- Email: [email protected]
Physiologic cardiovascular risk factors in a biracial cohort of adolescents
160
POSTER PRESENTATIONS
Purpose: Diabetes Mellitus Type 2 (DM2), is emerging as a major health concern for children and adolescents. Recent published reports show an increase in the prevalence of DM2 among adolescents attending diabetes clinics. The objectives of this study were to assess risk factors for, and to determine the prevalence of, DM2 among adolescents attending an outpatient adolescent medicine clinic. Methods: All adolescent patients who presented to the adolescent outpatient clinic were asked to participate in the study. The DM2 risk factor questionnaire included risk assessment such as: racial/ ethnic status, family history of DM, maternal gestational diabetes, birth weight ⱖ9 lbs, obesity or body mass index (BMI) ⱖ85th percentile, acanthosis nigricans, and polycystic ovarian syndrome. Patients identified with one or more risk factors were offered on-site same day testing of either a Casual (non-fasting) Plasma Glucose (CPG) or Fasting Plasma Glucose (FPG) blood test (depending on their most recent meal), and an insulin level. If the fasting glucose sample was ⱖ110 and ⬍126 mg/dl, the patients were offered a 2-hour Oral Glucose Tolerance Test (OGTT). Criteria for diagnosis of DM2 and impaired glucose tolerance were in accordance with the recommendations established by the American Diabetes Association Expert Committee. Chi square analysis and Pearson correlation coefficients were the major methods of statistical analysis. Results: 113 patients completed the DM2 risk factor questionnaire (75% female; mean age 15.8 ⫾ 1.7 years; 34.0% African American, 29% Caucasian, 13% Puerto Rican, 17% other). The majority of the patients (92%) had at least one risk factor to make them eligible for the blood testing. 99% of this group completed testing. The mean BMI was 25.0 ⫾; 6.4 with 48.5% ⱖ the 85th centile, and 17% ⱖ the 99th centile. 103 blood samples were taken (36 fasting, 67 nonfasting), and were analyzed for glucose levels (N ⫽ 103) and for insulin levels (N ⫽ 96). The mean glucose values were similar in the fasting versus non-fasting group (85.0 mg/dl, 84.3 mg/dl respectively). The mean for the fasting insulin values was 22.1 uIU/mL with a range of 6.14 to 54.43 uIU/mL and the mean for the non-fasting insulin values was 39.6 uIU/mL with a range of 8.52 to 240.67 uIU/mL. No patients were diagnosed with Diabetes Mellitus Type 2. Seven (19.4%) of the fasting individuals had high insulin levels suggestive of insulin resistance. The fasting glucose to fasting insulin ratio was significantly lower in the obese (BMI ⱖ 85th centile) individuals than in the non-obese individuals (3.71 ⫾ 1.86, 6.10 ⫾ 2.60, p ⱕ .005). BMI was significantly correlated with fasting insulin levels (p ⬍ .003) and total sites of acanthosis nigricans (p ⬍ .001). Conclusions: On-site same day testing for DM2 in a high risk adolescent outpatient population optimized screening compliance. While no cases of DM2 were identified in this small sample, future study of the prevalence of DM2 is warranted given the high number of risk factors and high prevalence of obesity seen in this adolescent outpatient population. PATTERNS OF PRE-ADMISSION PHYSICAL ACTIVITY AMONG MALE JUVENILE DETAINEES Sergio R. R. Buzzini, M.D., Melanie A. Gold, D.O., Teresa N. D. Buzzini, Psy.D., Julie Downs, Ph.D., and Pamela J. Murray, M.D., M.H.P. Division of Adolescent Medicine, Children’s Hospital of Pittsburgh, Pittsburgh, PA; Mercy Behavioral Health, Pittsburgh, PA; Carnegie Mellon University, Pittsburgh, PA. Purpose: Healthy People 2010 recommends that youth do sufficient vigorous physical activity (at least 20 minutes per day, 3
JOURNAL OF ADOLESCENT HEALTH Vol. 32, No. 2
times per week), or sufficient moderate physical activity (at least 30 minutes per day, 5 days per week). Nearly 700,000 youth are admitted annually to juvenile correctional facilities in the United States, but little is known about their physical activity patterns. This study explores the pre-admission levels of sufficient vigorous and moderate physical activity, strengthening exercises, team sport participation, and body mass index (BMI) of male juvenile detainees and compares them to male data from the 2001 National Youth Risk Behavior Survey (YRBS). Methods: As part of a larger study, we surveyed 305 male adolescents, ages 12-20 years (mean 15.8 ⫾ 1.5), from a juvenile detention facility. We limited the analysis to blacks (74%) and whites (20%), excluding other racial groups (6%). A 50-minute, anonymous survey was verbally administered to small groups of 2 to 5 youth. Our survey included items based on six YRBS variables measuring past week sufficient vigorous and moderate physical activity, lack of any physical activity, and strengthening exercises; past year participation in team sports, and BMI. We conducted Chi-square analyses to compare racial differences for all six variables within the detainee sample. We conducted tests for significance of each proportion to compare the detainee sample with the male 2001 YRBS sample. Because multiple tests were conducted, a conservative alpha level of ␣ ⫽ .01 using two-tailed tests was chosen. Results: Detained white males were more likely to report sufficient moderate physical activity than detained black males (52% vs. 23%, ⫽ 18.38, p ⬍ .001). Further, detained white males were less likely to report team sports participation compared to detained black males (43% vs. 67%, ⫽ 11.25, p ⬍ .001). There were no significant racial differences in reported vigorous physical activity, lack of any physical activity, strengthening exercises, or BMI within the detained sample. When we compared the detained sample to the male YRBS sample, detained white males were more likely than YRBS white males to report participating in sufficient moderate physical activity (52% vs. 30%, z ⫽ 3.71, p ⬍ .001), and they were less likely to report team sports participation (43% vs. 62%, z ⫽ 2.93, p ⬍ .01), but there were no other significant differences in the remaining four variables. Detained black males reported marginally less sufficient vigorous physical activity than the black YRBS sample (66% vs. 72%, z ⫽ 1.99, p ⬍ .05), and were marginally more likely to report lack of any physical activity (12% vs. 8%, z ⫽ 2.12, p ⬍ .05), but there were no significant differences in the remaining four variables. Conclusion: The hypothesis that detained youth have overall poorer physical activity patterns than community-based youth is not supported by this data. Future analyses of the type, structure, and supervision of physical activity and team sports participation from this data set may identify the qualities of physical activities that are mediators of resilience for at-risk youth. PHYSIOLOGIC CARDIOVASCULAR RISK FACTORS IN A BIRACIAL COHORT OF ADOLESCENTS Elizabeth Goodman, M.D., Stephen R. Daniels, M.D., Ph.D., John A. Morrison, Ph.D., and Lawrence M. Dolan, M.D. Schneider Inst. for Health Policy, Heller Sch. for Social Policy and Management, Brandeis Univ., Waltham, MA, and Divisions of Cardiology and Endocrinology, Children’s Hosp. Med Ctr., Cincinnati, OH. Purpose: Cardiovascular (CV) disease is the leading cause of mortality in the United States. The atherogenic process is known to begin early in life and research suggests secular trends towards increasing CV risk factors, especially increasing body mass index
February 2003
POSTER PRESENTATIONS
(BMI), among the young. However, little recent community-based research has been done to describe CV risks in the young, especially for physiologic as opposed to behavioral risks. Objective: To describe physiologic CV risk factors and their correlations in a community-based sample of junior and senior high school students and determine if sociodemographic differences exist in the prevalence of these risks. Methods: Cross sectional study of 1668/2652 (62.9%) non-Hispanic black and white adolescents from the single public junior and high schools of an urban school district near a large Midwestern city. From among those eligible for inclusion, more females than males participated (66.9% vs 59.4%, p ⬍ .001). There were no differences in race, age, or school type in study participation. 49.8% of participants were male, 50.5% black. Mean age was 15.3 ⫾ 1.6 years. 90.2% (N ⫽ 1508) had a fasting morning blood sample drawn for measurement of 6 known CV risk factors: total cholesterol (TC), LDL cholesterol (LDL-C), HDL cholesterol (HDLC), triglycerides (TG), fibrinogen, and glycosylated hemoglobin (HgbA1c). Height and weight were measured on 97.8% (N ⫽ 1631). Overweight was defined as a BMI ⬎85% and obesity as BMI ⱖ 95% based on the 2000 CDC Growth Chart standards. Results: Mean values (SD) for measured CV risks are presented below. Kruskal-Wallis ANOVA revealed significant (p ⱕ .001) race x sex group differences in prevalence for all 6 risk factors. Risk factors were significantly correlated with each other. BMI showed the strongest correlations among risk factors, and was most strongly correlated with fibrinogen (r ⫽ ⫺.33, p ⬍ .001) and HDL-C (r ⫽ ⫺0.32, p ⬍ .001). BMI was not correlated with HgbA1c, the most weakly correlated risk factor. Based on National Cholesterol Education Program Guidelines, 36.6% had at least one lipid-related CV risk, of whom 48.5% had a low HDL-C. 38.6% were overweight and 20.5% were obese.
Males Total TC (mg/dl) LDL-C (mg/dl) HDL-C (mg/dl) TG (mg/dl) HgbAlc (%) Fibrinogen (mg/dl) BMI
White
Females Black
White
Black
148.9 (27.8) 143.6 (28.5) 147.8 (26.2) 150.6 (27.0) 153.9 (28.4) 87.9 (24.4)
85.0 (24.4)
87.3 (23.4)
87.7 (23.9)
91.9 (25.3)
45.6 (11.1)
41.3 (9.5)
46.9 (11.9)
46.0 (9.9)
48.6 (11.6)
76.8 (41.7)
87.9 (57.9)
67.7 (29.3)
84.6 (38.9)
66.3 (29.0)
5.0 (0.6)
5.0 (0.4)
5.1 (0.5)
4.9 (0.4)
5.0 (0.5)
283.7 (58.4) 271.4 (54.9) 271.3 (50.3) 286.0 (54.2) 306.9 (64.0) 24.1 (6.0)
23.4 (5.4)
24.4 (6.2)
23.4 (5.4)
25.6 (7.0)
Conclusions: Physiologic risks for which presage development of CV disease in later life are prevalent among youth. Overweight and obesity are the most common risks, followed by low levels of HDL-C. These risks are correlated, especially with BMI, suggesting that weight reduction may improve other clinically silent risks. CALCANEAL ULTRASOUND MEASUREMENTS AND PUBERTAL MATURATION IN GIRLS Albert Hergenroeder, M.D., Deanna Hoelscher, Ph.D., R.D., R. Sue Day, Ph.D., Steve Kelder, Ph.D., M.P.H., and Jerri Ward, M.A., R.D. University of Texas-Houston School of Public Health and Baylor College of Medicine, Houston, TX.
161
Purpose: The purpose of this study was to describe calcaneal ultrasound measurements in adolescent females as a function of pubertal and menstrual status and anthropometric measurements. Methods: This was a cross-sectional, descriptive study done at baseline of the IMPACT (Incorporating More Physical Activity and Calcium in Teens) study, a 2-year, school-based, health education intervention designed to increase bone mass by promoting the intake of calcium-containing foods and weight-bearing physical activity in middle school girls. Schools in central Texas were recruited using established networks. Inclusion criteria: a physical education (PE) teacher(s) to teach the IMPACT curriculum, equivalent amounts of scheduled PE classes for cohort students in the 6th grade for Year 1, an on-site cafeteria kitchen, no competing programs and no special status (i.e., not a designated magnet or special services school). Parental consent and student assent were obtained before participation. Student exclusion criteria: reporting a medical condition that prevented participation in PE, or that affected bone mineralization; or taking a medication that interfered with bone mineralization. 718 girls in the 6th grade from 12 middle schools with a mean age of 11.6 ⫾ 0.4 years were enrolled with a distribution of 72% nonHispanic white, 12% Hispanic, 5% African-American. Body weight, height and calf circumference were measured using standard techniques. Body mass index (BMI, kg/meters2) was calculated. Selfassessment of pubertal development was accomplished using standard drawings and recorded as 1 of 5 breast and pubic hair stages. Menarchal status (premenarchal or postmenarchal) was determined during an interview with subjects. A pubertal status variable was created based on pubertal self-assessment and consisted of 3 categories: prepubertal (breast and pubic hair ratings ⫽ 1; peripubertal (breast or pubic hair ratings ⫽ 2– 4; and pubertal (breast or pubertal rating ⫽ 5). Quantitative ultrasound (QUS) measurements as a measure of bone mass were done using a Lunar Achilles⫹ ultrasound densitometer. Valid QUS measurements were obtained on 662 subjects. The outcome measures were the 2 variables measured by QUS: broadband ultrasound attenuation (BUA, dB/MHz); and speed of sound (SOS, m/s); and, the Stiffness Index (SI), calculated from BUA and SOS. Results: 5% of subjects were prepubertal, 89% peripubertal, and 4% pubertal. 80% were premenarchal. Mean (⫾ S.D.) values were: BMI ⫽ 19.5 ⫾ 3.9 kg/m2; BUA ⫽ 95.5 ⫾ 14.9 dB/MHz; SOS ⫽ 1536 ⫾ 28m/s, and SI ⫽ 73.8 A ⫾ 14.9. Calf circumference and BMI correlated (p ⬍ .01) with BUA (r ⫽ 0.46, 0.42, respectively), SOS (r ⫽ 0.27, 0.22), and SI (r ⫽ 0.45, 0.40). BUA, SOS and SI (p ⬍ .01) were related to self-assessed pubic hair (rho ⫽ 0.22, 0.22, and 0.25, respectively) and self-assessed breast development (rho ⫽ 0.21, 0.22, and 0.23, respectively). Menarchal status predicted BUA, SOS and SI (p ⬍ .01 in all three) while adjusting for BMI. Conclusion: QUS measurements correlated with estimates of pubertal maturation and anthropometric measurements, as expected. The higher correlation between calf skinfold and QUS measurements, compared to BMI, suggests that increased size of the lower leg, due to increased fat-free or fat mass, may have a greater impact on calcaneal bone mass than body weight. Menarchal status predicted QUS measurements, controlling for BMI. These results reinforce the use of QUS measures of bone mass in research involving large groups of adolescents. PREVALENCE OF AND RISK FACTORS ASSOCIATED WITH DISORDERED EATING AMONG UNIVERSITY UNDERGRADUATES Betty Staples, M.D. and Terrill Bravender, M.D., M.P.H. Dept. of Pediatrics, Duke University Medical Center, Durham, NC.
POSTER PRESENTATIONS
Purpose: Diabetes Mellitus Type 2 (DM2), is emerging as a major health concern for children and adolescents. Recent published reports show an increase in the prevalence of DM2 among adolescents attending diabetes clinics. The objectives of this study were to assess risk factors for, and to determine the prevalence of, DM2 among adolescents attending an outpatient adolescent medicine clinic. Methods: All adolescent patients who presented to the adolescent outpatient clinic were asked to participate in the study. The DM2 risk factor questionnaire included risk assessment such as: racial/ ethnic status, family history of DM, maternal gestational diabetes, birth weight ⱖ9 lbs, obesity or body mass index (BMI) ⱖ85th percentile, acanthosis nigricans, and polycystic ovarian syndrome. Patients identified with one or more risk factors were offered on-site same day testing of either a Casual (non-fasting) Plasma Glucose (CPG) or Fasting Plasma Glucose (FPG) blood test (depending on their most recent meal), and an insulin level. If the fasting glucose sample was ⱖ110 and ⬍126 mg/dl, the patients were offered a 2-hour Oral Glucose Tolerance Test (OGTT). Criteria for diagnosis of DM2 and impaired glucose tolerance were in accordance with the recommendations established by the American Diabetes Association Expert Committee. Chi square analysis and Pearson correlation coefficients were the major methods of statistical analysis. Results: 113 patients completed the DM2 risk factor questionnaire (75% female; mean age 15.8 ⫾ 1.7 years; 34.0% African American, 29% Caucasian, 13% Puerto Rican, 17% other). The majority of the patients (92%) had at least one risk factor to make them eligible for the blood testing. 99% of this group completed testing. The mean BMI was 25.0 ⫾; 6.4 with 48.5% ⱖ the 85th centile, and 17% ⱖ the 99th centile. 103 blood samples were taken (36 fasting, 67 nonfasting), and were analyzed for glucose levels (N ⫽ 103) and for insulin levels (N ⫽ 96). The mean glucose values were similar in the fasting versus non-fasting group (85.0 mg/dl, 84.3 mg/dl respectively). The mean for the fasting insulin values was 22.1 uIU/mL with a range of 6.14 to 54.43 uIU/mL and the mean for the non-fasting insulin values was 39.6 uIU/mL with a range of 8.52 to 240.67 uIU/mL. No patients were diagnosed with Diabetes Mellitus Type 2. Seven (19.4%) of the fasting individuals had high insulin levels suggestive of insulin resistance. The fasting glucose to fasting insulin ratio was significantly lower in the obese (BMI ⱖ 85th centile) individuals than in the non-obese individuals (3.71 ⫾ 1.86, 6.10 ⫾ 2.60, p ⱕ .005). BMI was significantly correlated with fasting insulin levels (p ⬍ .003) and total sites of acanthosis nigricans (p ⬍ .001). Conclusions: On-site same day testing for DM2 in a high risk adolescent outpatient population optimized screening compliance. While no cases of DM2 were identified in this small sample, future study of the prevalence of DM2 is warranted given the high number of risk factors and high prevalence of obesity seen in this adolescent outpatient population. PATTERNS OF PRE-ADMISSION PHYSICAL ACTIVITY AMONG MALE JUVENILE DETAINEES Sergio R. R. Buzzini, M.D., Melanie A. Gold, D.O., Teresa N. D. Buzzini, Psy.D., Julie Downs, Ph.D., and Pamela J. Murray, M.D., M.H.P. Division of Adolescent Medicine, Children’s Hospital of Pittsburgh, Pittsburgh, PA; Mercy Behavioral Health, Pittsburgh, PA; Carnegie Mellon University, Pittsburgh, PA. Purpose: Healthy People 2010 recommends that youth do sufficient vigorous physical activity (at least 20 minutes per day, 3
JOURNAL OF ADOLESCENT HEALTH Vol. 32, No. 2
times per week), or sufficient moderate physical activity (at least 30 minutes per day, 5 days per week). Nearly 700,000 youth are admitted annually to juvenile correctional facilities in the United States, but little is known about their physical activity patterns. This study explores the pre-admission levels of sufficient vigorous and moderate physical activity, strengthening exercises, team sport participation, and body mass index (BMI) of male juvenile detainees and compares them to male data from the 2001 National Youth Risk Behavior Survey (YRBS). Methods: As part of a larger study, we surveyed 305 male adolescents, ages 12-20 years (mean 15.8 ⫾ 1.5), from a juvenile detention facility. We limited the analysis to blacks (74%) and whites (20%), excluding other racial groups (6%). A 50-minute, anonymous survey was verbally administered to small groups of 2 to 5 youth. Our survey included items based on six YRBS variables measuring past week sufficient vigorous and moderate physical activity, lack of any physical activity, and strengthening exercises; past year participation in team sports, and BMI. We conducted Chi-square analyses to compare racial differences for all six variables within the detainee sample. We conducted tests for significance of each proportion to compare the detainee sample with the male 2001 YRBS sample. Because multiple tests were conducted, a conservative alpha level of ␣ ⫽ .01 using two-tailed tests was chosen. Results: Detained white males were more likely to report sufficient moderate physical activity than detained black males (52% vs. 23%, ⫽ 18.38, p ⬍ .001). Further, detained white males were less likely to report team sports participation compared to detained black males (43% vs. 67%, ⫽ 11.25, p ⬍ .001). There were no significant racial differences in reported vigorous physical activity, lack of any physical activity, strengthening exercises, or BMI within the detained sample. When we compared the detained sample to the male YRBS sample, detained white males were more likely than YRBS white males to report participating in sufficient moderate physical activity (52% vs. 30%, z ⫽ 3.71, p ⬍ .001), and they were less likely to report team sports participation (43% vs. 62%, z ⫽ 2.93, p ⬍ .01), but there were no other significant differences in the remaining four variables. Detained black males reported marginally less sufficient vigorous physical activity than the black YRBS sample (66% vs. 72%, z ⫽ 1.99, p ⬍ .05), and were marginally more likely to report lack of any physical activity (12% vs. 8%, z ⫽ 2.12, p ⬍ .05), but there were no significant differences in the remaining four variables. Conclusion: The hypothesis that detained youth have overall poorer physical activity patterns than community-based youth is not supported by this data. Future analyses of the type, structure, and supervision of physical activity and team sports participation from this data set may identify the qualities of physical activities that are mediators of resilience for at-risk youth. PHYSIOLOGIC CARDIOVASCULAR RISK FACTORS IN A BIRACIAL COHORT OF ADOLESCENTS Elizabeth Goodman, M.D., Stephen R. Daniels, M.D., Ph.D., John A. Morrison, Ph.D., and Lawrence M. Dolan, M.D. Schneider Inst. for Health Policy, Heller Sch. for Social Policy and Management, Brandeis Univ., Waltham, MA, and Divisions of Cardiology and Endocrinology, Children’s Hosp. Med Ctr., Cincinnati, OH. Purpose: Cardiovascular (CV) disease is the leading cause of mortality in the United States. The atherogenic process is known to begin early in life and research suggests secular trends towards increasing CV risk factors, especially increasing body mass index
February 2003
POSTER PRESENTATIONS
(BMI), among the young. However, little recent community-based research has been done to describe CV risks in the young, especially for physiologic as opposed to behavioral risks. Objective: To describe physiologic CV risk factors and their correlations in a community-based sample of junior and senior high school students and determine if sociodemographic differences exist in the prevalence of these risks. Methods: Cross sectional study of 1668/2652 (62.9%) non-Hispanic black and white adolescents from the single public junior and high schools of an urban school district near a large Midwestern city. From among those eligible for inclusion, more females than males participated (66.9% vs 59.4%, p ⬍ .001). There were no differences in race, age, or school type in study participation. 49.8% of participants were male, 50.5% black. Mean age was 15.3 ⫾ 1.6 years. 90.2% (N ⫽ 1508) had a fasting morning blood sample drawn for measurement of 6 known CV risk factors: total cholesterol (TC), LDL cholesterol (LDL-C), HDL cholesterol (HDLC), triglycerides (TG), fibrinogen, and glycosylated hemoglobin (HgbA1c). Height and weight were measured on 97.8% (N ⫽ 1631). Overweight was defined as a BMI ⬎85% and obesity as BMI ⱖ 95% based on the 2000 CDC Growth Chart standards. Results: Mean values (SD) for measured CV risks are presented below. Kruskal-Wallis ANOVA revealed significant (p ⱕ .001) race x sex group differences in prevalence for all 6 risk factors. Risk factors were significantly correlated with each other. BMI showed the strongest correlations among risk factors, and was most strongly correlated with fibrinogen (r ⫽ ⫺.33, p ⬍ .001) and HDL-C (r ⫽ ⫺0.32, p ⬍ .001). BMI was not correlated with HgbA1c, the most weakly correlated risk factor. Based on National Cholesterol Education Program Guidelines, 36.6% had at least one lipid-related CV risk, of whom 48.5% had a low HDL-C. 38.6% were overweight and 20.5% were obese.
Males Total TC (mg/dl) LDL-C (mg/dl) HDL-C (mg/dl) TG (mg/dl) HgbAlc (%) Fibrinogen (mg/dl) BMI
White
Females Black
White
Black
148.9 (27.8) 143.6 (28.5) 147.8 (26.2) 150.6 (27.0) 153.9 (28.4) 87.9 (24.4)
85.0 (24.4)
87.3 (23.4)
87.7 (23.9)
91.9 (25.3)
45.6 (11.1)
41.3 (9.5)
46.9 (11.9)
46.0 (9.9)
48.6 (11.6)
76.8 (41.7)
87.9 (57.9)
67.7 (29.3)
84.6 (38.9)
66.3 (29.0)
5.0 (0.6)
5.0 (0.4)
5.1 (0.5)
4.9 (0.4)
5.0 (0.5)
283.7 (58.4) 271.4 (54.9) 271.3 (50.3) 286.0 (54.2) 306.9 (64.0) 24.1 (6.0)
23.4 (5.4)
24.4 (6.2)
23.4 (5.4)
25.6 (7.0)
Conclusions: Physiologic risks for which presage development of CV disease in later life are prevalent among youth. Overweight and obesity are the most common risks, followed by low levels of HDL-C. These risks are correlated, especially with BMI, suggesting that weight reduction may improve other clinically silent risks. CALCANEAL ULTRASOUND MEASUREMENTS AND PUBERTAL MATURATION IN GIRLS Albert Hergenroeder, M.D., Deanna Hoelscher, Ph.D., R.D., R. Sue Day, Ph.D., Steve Kelder, Ph.D., M.P.H., and Jerri Ward, M.A., R.D. University of Texas-Houston School of Public Health and Baylor College of Medicine, Houston, TX.
161
Purpose: The purpose of this study was to describe calcaneal ultrasound measurements in adolescent females as a function of pubertal and menstrual status and anthropometric measurements. Methods: This was a cross-sectional, descriptive study done at baseline of the IMPACT (Incorporating More Physical Activity and Calcium in Teens) study, a 2-year, school-based, health education intervention designed to increase bone mass by promoting the intake of calcium-containing foods and weight-bearing physical activity in middle school girls. Schools in central Texas were recruited using established networks. Inclusion criteria: a physical education (PE) teacher(s) to teach the IMPACT curriculum, equivalent amounts of scheduled PE classes for cohort students in the 6th grade for Year 1, an on-site cafeteria kitchen, no competing programs and no special status (i.e., not a designated magnet or special services school). Parental consent and student assent were obtained before participation. Student exclusion criteria: reporting a medical condition that prevented participation in PE, or that affected bone mineralization; or taking a medication that interfered with bone mineralization. 718 girls in the 6th grade from 12 middle schools with a mean age of 11.6 ⫾ 0.4 years were enrolled with a distribution of 72% nonHispanic white, 12% Hispanic, 5% African-American. Body weight, height and calf circumference were measured using standard techniques. Body mass index (BMI, kg/meters2) was calculated. Selfassessment of pubertal development was accomplished using standard drawings and recorded as 1 of 5 breast and pubic hair stages. Menarchal status (premenarchal or postmenarchal) was determined during an interview with subjects. A pubertal status variable was created based on pubertal self-assessment and consisted of 3 categories: prepubertal (breast and pubic hair ratings ⫽ 1; peripubertal (breast or pubic hair ratings ⫽ 2– 4; and pubertal (breast or pubertal rating ⫽ 5). Quantitative ultrasound (QUS) measurements as a measure of bone mass were done using a Lunar Achilles⫹ ultrasound densitometer. Valid QUS measurements were obtained on 662 subjects. The outcome measures were the 2 variables measured by QUS: broadband ultrasound attenuation (BUA, dB/MHz); and speed of sound (SOS, m/s); and, the Stiffness Index (SI), calculated from BUA and SOS. Results: 5% of subjects were prepubertal, 89% peripubertal, and 4% pubertal. 80% were premenarchal. Mean (⫾ S.D.) values were: BMI ⫽ 19.5 ⫾ 3.9 kg/m2; BUA ⫽ 95.5 ⫾ 14.9 dB/MHz; SOS ⫽ 1536 ⫾ 28m/s, and SI ⫽ 73.8 A ⫾ 14.9. Calf circumference and BMI correlated (p ⬍ .01) with BUA (r ⫽ 0.46, 0.42, respectively), SOS (r ⫽ 0.27, 0.22), and SI (r ⫽ 0.45, 0.40). BUA, SOS and SI (p ⬍ .01) were related to self-assessed pubic hair (rho ⫽ 0.22, 0.22, and 0.25, respectively) and self-assessed breast development (rho ⫽ 0.21, 0.22, and 0.23, respectively). Menarchal status predicted BUA, SOS and SI (p ⬍ .01 in all three) while adjusting for BMI. Conclusion: QUS measurements correlated with estimates of pubertal maturation and anthropometric measurements, as expected. The higher correlation between calf skinfold and QUS measurements, compared to BMI, suggests that increased size of the lower leg, due to increased fat-free or fat mass, may have a greater impact on calcaneal bone mass than body weight. Menarchal status predicted QUS measurements, controlling for BMI. These results reinforce the use of QUS measures of bone mass in research involving large groups of adolescents. PREVALENCE OF AND RISK FACTORS ASSOCIATED WITH DISORDERED EATING AMONG UNIVERSITY UNDERGRADUATES Betty Staples, M.D. and Terrill Bravender, M.D., M.P.H. Dept. of Pediatrics, Duke University Medical Center, Durham, NC.