholesterol levels checked. Behera et al assessed attitudes of low-income African-American women [8]. Those surveyed had a low awareness of the prevalence of cardiovascular disease, and they identified stress as being the most important risk factor. They further identified the media as an important source for health information as well as misinformation. Data from the 1990 U.S. Bureau of the Census showed that teenagers in neighborhoods with low income, education, and house values with high levels of poverty had poorer dietary habits and less physical activity than those living in higher socioeconomic status (SES) neighborhoods [9]. We assessed the attitudes and health habits regarding cardiovascular heart disease risk factors, as well as whether or not an adolescent’s attitude about cardiovascular disease had any relationship to their health habits. Secondary goals of the study included the relationship of BMI to habits and beliefs, as well as to family history of heart attack.
Methods The participants were youths aged 13 to 18 years who visited one of the clinic sites for routine or acute health care in Wichita, Kansas from June 2002 to February 2003. The sites included the University of Kansas pediatric resident continuity clinic and the Teen Health Station of the Sedgwick County Health Department. The reimbursement to the continuity clinic consists of 75% Medicaid, 10% no insurance, and 15% private insurance. The Teen Health Station serves patients of whom 31% have Medicaid; 44%, no insurance; 17%, private insurance; 8%, unknown. Adolescents that agreed to participate in the study had weight and height measured, and then they completed the survey in a room separate from their parents. There were English and Spanish versions of the survey. The surveyor recorded height and
375
weight, and then left the room to allow the participant to complete the survey in privacy. The questionnaire asked for age, gender, and ethnicity. The next section included health habits: how many times a week did they participate in exercise that made them breathe hard and sweat for at least 20 minutes at a time, how many cigarettes had they smoked per day, and how many times per week had they eaten a meal from a fast food restaurant or a vending machine. Twenty-minute sustained exercise sessions reported on a per-week basis is considered by some to be a minimally acceptable duration for exercise [10 –12]; others accept 30 minutes as standard [13]. Exercise bouts that induce sweating have been found to provide a simplified way of reporting exercise intensity with cardiovascular health benefits [14]. Smoking was reported on a daily basis for ease of estimation for the participants. A binomial variable was created stratifying participants into smoking and nonsmoking groups. Nielsen and Popkin report from the Continuing Survey of Food Intake for Individuals: 1977 to 1996 (CSFII) an increasing trend in portion size that may result from “value adding” [15]. The same body of data shows increased consumption of pizza, cheeseburgers, and french fries, in addition to sugared beverages [16]. Vending machines were included in this assessment because of their increased appearance on school campuses in the recent past and the high calorie, low nutrition, and high fat items that they sell [17,18]. Therefore, it was felt that fast food and vending machine food consumption would be a reasonable approximation of high calorie, high fat food consumption, while keeping the survey brief. The next section asked the participant to rate their attitudes about cardiovascular heart disease risk factors on a 5-point Likert scale, ranging from “strongly disagree” to “strongly agree.” This section contained three statements: being overweight may cause heart disease, smoking cigarettes may cause heart disease, and eating a high fat diet may cause heart disease. The American Heart Association has identified these as modifiable risk factors for the development of cardiovascular heart disease [19]. The final section asked the participant whether or not they had knowledge that a parent, guardian, or grandparent sustained a heart attack. Whether or not a parent accompanied the participant to the clinic visit was also recorded on the survey, as it was felt to be a possible confounding variable. Descriptive statistics were derived for each of the survey variables. Binomial variables were created for categorizing individuals with a BMI ⬍ the 85th
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percentile vs. those with a BMI ⱖ the 85th percentile (overweight or obese) [20], as well as for whether or not a parent, guardian, or grandparent had a history of heart attack. Ages were combined into the following groups: 13- and 14-year-olds, 15- and 16-yearolds, and 17- and 18-year-olds. Responses to the habit and attitude questions were stratified by age group. Correlations between the attitude and habit responses were assessed by Spearman’s rank correlation test because the attitude responses were felt to be ordinal variables rather than continuous variables. Contingency table analysis was used for univariate categorical variable significance testing. Logistic regression modeling was developed for multivariate modeling of binomial variables (i.e., overweight or obese vs. nonobese and smokers vs. nonsmokers) to obtain odds ratios (OR). Model building was based on the principles developed by Hosmer and Lemeshow [21]. Statistical significance was defined as a p value ⱕ .05. The Institutional Review Board at Wesley Medical Center in Wichita and the University of Kansas School of MedicineWichita approved the survey. A formal collaborative agreement was made with the Sedgwick County Health Department Teen Health Station.
Results The demographics of the participants are listed in Table 1. The percentage of participants with BMI ⱖ the 85th and 95th percentiles (Table 2) is larger than those reported in the National Health and Nutritional Examination Surveys III, which was 21.7% and 12.8% for those at or above the 85th and 95th percentiles for boys, and 21.2% and 8.8% in girls, respectively [2]. The habit and attitude assessment is found in Table 3. Fast food and vending machine food consumption increased with age (p ⬍ .001), but there was not a statistically significant relationship between the reporting of exercise amount per week and age. Frequency distribution of exercise amount shows close to half of the population reporting three sustained exercise sessions per week or less (Figure 1). Frequency of smoking increased with age (Figure 2). The percentage of smokers in this survey was comparable with national averages [1]. Three-fourths of the 17- and 18-year-olds agreed with all three risk factors, and “strongly agree” was the most common attitude response (Figure 3). Participant attitudes were disparate to their reported habits.
JOURNAL OF ADOLESCENT HEALTH Vol. 35, No. 5
Table 1. Characteristics of Population (N ⫽ 348) Characteristic
Percent of Total
Age Mean (years) 13- and 14-year-olds 15- and 16-year-olds 17- and 18-year-olds Gender Male Female Race White Black Hispanic Asian Other BMI (kg/m2) Males Females 13- and 14-year-olds 15- and 16-year-olds 17- and 18-year-olds Site KU Continuity Clinic Teenage Health Station Parents present at visit Yes No Known relative that sustained heart attack No or don’t know Grandparent Parent/guardian Both parent/guardian and grandparent Language of Survey English Spanish
15.3 112 (32) 147 (42) 89 (26) 141 (41) 207 (59) 115 (33) 118 (34) 98 (28) 3 (1) 14 (4) 24.2 24.4 23.6 24.5 25.0
SD SD SD SD SD
⫾ ⫾ ⫾ ⫾ ⫾
5.2 6.2 5.8 6.0 5.9
53 (15) 295 (85) 175 (50) 173 (50) 225 (65) 101 (29) 12 (3) 10 (3) 329 (95) 19 (5)
Adjusted odds ratios derived from a multivariate logistic regression model with an outcome variable of being overweight or obese showed gender and
Table 2. Percentages of Population at or Above the 85th and 95th Percentiles for Age-appropriate Body Mass Index (BMI)
13- and 14-year-olds Male Female 15- and 16-year-olds Male Female 17- and 18-year-olds Male Female
Greater than or equal to the 85th percentile for BMI (%)
Greater than or equal to the 95th percentile for BMI (%)
34 51 39 38 45 35 40 52 35
25 24 26 23 25 22 19 28 15
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377
Table 3. Report of Attitude and Habits Attitudes 1 ⫽ SD; 2 ⫽ D; 3 ⫽ DN; 4 ⫽ A; 5 ⫽ SA Attitude Overweight 13- and 14-year-olds 15- and 16-year-olds 17- and 18-year-olds Smoking 13- and 14-year-olds 15- and 16-year-olds 17- and 18-year-olds High fat diet 13- and 14-year-olds 15- and 16-year-olds 17- and 18-year-olds a
Habits
Mode
Agreea (%)
3 4 5
48 68 76
5 5 5
73 80 76
3 3 5
46 59 74
Habit Exercise per week 13- and 14-year-olds 15- and 16-year-olds 17- and 18-year-olds Smoking per day 13- and 14-year-olds 15- and 16-year-olds 17- and 18-year-olds Fast food per week 13- and 14-year-olds 15- and 16-year-olds 17- and 18-year-olds
Mean (S.D.) 3.3 (⫾ 2.3) 2.8 (⫾ 2.6) 3.1 (⫾ 3.0) 0.1 (⫾ 1.0) 1.0 (⫾ 2.9) 3.4 (⫾ 6.2) 2.0 (⫾ 2.0) 2.5 (⫾ 2.1) 3.5 (⫾ 3.4)
SD ⫽ Strongly Disagree, D ⫽ Somewhat Disagree, DN ⫽ Don’t Know, A ⫽ Somewhat Agree, and SA ⫽ Strongly Agree. Percentage of those that either somewhat agree or strongly agree.
smoking to be statistically significant. The OR for males compared with females being obese or overweight was 1.66 (95% CI 1.1–2.6, p ⫽ .03) and the OR for smokers compared with nonsmokers was 1.90 (95% CI 1.0 –3.4, p ⫽ .05). Multivariate logistic regression modeling also showed age (p ⬍ .001) and a history of a parent, guardian, or grandparent having a heart attack (p ⫽ .001) to be significantly related to an outcome variable of smoking vs. nonsmoking. With age included as a covariate, the odds of being a smoker were 2.7 times greater (OR 95% CI 1.5– 4.9) for those individuals surveyed who reported a parent/guardian or grandparent having a heart attack.
Limitations
tutes an average amount of fast food per week. Even when vending machine food is included in the question, it still does not account for high fat, high salt, low fiber foods obtained as a la carte choices in school cafeterias or at home. A better question may have focused on the hours of television and computer usage per week, of which national averages have been reported [22]. The wording of the smoking habit question may have yielded results that were falsely low. Instead of reporting smoking behavior on a daily basis, the question could have asked about smoking on a weekly basis.
Discussion
The “fast food” question was a weakness of the survey. There is no reference value for what consti-
The hope from a public health perspective would be that all participants agree with the three statements regarding cardiovascular heart disease, and the ma-
Figure 1. Report of exercise and fast food intake. Participants were asked to report how many times they exercised per week. An exercise session was considered an activity of at least 20 minutes in which the participant breathed hard and sweated. Fast food intake also included meals from a vending machine. Intake was also reported for a per week basis.
Figure 2. Report of smoking by age group.
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JOURNAL OF ADOLESCENT HEALTH Vol. 35, No. 5
Figure 3. Attitude assessment of cardiovascular heart disease risk (CHD) risk factors by age groups.
jority usually did, especially in the older age groups. All age groups in the survey agreed that smoking was an important cause of cardiovascular heart disease, however only the older-aged participants were able to identify obesity and high fat diet as contributors. This suggests that younger adolescents are already aware of the hazards of smoking, whereas the cardiovascular impact of obesity and poor diet aren’t learned until they are older. Participant habits were in contradiction to these beliefs. The most important inconsistency was between the attitudes and habits regarding cigarettes. One-third of 17- and 18-year-olds smoked, despite three-fourths of the group acknowledging its role in cardiovascular heart disease. This survey showed a greater frequency of overweight and obese individuals as compared with national averages. There are a number of possible reasons to account for this. The reference data come from the National Health and Nutrition Examination Survey (NHANES III), which is over 10 years old. The Bogalusa Heart Study was a longitudinal study from 1973 to 1994 that observed an increased weight of 5.7 kg in 15- to 17-year-olds in this time period, with most of the rise occurring over the last 10 years of the survey [23]. Preliminary analysis from the NHANES IV, which covers 1999 to 2000, also reflects this trend: 15% of 12- to 19-year-olds are at or above the 95th percentile for BMI, which reflects a 4% increase from NHANES III [24]. Another reason for the disparity could stem from the fact that the majority of participants in this survey came from families of lower socioeconomic status; however, relationships between socioeconomic status and obesity have been difficult to establish [25], particularly in males and in ethnicities other than white [26].
There was a statistically significant relationship between smoking and BMI. Participants who smoked were 1.9 times more likely to be overweight or obese. The data may have identified a subpopulation of adolescents that will enter adulthood with two modifiable risk factors for cardiovascular heart disease. When the participants reported a heart attack occurring in either a parent/guardian or grandparent, they were 2.7 times more likely to be smokers, even when age was controlled for in a multivariate model. The data suggest that having a relative with a heart attack is not a deterrent to smoking, but may actually prove to be a risk factor for smoking in adolescents. The reporting of a “heart attack” may be a surrogate marker for a family history of smoking. Other studies have suggested that parental smoking may influence adolescents to smoke [27,28]. Adolescents possess accurate knowledge of cardiovascular heart disease risk factors as reflected in their attitude assessments; however, these attitudes appear to have no relationship to their lifestyle choices. This observation has substantial implications for the health care professional. The adverse lifestyle choices made by adolescents cannot be attributed to lack of knowledge. Motivation to make positive changes in health habits is, therefore, the goal. This lack of patient motivation was perceived as the number one barrier by pediatricians against the successful treatment of overweight children [29]. However, one study found teenagers to be receptive to preventive counseling by a health care professional with regard to diet, exercise, smoking, and alcohol [30]; the impact on health habits from this 20-minute counseling session was small, but significant. A question that needs to be posed, then, is how
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much more significant a change could be made if the counseling was coming from the adolescent’s own physician? Prevention should be the main focus for health professionals. Habits learned in childhood and adolescence carry over into adulthood, where they will be more difficult to change. The knowledge of cardiovascular disease risk factors does not influence the health behaviors of adolescents, therefore, the challenge to the health care professional will be to both educate and motivate changes in health habits. We thank Katherine Melhorn, M.D., Brian DeBrot, M.D., and Phillip Allen, M.D., Ph.D. for help with development of the project, as well as Mary Jane Whitehair, A.R.N.P., Mark Harrison, M.D., Beverly Dean, Jill Burke, Virginia Parker, Denice Maness, Mary Ann Bauersfield, P.A.-C., Megan Langston, and Melissa Winter-Foss for their contributions.
13.
14.
15. 16.
17.
18.
19.
References 1. Youth tobacco surveillance—United States, 2000. MMWR CDC Surveill Summ 2001;50:1– 84.
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2. Styne D. Childhood and adolescent obesity: Prevalence and significance. Pediatr Clin North Am 2001;48:823–54.
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3. Rosenbaum M, Leibel R. The physiology of body weight regulation: Relevance to the etiology of obesity in children. Pediatrics 1998;101:525–39.
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4. Robinson T. Reducing children viewing to prevent obesity: A randomized controlled trial. JAMA 1999;282:1561–7.
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5. Silagy C, Muir J, Coulter A, et al. Cardiovascular risk and attitudes to lifestyle: What do patients think? BMJ 1993;306: 1657–60. 6. Avis NE, McKinlay JB, Smith KW. Is cardiovascular risk factor knowledge sufficient to influence behavior? Am J Prev Med 1990;6:137–44. 7. Frost R. Cardiovascular risk modification in the college student: Knowledge, attitudes, and behaviors. J Gen Intern Med 1992;7:317–20. 8. Behera SK, Winkleby MA, Collins R. Low awareness of cardiovascular disease among low-income African-American women. Am J Health Promot 2000;14:301–5. 9. Lee R, Cubbin C. Neighborhood context and youth cardiovascular health behaviors. Am J Public Health 2002;92:428 –36. 10. Jakici JM. Effects of intermittent exercise and use of home exercise equipment on adherence, weight loss, and fitness in overweight women: a randomized trial. JAMA 1999;282:1554 – 60.
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11. U.S. Department of Health and Human Services. Healthy People 2010 (conference edition in 2 volumes). Washington, DC: U.S. Department of Health and Human Services, 2000. 12. U.S. Department of Health and Human Services. Physical Activity and Health: A Report of the Surgeon General. Atlanta, GA: U.S. Department of Health and Human Services,
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Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, 1996. Pate PR, Pratt M, Blair SN, et al. Physical activity and public health: A recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA 1995;273:402–7. Washburn RA. Physical activity assessment for epidemiologic research: the utility of two simplified approaches. Prev Med 1987;16:636 –46. Nielsen SJ, Popkin BM. Patterns and trends in food portion sizes, 1977–1998. JAMA 2003;289:450 –3. Nielsen SJ, Siega-Riz AM, Popkin BM. Trends in energy intake in U.S. between 1977 and 1996: Similar shifts seen across age groups. Obes Res 2002;10:370 –8. Harnack L, Snyder P, Story N, et al. Availability of a la carte food items in junior and senior high schools: A needs assessment. J Am Diet Assoc 2000;100:701–3. Story M, Hayes M, Kalina B. Availability of foods in high schools: Is there cause for concern? J Am Diet Assoc 1996;96: 123–6. Williams CL. Cardiovascular health in childhood: A statement for health professionals from the Committee on Atherosclerosis, Hypertension, and Obesity in the Young (AHOY) of the Council on Cardiovascular Disease in the Young, American Heart Association. Circulation 2002;106:143–60. Centers for Disease Control. Growth charts: United States Advance Data. 2000; 314. Hosmer DW, Lemeshow S. Model-building strategies and methods for logistic regression. In: Hosmer DW, Lemeshow S (eds). Applied Logistic Regression, 2nd edition. New York, NY: John Wiley & Sons, 2000:91–142. Academy of Pediatrics Committee on Communications. Children, adolescents, and television. Pediatrics 1990;85:1119 –20. Freedman DS, Srinivasan SR, Valdes RA. Secular increases in relative weight and adiposity among children over the last two decades: The Bogalusa Heart Study. Pediatrics 1999;99: 420 –6. National Center for Health Statistics. Prevalence of overweight among children and adolescents: United States, 1999. Available at: http://www.cdc.gov/nchs/products/pubs/ pubd/hestats/overwght99.htm. Accessed June 4, 2003. Sobal J, Stunkard AJ. Socioeconomic status and obesity: a review of the literature. Psychol Bull 1989;105:260 –75. Crawford PB. Ethnic issues in the epidemiology of childhood obesity. Pediatr Clin North Am 2001;48:855–78. Woodruff SI, Candelaria JI, Laniado-Laborin R, et al. Availability of cigarettes as a risk factor for trial smoking in adolescents. Am J Health Behav 2003;27:84 –8. Noland MP, Kryscio RJ, Hinkle J, et al. Relationship of personal tobacco-raising, parental smoking, and other factors to tobacco use among adolescents living in a tobacco-producing region. Addict Behav 1996;21:349 –61. Story MT, Neumark-Stzainer DR, Sherwood NE, et al. Management of child and adolescent obesity: Attitudes, barriers, skills, and training needs among health care professionals. Pediatrics 2002;110:210 –4. Walker Z, Townsend J, Oakley L, et al. Health promotion for adolescents in primary care: Randomised controlled trial. BMJ 2002;325:524 –9.
ORIGINAL ARTICLE
Adolescent Assessment of Cardiovascular Heart Disease Risk Factor Attitudes and Habits STEPHEN E. SMALLEY, D.O., ROBERT R. WITTLER, M.D., AND RUTH H. OLIVERSON, A.R.N.P.
Purpose: To assess the attitudes of adolescents regarding cardiovascular heart disease risk factors and determine their potential influence on reported habits: exercise, smoking, and diet, as well as their body mass index (BMI). Methods: Surveys were distributed to 141 male and 207 female adolescents at two clinic sites that serve a mostly Medicaid or uninsured population. Attitudes for obesity, smoking, and high fat diet were assessed with Likert scales, and habits for exercise, smoking, and fast food consumption were self-reported. Height and weight data were collected as well. Univariate modeling was accomplished with Spearman’s rank correlation coefficients, contingency table analysis, and ANOVA. Logistic regression was used for multivariate modeling. Results: The majority of participants agreed that obesity, smoking, and high fat diets may lead to heart disease. Fifty percent of the population exercised three times or less a week. Reported smoking was similar to national averages and increased with age. Participant attitudes were disparate to their reported habits. Occurrence of obesity in the sample was higher than national averages. Smokers, compared with nonsmokers, were 1.9 times as likely to be overweight or obese (p ⴝ .05). Participants who had a parent/guardian or grandparent with a history of heart attacks were 2.7 times as likely to smoke (p ⴝ .001). Conclusion: Adolescents possess knowledge of cardiovascular risk factors as reflected in their attitude assessments; however, their lifestyle choices contradict these beliefs. © Society for Adolescent Medicine, 2004 From the Department of Pediatrics, University of Kansas School of Medicine-Wichita, Wichita, Kansas (S.E.S., R.R.W.), Wesley Clinics, Wichita, Kansas (S.E.S., R.R.W.), and Sedgwick County Health Department, Wichita, Kansas (S.E.S., R.R.W., R.H.O.). Address correspondence to: Dr. Stephen Smalley, 2503 Timber Crest Lane, Highland Village, TX 75077. E-mail: [email protected] Manuscript accepted January 16, 2004. 1054-139X/04/$–see front matter doi:10.1016/j.jadohealth.2004.01.005
KEY WORDS:
Heart disease Attitudes Beliefs Habits Lifestyle Smoking Obesity Adolescents
Although there is a large body of evidence regarding the effectiveness of lifestyle and dietary modification in preventing cardiovascular heart disease (CHD), obesity and smoking continue to be major problems in adolescence. Although the prevalence of smoking in high school has declined since 1997, the National Youth Tobacco Survey (NYTS) showed tobacco usage to be approximately 15% in middle school and 34% in high school [1]. NYTS also found that 80% of smokers began the habit before 18 years of age. Obesity, conversely, is on the rise with the prevalence of adolescents above the 95th percentile in body mass index (BMI) doubling over the past 20 years [2]. Aside from dietary choices, sedentary lifestyles [3], such as television viewing [4], contribute to obesity, owing to reduced energy expenditure and a propensity for increased dietary intake of high calorie snacks. Individual attitudes and beliefs regarding cardiovascular disease risk factors have been studied in the past. Silagy et al found that 45% of obese adults recognized their dietary habits to be harmful, and 75% of smokers recognized their smoking to be harmful [5]. In those individuals, nearly all of them wanted to improve, but only half of them made an © Society for Adolescent Medicine, 2004 Published by Elsevier Inc., 360 Park Avenue South, New York, NY 10010
November 2004
ADOLESCENT HEART DISEASE ATTITUDES AND HABITS
attempt to do so. Avis et al showed similar results in which adult participants were asked open-ended questions to identify behaviors that would make heart disease or stroke less likely [6]. The results showed that there was high knowledge of risk factors, but when asked about personal habits, knowledge was not associated with lower risk behaviors. Frost surveyed risk factor knowledge in college students and found that almost all of them were able to identify hypertension, smoking, high cholesterol, and low exercise as risk factors [7], however, 16% reported that they smoked cigarettes, 33.5% of them exercised regularly, and 32.9% of them had their cholesterol levels checked. Behera et al assessed attitudes of low-income African-American women [8]. Those surveyed had a low awareness of the prevalence of cardiovascular disease, and they identified stress as being the most important risk factor. They further identified the media as an important source for health information as well as misinformation. Data from the 1990 U.S. Bureau of the Census showed that teenagers in neighborhoods with low income, education, and house values with high levels of poverty had poorer dietary habits and less physical activity than those living in higher socioeconomic status (SES) neighborhoods [9]. We assessed the attitudes and health habits regarding cardiovascular heart disease risk factors, as well as whether or not an adolescent’s attitude about cardiovascular disease had any relationship to their health habits. Secondary goals of the study included the relationship of BMI to habits and beliefs, as well as to family history of heart attack.
Methods The participants were youths aged 13 to 18 years who visited one of the clinic sites for routine or acute health care in Wichita, Kansas from June 2002 to February 2003. The sites included the University of Kansas pediatric resident continuity clinic and the Teen Health Station of the Sedgwick County Health Department. The reimbursement to the continuity clinic consists of 75% Medicaid, 10% no insurance, and 15% private insurance. The Teen Health Station serves patients of whom 31% have Medicaid; 44%, no insurance; 17%, private insurance; 8%, unknown. Adolescents that agreed to participate in the study had weight and height measured, and then they completed the survey in a room separate from their parents. There were English and Spanish versions of the survey. The surveyor recorded height and
375
weight, and then left the room to allow the participant to complete the survey in privacy. The questionnaire asked for age, gender, and ethnicity. The next section included health habits: how many times a week did they participate in exercise that made them breathe hard and sweat for at least 20 minutes at a time, how many cigarettes had they smoked per day, and how many times per week had they eaten a meal from a fast food restaurant or a vending machine. Twenty-minute sustained exercise sessions reported on a per-week basis is considered by some to be a minimally acceptable duration for exercise [10 –12]; others accept 30 minutes as standard [13]. Exercise bouts that induce sweating have been found to provide a simplified way of reporting exercise intensity with cardiovascular health benefits [14]. Smoking was reported on a daily basis for ease of estimation for the participants. A binomial variable was created stratifying participants into smoking and nonsmoking groups. Nielsen and Popkin report from the Continuing Survey of Food Intake for Individuals: 1977 to 1996 (CSFII) an increasing trend in portion size that may result from “value adding” [15]. The same body of data shows increased consumption of pizza, cheeseburgers, and french fries, in addition to sugared beverages [16]. Vending machines were included in this assessment because of their increased appearance on school campuses in the recent past and the high calorie, low nutrition, and high fat items that they sell [17,18]. Therefore, it was felt that fast food and vending machine food consumption would be a reasonable approximation of high calorie, high fat food consumption, while keeping the survey brief. The next section asked the participant to rate their attitudes about cardiovascular heart disease risk factors on a 5-point Likert scale, ranging from “strongly disagree” to “strongly agree.” This section contained three statements: being overweight may cause heart disease, smoking cigarettes may cause heart disease, and eating a high fat diet may cause heart disease. The American Heart Association has identified these as modifiable risk factors for the development of cardiovascular heart disease [19]. The final section asked the participant whether or not they had knowledge that a parent, guardian, or grandparent sustained a heart attack. Whether or not a parent accompanied the participant to the clinic visit was also recorded on the survey, as it was felt to be a possible confounding variable. Descriptive statistics were derived for each of the survey variables. Binomial variables were created for categorizing individuals with a BMI ⬍ the 85th
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percentile vs. those with a BMI ⱖ the 85th percentile (overweight or obese) [20], as well as for whether or not a parent, guardian, or grandparent had a history of heart attack. Ages were combined into the following groups: 13- and 14-year-olds, 15- and 16-yearolds, and 17- and 18-year-olds. Responses to the habit and attitude questions were stratified by age group. Correlations between the attitude and habit responses were assessed by Spearman’s rank correlation test because the attitude responses were felt to be ordinal variables rather than continuous variables. Contingency table analysis was used for univariate categorical variable significance testing. Logistic regression modeling was developed for multivariate modeling of binomial variables (i.e., overweight or obese vs. nonobese and smokers vs. nonsmokers) to obtain odds ratios (OR). Model building was based on the principles developed by Hosmer and Lemeshow [21]. Statistical significance was defined as a p value ⱕ .05. The Institutional Review Board at Wesley Medical Center in Wichita and the University of Kansas School of MedicineWichita approved the survey. A formal collaborative agreement was made with the Sedgwick County Health Department Teen Health Station.
Results The demographics of the participants are listed in Table 1. The percentage of participants with BMI ⱖ the 85th and 95th percentiles (Table 2) is larger than those reported in the National Health and Nutritional Examination Surveys III, which was 21.7% and 12.8% for those at or above the 85th and 95th percentiles for boys, and 21.2% and 8.8% in girls, respectively [2]. The habit and attitude assessment is found in Table 3. Fast food and vending machine food consumption increased with age (p ⬍ .001), but there was not a statistically significant relationship between the reporting of exercise amount per week and age. Frequency distribution of exercise amount shows close to half of the population reporting three sustained exercise sessions per week or less (Figure 1). Frequency of smoking increased with age (Figure 2). The percentage of smokers in this survey was comparable with national averages [1]. Three-fourths of the 17- and 18-year-olds agreed with all three risk factors, and “strongly agree” was the most common attitude response (Figure 3). Participant attitudes were disparate to their reported habits.
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Table 1. Characteristics of Population (N ⫽ 348) Characteristic
Percent of Total
Age Mean (years) 13- and 14-year-olds 15- and 16-year-olds 17- and 18-year-olds Gender Male Female Race White Black Hispanic Asian Other BMI (kg/m2) Males Females 13- and 14-year-olds 15- and 16-year-olds 17- and 18-year-olds Site KU Continuity Clinic Teenage Health Station Parents present at visit Yes No Known relative that sustained heart attack No or don’t know Grandparent Parent/guardian Both parent/guardian and grandparent Language of Survey English Spanish
15.3 112 (32) 147 (42) 89 (26) 141 (41) 207 (59) 115 (33) 118 (34) 98 (28) 3 (1) 14 (4) 24.2 24.4 23.6 24.5 25.0
SD SD SD SD SD
⫾ ⫾ ⫾ ⫾ ⫾
5.2 6.2 5.8 6.0 5.9
53 (15) 295 (85) 175 (50) 173 (50) 225 (65) 101 (29) 12 (3) 10 (3) 329 (95) 19 (5)
Adjusted odds ratios derived from a multivariate logistic regression model with an outcome variable of being overweight or obese showed gender and
Table 2. Percentages of Population at or Above the 85th and 95th Percentiles for Age-appropriate Body Mass Index (BMI)
13- and 14-year-olds Male Female 15- and 16-year-olds Male Female 17- and 18-year-olds Male Female
Greater than or equal to the 85th percentile for BMI (%)
Greater than or equal to the 95th percentile for BMI (%)
34 51 39 38 45 35 40 52 35
25 24 26 23 25 22 19 28 15
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Table 3. Report of Attitude and Habits Attitudes 1 ⫽ SD; 2 ⫽ D; 3 ⫽ DN; 4 ⫽ A; 5 ⫽ SA Attitude Overweight 13- and 14-year-olds 15- and 16-year-olds 17- and 18-year-olds Smoking 13- and 14-year-olds 15- and 16-year-olds 17- and 18-year-olds High fat diet 13- and 14-year-olds 15- and 16-year-olds 17- and 18-year-olds a
Habits
Mode
Agreea (%)
3 4 5
48 68 76
5 5 5
73 80 76
3 3 5
46 59 74
Habit Exercise per week 13- and 14-year-olds 15- and 16-year-olds 17- and 18-year-olds Smoking per day 13- and 14-year-olds 15- and 16-year-olds 17- and 18-year-olds Fast food per week 13- and 14-year-olds 15- and 16-year-olds 17- and 18-year-olds
Mean (S.D.) 3.3 (⫾ 2.3) 2.8 (⫾ 2.6) 3.1 (⫾ 3.0) 0.1 (⫾ 1.0) 1.0 (⫾ 2.9) 3.4 (⫾ 6.2) 2.0 (⫾ 2.0) 2.5 (⫾ 2.1) 3.5 (⫾ 3.4)
SD ⫽ Strongly Disagree, D ⫽ Somewhat Disagree, DN ⫽ Don’t Know, A ⫽ Somewhat Agree, and SA ⫽ Strongly Agree. Percentage of those that either somewhat agree or strongly agree.
smoking to be statistically significant. The OR for males compared with females being obese or overweight was 1.66 (95% CI 1.1–2.6, p ⫽ .03) and the OR for smokers compared with nonsmokers was 1.90 (95% CI 1.0 –3.4, p ⫽ .05). Multivariate logistic regression modeling also showed age (p ⬍ .001) and a history of a parent, guardian, or grandparent having a heart attack (p ⫽ .001) to be significantly related to an outcome variable of smoking vs. nonsmoking. With age included as a covariate, the odds of being a smoker were 2.7 times greater (OR 95% CI 1.5– 4.9) for those individuals surveyed who reported a parent/guardian or grandparent having a heart attack.
Limitations
tutes an average amount of fast food per week. Even when vending machine food is included in the question, it still does not account for high fat, high salt, low fiber foods obtained as a la carte choices in school cafeterias or at home. A better question may have focused on the hours of television and computer usage per week, of which national averages have been reported [22]. The wording of the smoking habit question may have yielded results that were falsely low. Instead of reporting smoking behavior on a daily basis, the question could have asked about smoking on a weekly basis.
Discussion
The “fast food” question was a weakness of the survey. There is no reference value for what consti-
The hope from a public health perspective would be that all participants agree with the three statements regarding cardiovascular heart disease, and the ma-
Figure 1. Report of exercise and fast food intake. Participants were asked to report how many times they exercised per week. An exercise session was considered an activity of at least 20 minutes in which the participant breathed hard and sweated. Fast food intake also included meals from a vending machine. Intake was also reported for a per week basis.
Figure 2. Report of smoking by age group.
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Figure 3. Attitude assessment of cardiovascular heart disease risk (CHD) risk factors by age groups.
jority usually did, especially in the older age groups. All age groups in the survey agreed that smoking was an important cause of cardiovascular heart disease, however only the older-aged participants were able to identify obesity and high fat diet as contributors. This suggests that younger adolescents are already aware of the hazards of smoking, whereas the cardiovascular impact of obesity and poor diet aren’t learned until they are older. Participant habits were in contradiction to these beliefs. The most important inconsistency was between the attitudes and habits regarding cigarettes. One-third of 17- and 18-year-olds smoked, despite three-fourths of the group acknowledging its role in cardiovascular heart disease. This survey showed a greater frequency of overweight and obese individuals as compared with national averages. There are a number of possible reasons to account for this. The reference data come from the National Health and Nutrition Examination Survey (NHANES III), which is over 10 years old. The Bogalusa Heart Study was a longitudinal study from 1973 to 1994 that observed an increased weight of 5.7 kg in 15- to 17-year-olds in this time period, with most of the rise occurring over the last 10 years of the survey [23]. Preliminary analysis from the NHANES IV, which covers 1999 to 2000, also reflects this trend: 15% of 12- to 19-year-olds are at or above the 95th percentile for BMI, which reflects a 4% increase from NHANES III [24]. Another reason for the disparity could stem from the fact that the majority of participants in this survey came from families of lower socioeconomic status; however, relationships between socioeconomic status and obesity have been difficult to establish [25], particularly in males and in ethnicities other than white [26].
There was a statistically significant relationship between smoking and BMI. Participants who smoked were 1.9 times more likely to be overweight or obese. The data may have identified a subpopulation of adolescents that will enter adulthood with two modifiable risk factors for cardiovascular heart disease. When the participants reported a heart attack occurring in either a parent/guardian or grandparent, they were 2.7 times more likely to be smokers, even when age was controlled for in a multivariate model. The data suggest that having a relative with a heart attack is not a deterrent to smoking, but may actually prove to be a risk factor for smoking in adolescents. The reporting of a “heart attack” may be a surrogate marker for a family history of smoking. Other studies have suggested that parental smoking may influence adolescents to smoke [27,28]. Adolescents possess accurate knowledge of cardiovascular heart disease risk factors as reflected in their attitude assessments; however, these attitudes appear to have no relationship to their lifestyle choices. This observation has substantial implications for the health care professional. The adverse lifestyle choices made by adolescents cannot be attributed to lack of knowledge. Motivation to make positive changes in health habits is, therefore, the goal. This lack of patient motivation was perceived as the number one barrier by pediatricians against the successful treatment of overweight children [29]. However, one study found teenagers to be receptive to preventive counseling by a health care professional with regard to diet, exercise, smoking, and alcohol [30]; the impact on health habits from this 20-minute counseling session was small, but significant. A question that needs to be posed, then, is how
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much more significant a change could be made if the counseling was coming from the adolescent’s own physician? Prevention should be the main focus for health professionals. Habits learned in childhood and adolescence carry over into adulthood, where they will be more difficult to change. The knowledge of cardiovascular disease risk factors does not influence the health behaviors of adolescents, therefore, the challenge to the health care professional will be to both educate and motivate changes in health habits. We thank Katherine Melhorn, M.D., Brian DeBrot, M.D., and Phillip Allen, M.D., Ph.D. for help with development of the project, as well as Mary Jane Whitehair, A.R.N.P., Mark Harrison, M.D., Beverly Dean, Jill Burke, Virginia Parker, Denice Maness, Mary Ann Bauersfield, P.A.-C., Megan Langston, and Melissa Winter-Foss for their contributions.
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