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Clinical Pediatrics
http://cpj.sagepub.com/content/49/9/876
The online version of this article can be found at:
DOI: 10.1177/0009922810368135
2010 49: 876 originally published online 3 June 2010CLIN PEDIATR
Ruben Rodriguez, Jana Mowrer, Jessica Romo, April Aleman, Simón E. Weffer and Rudy M. Ortiz
Rural US Population
Ethnic and Gender Disparities in Adolescent Obesity and Elevated Systolic Blood Pressure in a
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Clinical Pediatrics
49(9) 876 –884
© The Author(s) 2010
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DOI: 10.1177/0009922810368135
http://clp.sagepub.com
Ethnic and Gender Disparities
in Adolescent Obesity and Elevated
Systolic Blood Pressure in a Rural
US Population
Ruben Rodriguez1, Jana Mowrer1, Jessica Romo, BA, BS1,
April Aleman, RN, CSN, MS2, Simón E. Weffer, PhD, MA, BA1,
and Rudy M. Ortiz, PhD, MS, BA1
Abstract
A cross-sectional study was conducted to assess the prevalence of overweight, obesity, and elevated systolic blood
pressure (SBP) in ethnically diverse adolescents (1064 males; 974 females; 13-17 years) in a rural community.
Prevalence of overweight was 20.4% in females and 17.5% in males. In contrast, the prevalence of obesity was 29.4%
in males and 14.5% in females. African American males had the highest prevalence of obesity (33.3%) compared
with non-Hispanic whites (26.3%). Prevalence of elevated SBP was higher than pre-elevated SBP in males regardless
of race/ethnicity, but not in females. Obese females had 4-fold and 9-fold greater odds of developing pre-elevated
SBP and elevated SBP, respectively, than their normal weight cohorts. Prevalence of obesity is almost twice that of
overweight in males in our rural population suggesting that adolescent males from disadvantaged, rural populations
are potentially at a greater risk for metabolic disorders than those in major metropolitan areas.
Keywords
abdominal obesity, adiposity, adolescents, body mass index, waist circumference
Introduction
The prevalence of overweight and obesity among US ado-
lescents has been increasing for the past 2 decades,1,2
although recent national data suggest that the prevalence of
overweight and obesity in adolescents may have plateaued.3
Nonetheless, most data on US children and adolescents
have come from studies on large metropolitan areas or
national surveys that do not distinguish between urban
and rural communities.1-7 Although African American
and Hispanic adolescents have higher incidence and
prevalence of overweight and obesity compared with
non-Hispanic whites adolescents,1,3-6 it is unknown
whether these ethnic differences exist in rural communi-
ties. Urban and rural differences have been shown with
respect to overweight and obesity in children, adoles-
cents, and adults,8-10 but these studies do not account for
ethnic/racial differences. Furthermore, prevalence data
from adolescents are scarce and not well characterized
with respect to ethnic/racial categorization.
The association between overweight and hypertension
in children has been reported in a variety of ethnic/racial
groups, with most studies finding higher blood pressure
and/or higher prevalence of hypertension in overweight
children.5,11-13 Body mass index (BMI) percentile was the
strongest determinant of elevated blood pressure when
examined in conjunction with gender, ethnicity, and
adiposity.5 However, a potential limitation of previous
studies may be the lack of data on the relationship
between waist circumference (WC) and elevated systolic
blood pressure (SBP) because abdominal obesity, using
WC, is an important predictor of metabolic complica-
tions. It has been linked to diabetes, dyslipidemia, insu-
lin resistance, hypertension, and metabolic syndrome in
the adult population.14-17 Abdominal obesity has also
been linked to an increase in cardiovascular (CV) and
metabolic risks in children and adolescents.15,18-22 This
study complements previous studies by extending
1University of California, Merced, CA, USA
2Merced Union High School District, Merced, CA, USA
Corresponding Author:
Rudy M. Ortiz, School of Natural Sciences, University of California,
Merced, 5200 N. Lake Road, Merced, CA 95343, USA
Email: rortiz@ucmerced.edu
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Rodriguez et al. 877
analysis to gain a better understanding of how BMI and
WC relate to SBP in adolescents from a predominantly
minority community.
Obesity and its associated comorbidities produce a
tremendous burden on public health systems. Under-
standing the potential health concerns in rural disadvan-
taged communities is critical for developing solutions
and improving public health in these areas. Therefore,
this study describes the current prevalence of over-
weight and obesity in adolescents using direct (not
self-reported) measurements in a rural, predominantly
minority population and uses these data to compare with
published values from urban populations. An additional
objective is to assess the relationships between BMI,
WC, and SBP in adolescents, accounting for differences
between gender and ethnicity. We address the hypothe-
sis that the prevalence of overweight and obesity in
minority adolescents in our rural population is greater
than that in similar groups from large metropolitan areas
or the national average.
Methods
Subjects
The study population consisted of 2038 (1064 males
and 974 females) ethnically diverse adolescents aged
between 13 and 17 years. The demographics of students
participating in the study are presented in Table 1. The
majority (79%) of the data were collected from Merced
Union High School District (MUHSD) annual health
assessments, with 21% from MUHSD annual sports
physicals for 2007. Students in MUHSD are predomi-
nately Hispanic/Latino (54%), followed by non-Hispanic
white (24%), Asian/Hmong (15%), African American
(5%), and other (2%). This study population is represen-
tative of Merced County, which has a population of pre-
dominately Hispanic/Latino residents (53%), followed
by non-Hispanic white (35%), Asian/Hmong (7%),
African American (4%), and other (1%).
Measurements
Age, gender, and ethnicity of participants were attained
from the annual health assessment and sports physicals.
Students self-reported race/ethnicity, which was cate-
gorized as non-Hispanic white, Hispanic/Latino, African
American, Asian/Hmong or other. For this article,
analyses focus only on comparisons between African
Americans, Hispanics, and non-Hispanic whites. Trained
technicians and nurses measured each participant’s
height, weight, WC, and SBP by using standardized pro-
tocols. Weight was measured to the nearest 0.1 kg using
a digital scale (Tanita HD-351, Tanita Corporation,
Arlington Heights, IL) and height was measured to the
nearest 0.1 cm using a measuring tape against a wall.
Waist circumference was measured to the nearest 0.1 cm
using a measuring tape, with the subject standing at
minimal respiration and the measurement taken in a
horizontal plane at the level of the high point of the iliac
crest as previously detailed.23 BMI was calculated using
the standard metric formula (kg/m2). SBP was measured
using an automated oscillometric device (Omron HEM-
780, Omron Healthcare, Bannockburn, IL). A mercury
sphygmomanometer and extra large cuff were used
when the cuff of the automated device was not large
enough to fit some of the subjects.
Anthropometric Definitions
Overweight and obesity were defined according to BMI
index cutoff points for age and gender published by the
Centers for Disease Control and Prevention.24 For the
purposes of this discussion, subjects were classified
using the following metrics: BMI <5th percentile =
“underweight,” BMI ≥5th and <85th percentile = “nor-
mal weight,” BMI ≥ 85th and ≤94.9th percentile = “over-
weight,” and BMI ≥95th percentile = “obese.”25 Only 53
(33 males, 20 females, 2.3%) of the 2038 adolescents
Table 1. Mean (±Standard Error) Values for Age, BMI, and
WC in Adolescents by Gender and Ethnicity
White, African
Non-Hispanic Hispanic American
n 613 1281 144
Males 312 671 81
Females 301 610 63
Age (years) 15 (0.1) 15 (0.1) 15 (0.1)
BMI (kg/m2)
Males 23.9 (0.32) 24.5 (0.21) 25.2 (0.72)
Normal 20.1 (0.14) 20.3 (0.10) 20.1 (0.29)
Overweight 25.0 (0.13) 24.8 (0.09) 24.8 (0.23)
Obese 31.5 (0.54) 31.5 (0.27) 32.6 (0.99)
Females 22.9 (0.32) 23.4 (0.22) 24.1 (0.68)
Normal 19.9 (0.15) 20.5 (0.09)a 20.3 (0.33)
Overweight 25.2 (0.15) 25.5 (0.10) 25.5 (0.36)
Obese 33.4 (0.86) 33.9 (0.61) 32.8 (0.86)
WC (cm)
Males 82.6 (0.84) 85.0 (0.64)a 84.9 (1.90)
Normal 77.8 (0.53) 78.5 (0.39) 77.4 (1.15)
WC ≥90th 108.5 (1.48) 107.7 (0.87) 108.5 (3.00)
Females 75.5 (0.85) 77.5 (0.58) 77.6 (1.86)
Normal 70.9 (0.52) 72.6 (0.32)a 72.2 (1.22)
WC ≥90th 101.5 (2.02) 101.1 (1.10) 102.5 (2.59)
Abbreviations: BMI, body mass index; WC, waist circumference.
aP < .05 versus White, non-Hispanics.
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878 Clinical Pediatrics 49(9)
were determined to be underweight and were removed
from the analyses and not considered here. There is no
agreed on definition of excess adiposity in children and
adolescents based on WC. For the purpose of this discus-
sion, we used the 90th percentile values of WC for gen-
der and age generated in NHANES (National Health and
Nutrition Examination Survey) III as cutoff values to
identify abdominal obesity.23 Blood pressure was classi-
fied using guidelines detailed in the “Fourth Report on
the Diagnosis, Evaluation, and Treatment of High Blood
Pressure in Children and Adolescents.”26 Because the
guidelines recommend multiple SBP measurements at
different times be used to diagnosis prehypertension and
hypertension, we used the terminology of Ostchega et al,27
which is similar to that of Din-Dzietham et al.28 Thus, a
SBP measurement in the prehypertensive range as defined
by SBP ≥90th percentile was termed “pre-elevated
SBP” and measurements in the hypertensive range, SBP
≥95th, was termed “elevated SBP.”26
Statistical Analysis
Means (±standard error) were compared by analysis of
variance (ANOVA) for ethnic/racial groups, gender, and
ethnic/racial group × gender differences. Prevalence rates
according to gender and ethnicity/race were compared
using c2 distribution statistics as previously described.29
Prevalence values are presented as percentage with
lower and upper 95% confidence intervals. Age had no
significant effect on any of the variables in the analyses
so data for each age category were combined. Relation-
ships between dependent and independent variables
were evaluated by simple regression, and correlations
were evaluated using Pearson correlation coefficients.
Means, regressions, and correlations were considered
significant at P < .05. Statistical analyses were per-
formed using Statview software (SAS, Cary, NC).
Categorical definitions of BMI, WC, and SBP were
also used in our analyses as they offer an alternative
approach to interpreting the data. In this study, we are pri-
marily interested in the differences across discrete cat-
egories (ie, “normal weight” vs “overweight” vs “obese”).
Because of our use of categorical variables, logistic
regression was used to calculate adjusted odds ratios.
When analyzing abdominal obesity using WC, a WC
≤90th percentile was used as the baseline outcome. For
the evaluation of SBP a SBP ≤90th percentile was used as
the baseline outcome and non-Hispanic white was the
comparison group for analyses using race and ethnicity.
After running a pooled model of both male and female
respondents, it was clear that there were both gender and
race/ethnicity effects. We then estimated models using
gender and race/ethnicity interaction terms, however,
what became clear was that gender was the most impor-
tant characteristic in the multivariate models, so a strat-
egy of running logistic regression with only males and
only females was employed. Adjusted odds ratio (95%
confidence intervals) and predicted probabilities were
estimated using logistic regression using STATA soft-
ware (version 10, StataCorp LP, College Station, TX).
Results
Body Mass Index
The population characteristics, along with mean BMI
and WC are shown in Table 1. The mean age for all
groups and genders was 15 ± 0.1 years (Table 1). The
overall prevalence of normal weight was 58.8% (57.9%
to 62.1%) with females (65.1%; 63.2% to 68.8%) higher
(P < .001) than males (53.1%; 51.2% to 58.6%). The
prevalence of normal weight in non-Hispanic white
(P < .05), Hispanic (P < .01), and African American (P <
.05) females was higher than in their male cohorts
(Figures 1A and 1B). Among males, Hispanics (P < .001)
and African Americans (P < .001) had lower prevalence
rates of normal weight than non-Hispanic whites (Figure
1A). Effects of ethnicity/race on the prevalence of nor-
mal weight in females were not detected (Figure 1B).
The overall prevalence of overweight was 18.9%
(17.4% to 20.6%) with females (20.4%; 17.7% to 22.4%)
higher (P < .05) than males (17.5%; 14.9% to 19.1%).
The prevalence of overweight in Hispanic (P < .01) and
African American (P < .05) females was higher than in
their male cohorts (Figure 1B). Effects of ethnicity/race
on the prevalence of overweight in males were not
detected. Among females, the prevalence of overweight
was higher (P < .01) in Hispanics than non-Hispanic
whites (Figure 1B).
The overall prevalence of obesity was 22.3% (19.3%
to 22.7%) with males (29.4%; 25.5% to 30.5%) twice
(P < .001) that of females (14.5%; 12.0% to 16.0%).
The prevalence of obesity was higher in all male ethnic/
racial groups than in their female cohorts (Figure 1B).
Among males, the prevalence of obesity was higher in
Hispanics (P < .001) and African Americans (P < .0001)
than in non-Hispanic whites (Figure 1A). The preva-
lence of obesity in males was nearly twice (P < .001)
that of overweight (Figure 1A). Among females, the
prevalence of obesity was lower in Hispanics (P < .001)
than in non-Hispanic whites.
Overall, the prevalence of overweight and obesity
combined was 41.2% (38.0% to 42.0%) with males
(46.9%; 43.2% to 48.8%) being higher (P < .001) than
females (34.9%; 31.2% to 36.8%). Among males, the
prevalence of overweight and obesity combined was
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Rodriguez et al. 879
greater (P < .001) in African Americans (51.8%; 41.1%
to 62.9%) and Hispanics (48.0%; 44.2% to 51.8%) than
non-Hispanic white males (43.3%; 37.5% to 48.5%).
Among females, the prevalence of overweight and obe-
sity combined was not different between non-Hispanic
whites (33.6%; 22.9% to 33.1%) and any of the other
groups (African Americans: 40.4%; 27.8% to 52.2%
and Hispanics: 34.8%; 33.2% to 40.8%).
The adjusted odds ratio data from logistic regres-
sions for BMI comparing normal weight and over-
weight by gender and ethnicity/race were not significant;
however, both Hispanic and African American males
and females exhibited a trend (28% to 45%) toward the
likelihood of being overweight (Table 2). The differ-
ences between the obese category and all other cate-
gories were large and significant, especially for males.
Normal-weight Hispanic and African American male’s
odds of being obese are increased by a factor of 2.11 and
2.50 (P < .001), respectively (Table 2). This finding can
also be interpreted using predicted probabilities where
Hispanic males are 37.6% more likely to be obese than
other males, and African Americans are 44.5% more
likely to be obese than other males (Table 3). Over-
weight Hispanic and African American male’s odds of
being obese increased by a factor of 1.88 (P < .001) and
1.96 (P < .05; Table 2), which when converted to pre-
dicted probabilities, result in Hispanics being 63.7%
more likely to be obese, and African Americans being
65.9% more likely to be obese (Table 3) than overweight
non-Hispanic white males. Although the trends toward
obesity where more pronounced for normal weight and
overweight African Americans they were not significant
at P < .05 (Table 2).
Waist Circumference
Independent of ethnicity/race, mean WC was 8.6%
greater (P < .001) in males than in females (Table 1).
The overall prevalence of normal weight as measured
by WC (<90th percentile) was 81.6% (81.4% to 84.7%)
with females (84.5%; 81.7% to 86.3%) greater (P <
.001) than males (80.5%; 78.6% to 83.4%). Among
males, the prevalence of normal weight measured by
WC was greater (P < .05) in non-Hispanic whites
(84.3%; 79.7% to 88.3%) than African Americans
(76.0%; 66.3% to 85.7%) and Hispanics (77.6%; 73.5%
to 80.5%). Among females, no effect of ethnicity/race
on normal weight was detected among the different
groups.
Conversely, the overall prevalence of abdominal
obesity as measured by WC (≥90th percentile) was
18.4% (15.4% to 18.7%) with males (19.5%; 16.6% to
21.4%) greater (P < .001) than females (15.5%; 13.7%
to 18.3%). Among males, abdominal obesity was higher
(P < .001) in African Americans (24.0%; 14.3% to
33.7%) and Hispanics (22.4%; 19.5% to 26.5%) than
non-Hispanic whites (15.7%; 11.7% to 20.3%). Among
females, abdominal obesity was higher (P < .0001) in
African Americans (18.0%; 8.4% to 27.6%) and His-
panics (16.9%; 13.8% to 20.3%) than in non-Hispanic
whites (14.7%; 10.7% to 19.3%).
Normal-weight Hispanic and African American
males’ odds of obesity are increased by a factor of 1.59
(P < .001) and 1.74 (P < .05), respectively, than normal-
weight non-Hispanic white males (Table 2). Converting
that finding to predicted probabilities, Hispanics males
were 23.1% more likely, and African American males
were 29.2% more likely of being obese (Table 2). Inde-
pendent of gender, Hispanics and African Americans
0
10
20
30
40
50
60
70
80
Prevalence (%)
Normal Wt
Overweight
Obese
A
cc
d,z
d,z
0
10
20
30
40
50
60
70
80
Whites Hispanics African-Americans
Prevalence (%)
B
‡‡
b
d,z
x
**
*
*
**
**
z
Figure 1. Prevalence (lower-upper 95% confidence
intervals) of normal (open bars), overweight (shaded bars),
and obese (striped bars) adolescents by ethnicity/race for
(A) males and (B) females
*Different (P < .05) from male cohorts; **different (P < .01) from
male cohorts; ‡different (P < .0001) from male cohorts; a = different
(P < .05) from non-Hispanic Whites; b = different (P < .01) from non-
Hispanic Whites; c = different (P < .001) from non-Hispanic Whites;
d = different (P < .0001) from non-Hispanic Whites; x = different (P
< 0.05) from overweight; z = different (P < .0001) from overweight.
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880 Clinical Pediatrics 49(9)
odds of developing abdominal obesity increased (P <
.01) by a factor of 1.46 and 1.61, respectively (Table 2).
Although not significant (at P < .05), Hispanic and Afri-
can American females exhibited increasing trends (35%
and 49%, respectively) of developing abdominal obesity
compared to non-Hispanic white females (Table 2).
Systolic Blood Pressure
Independent of ethnicity/race, mean SBP was 9% greater
(P < .001) in males (124 ± 1 mm Hg) than females (113 ±
1 mm Hg). The overall prevalence of pre-elevated SBP
and elevated SBP was 11.5% (9.6% to 12.4%) and 17.8%
(16.3% to 19.7%), respectively. Collectively, males had
a higher (P < .01) prevalence of pre-elevated SBP
(14.4%; [11.8% to 16.2%] vs 8.4%; [7.1% to 10.9%])
and elevated SBP (25.5%; [22.3% to 27.7%] vs 9.4%;
[8.1% to 12.0%]) than females, respectively (Figures 2A
and 2B). Accounting for ethnicity/race, the prevalence
of elevated SBP was higher (P < .001) in males than
their female cohorts (Figure 2B). Among males, the
prevalence of pre-elevated SBP and elevated SBP was
not different from non-Hispanic whites (Figure 2A).
However, the prevalence of elevated SBP was approxi-
mately 2-fold greater (P < .001) than that of pre-elevated
SBP among all groups of males (Figure 2A).
Among females, the prevalence of pre-elevated SBP
was not different among any of the groups; however, the
prevalence for elevated SBP in African-Americans
(13.2%; 10.8% to 15.2%) was higher (P < .05) than that
in non-Hispanic whites (9.2%; 5.4% to 12.6%; Figure 2B).
Table 2. Adjusted Odds Ratios (95% Confidence Interval) by Race/Ethnicity and Gender Using Logistic Regressiona
Total Population Male Female
BMI: normal vs overweight
White 1 1 1
Hispanic 1.16 (0.94-1.43) 1.12 (0.88-1.43) 1.18 (0.88-1.58)
African American 1.37 (0.87-2.17) 1.28 (0.69-2.34) 1.45 (0.76-2.81)
Male 1.05 (0.86-1.29) — —
BMI: normal vs obese
White 1 1 1
Hispanic 1.23 (1.00-1.51) 2.11b (1.71-2.63) 1.01 (0.72-1.41)
African American 1.69c (1.11-2.57) 2.50b (1.51-4.16) 1.79 (0.91-3.54)
Male 2.38b (1.94-2.92) — —
BMI: overweight vs obese
White 1 1 1
Hispanic 1.04 (0.81-1.35) 1.88b (1.43-2.47) 0.86 (0.57-1.27)
African American 1.24 (0.74-210) 1.96d (1.03-3.74) 1.23 (0.55-2.76)
Male 2.26b (1.76-2.92) — —
WC: normal vs obese
White 1 1 1
Hispanic 1.46c (1.16-1.84) 1.59b (1.25-2.02) 1.35 (0.96-1.91)
African American 1.61d (1.03-2.51) 1.74d (1.00-3.00) 1.49 (0.74-3.01)
Male 1.34c (1.07-1.67) — —
aBody mass categories are based on body mass index (BMI) or waist circumference (WC). WC £ 90th percentile is the baseline outcome.
bP < .001.
cP < .01.
dP < .05.
Table 3. Predicted Probabilities (%) for Obesity by Race/
Ethnicity Using Logistic Regressionsa
Male Female
BMI: normal vs overweight
White 23.2 22.1
Hispanic 25.6 24.9
African American 29.3 30.5
BMI: normal vs obese
White 31.9 18.9
Hispanic 37.6 17.7
African American 44.5 26.2
BMI: overweight vs obese
White 60.8 45.3
Hispanic 63.7 39.4
African American 65.9 44.7
WC: normal vs obese
White 15.8 14.8
Hispanic 23.1 17.2
African American 29.2 20.0
aBody mass categories are based on body mass index (BMI) or waist
circumference (WC).
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Rodriguez et al. 881
A difference (P < .05) in the prevalence between pre-
elevated SBP and elevated SBP among females was
only detected in African Americans (Figure 2B).
The adjusted odds ratio logistic regressions identified
significant gender and weight category effects for both
pre-elevated and elevated SBP (Figures 3A and 3B).
Whereas overweight males did not exhibit increased
odds of developing pre-elevated SBP, the odds were
increased in overweight females (2.2-fold), and obese
males (2.6-fold) and females (3.9-fold; Figure 3A). Inde-
pendent of gender, overweight adolescents were only
1.7-fold more likely (P < .01), but obese adolescents
were more than 3-fold more likely (P < .001) of develop-
ing pre-elevated SBP (Figure 3A). The odds of develop-
ing elevated SBP were greatest (P < .001) in overweight
and obese females, with the odds nearly 9-fold in obese
females (Figure 3B). Independent of gender, the odds
of developing elevated SBP were 2.1-fold greater in
overweight adolescents, and the odds increase to 5.5-fold
greater in obese adolescents (Figure 3B).
Correlations
WC and BMI were both correlated with SBP in all male
and female adolescent groups with the exception of
African American females. Because y-intercepts and
slopes were not different among different ethnicities/
race and gender, the data were combined (excluding that
for African American females) to generate the following
correlations: SBP = 95 + 0.297 * WC (R = .333; P < .01)
and SBP = 102 + 0.702 * BMI (R = .312; P < .001).
Discussion
Childhood and adolescent obesity are critical public
health concerns because of the comorbidity with other
0
10
20
30
40
Prevalence (%)
Pre-Elevated SBP
Elevated SBP
A
zd,z
d,z
0
10
20
30
40
Whites Hispanics African-Americans
Prevalence (%)
B
ǂ
ǂ,a,x
ǂ
Figure 2. Prevalence (lower-upper 95% confidence
intervals) of pre-elevated systolic blood pressure (SBP; open
bars) and elevated SBP (shaded bars) in adolescents by
ethnicity/race for (A) males and (B) females
‡Different (P < .0001) from male cohorts; a = different (P < .05) from
non-Hispanic Whites; x = different (P < .05) from pre-elevated SBP;
z = different (P < .0001) from pre-elevated SBP.
1.1
2.0 1.5
2.5
7.0
3.0
2.4
4.8 4.0
5.1
16.2
7.4
2.1
3.7
1.6
5.5
8.8
3.5
0
2
4
6
8
10
12
14
16
18
20
***
*
***
***
***
***
B
Males Females Combined
0.7 1.4 1.4
2.1
4.7
3.0
1.4 2.1 2.1
3.4
7.5
4.4
1.2
2.6 1.7
2.2
3.9
3.1
0
2
4
6
8
10
12
14
16
18
20
Overweight
Obese
***
***
** ***
**
A
Figure 3. Adjusted odds ratio (lower-upper 95% confidence
intervals) of logistic regressions for (A) pre-elevated systolic
blood pressure (SBP) and (B) elevated SBP resulting from
overweight and obesity (as defined by body mass index
[BMI]) by gender
SBP ≤ 90th percentile was used as the baseline outcome. *P < .05,
**P < .01, ***P < .001.
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882 Clinical Pediatrics 49(9)
metabolic pathologies. Unfortunately, the data on obe-
sity and elevated blood pressure are virtually nonexis-
tent for adolescents from rural predominantly minority
communities. A major contribution of the present study
is the prevalence data of overweight, obesity, abdominal
obesity, and elevated SBP in adolescents from a rural,
predominately minority population because the majority
of anthropometric data of children and adolescents come
from sample populations in large metropolitan areas or
national surveys. It was expected that minority groups in
a rural community would have a greater prevalence of
both overweight and obesity. Because of the scarcity of
data on WC in adolescents, and the relationships between
BMI, WC, and SBP, we also examined these relation-
ships to better ascertain how these measures of body
condition correlate with elevated SBP. The present study
demonstrates that the overall prevalence of overweight
and obesity in adolescents in our study population was
41.2%, which is 21.2% higher than the highest, and 3.6-
fold higher than the lowest reported values from national
surveys of large metropolitan sample populations, Cali-
fornia sample populations and international sample pop-
ulations.1-3,5,6, 11-13
An important finding of the present study is that the
prevalence of obesity is greater than that for overweight
in adolescent males, regardless of ethnicity/race. The
prevalence of obesity (29.4%) surpassed the prevalence
of overweight (17.5%) in all males. This difference was
greatest in African Americans followed by Hispanics,
and non-Hispanic whites. Regardless of ethnicity/race,
the prevalence of obesity was consistently nearly 2-fold
greater than that for overweight in males, suggesting that
factors beyond culture are contributing to this disturbing
trend. To the best of our knowledge this is the first study
to report such a difference in adolescent males across
racial/ethnic groups. A previous study that only exam-
ined Latino adolescents of mostly El Salvadorian descent
demonstrated similar results, but with a smaller magni-
tude of difference.30 Because of this greater prevalence
of obesity than overweight, minority adolescent males
from a rural population may be at a greater risk of weight-
dependent metabolic disorders later in life. The interest-
ing finding that the prevalence of obesity was greater
than that of overweight only in males regardless of race/
ethnicity suggests that the disparity is gender specific
and not likely the result of cultural differences.
A majority of studies report that African American
and Hispanic adolescents have a higher incidence and
prevalence of overweight and obesity compared to non-
Hispanic white adolescents.1,3-6 Our prevalence data for
obesity in males supports this claim and is further rein-
forced by the logistic regressions, which demonstrates
that both Hispanic and African American adolescents
have greater odds of being obese than non-Hispanic
whites. However, the fact that the prevalence of obesity
was nearly twice that for overweight in all males sug-
gests that non-Hispanic white adolescents in rural, dis-
advantaged communities may have increased risk of
developing metabolic and CV complications than cohorts
from urban communities. The similarities in the preva-
lence of overweight across the multiple ethnic groups
suggests that community factors and not just genetic and/
or cultural differences are contributing to early progres-
sion of increased body mass, which from the perspective
of public health warrants further investigation.
Another important finding is the relatively high prev-
alence of abdominal obesity (18.4%). African Ameri-
cans and Hispanics had higher prevalence compared
with non-Hispanic whites, suggesting that health dispari-
ties may exist in our population using WC as the metric.
These values are approximately 2-fold greater than those
previously reported (7.6% for African Americans; 11.4%
for Hispanics; 6% for White, non-Hispanics),28 suggest-
ing that the prevalence of abdominal obesity is much
greater in our population that may not be well represented
in large national surveys. This same study reported that
abdominal obesity accounted for part of the upward
trend in high blood pressure.28 Increased WC and BMI
both positively correlated with SBP in all male and
female adolescent groups with the exception of African
American females. This supports the growing body of
evidence that WC may provide a reliable index of CV
risk in certain adolescent groups.15,18,19,31 Although
increased WC is a strong predictor of CV disease in
adult African Americans,16,17 neither WC nor BMI cor-
related with SBP in adolescent African American
females suggesting that other factors contribute to their
prevalence of elevated SBP (13.8%). We suggest that
because certain anthropometric measurements may not
possess the same predictive value for obesity in adoles-
cents across ethnicities/races, it highlights the need to
evaluate the multitude of potential factors that contrib-
ute to the risk of CV disease and metabolic disorders in
adolescents from minority populations.
We also demonstrate that the prevalence of obesity
among different groups of adolescents can be skewed
based on how obesity is defined. When obesity was
assessed using BMI ≥95th percentile, the collective prev-
alence was 22.3%, with males higher than females (29.4%
vs 14.5%, respectively). When abdominal obesity was
assessed using WC ≥90th percentile, the collective preva-
lence was 18.4%, with males greater than females (19.5%
vs 15.5%, respectively). Assessing the prevalence of obe-
sity using WC consistently underestimated the prevalence
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Rodriguez et al. 883
of obesity when compared to using BMI. This suggests
the need to develop a new metric that incorporates both
BMI and WC measurements to create a better assess-
ment of adiposity.
The prevalence of hypertension in adolescents ranges
between 2.2% and 7.4% when based on multiple mea-
surements.5,13,32 Although we report values based on a
single measurement, we are cognizant of the fact that
multiple measurements over time provide a better diag-
nostic value. Nonetheless, the collective prevalence of
elevated SBP in our study was 17.8%, with the highest
prevalence (18.1%) among Hispanic adolescents. This
is consistent with previous research where the preva-
lence of elevated blood pressure was 19.4% overall, and
the highest prevalence among Hispanics (25%) and
non-Hispanic whites (18%) after the first screening.5
Combined, these data demonstrate a relatively high prev-
alence of pre-elevated and elevated SBP in adolescents.
This is disconcerting because studies have shown that
high blood pressure early in life is associated with the
manifestation of hypertension and coronary heart dis-
ease in adulthood.33,34 Obese females also had the high-
est odds of developing pre-elevated (4-fold) and elevated
SBP (8-fold) compared to normal-weight cohorts sug-
gesting that adiposity may exert a greater impact on SBP
in adolescent females than males.
Conclusions
The prevalence of obesity in adolescent males is greater
(in some cases almost 2-fold) than that of overweight in
our study population, which represents a rural, disadvan-
taged community. This suggests that adolescent males
from small rural communities may be at greater risk for
developing CVD and other metabolic disorders during
adulthood. The relatively high prevalence of elevated
SBP in these groups exacerbates the risk of metabolic
and CV complications. Adolescents in our study popula-
tion also exhibited a higher prevalence of abdominal
obesity than adolescents from urban or nationally repre-
sentative samples suggesting that adolescents from rural
communities may be at even a greater risk for develop-
ing CV complications than their counterparts in larger
metropolitan communities. The implementation of inter-
vention and prevention strategies early in life is impera-
tive to decrease the chances of this population from
developing weight-dependent metabolic disorders. The
present study also highlights the importance of WC to
identify the potential risk for developing CV complica-
tions in minority males from rural populations. Imple-
menting the routine measure of WC in adolescents may
also prove to be valuable when assessing the risk of
developing metabolic disorders. A newly defined metric
that incorporates both BMI and WC values may provide
a better representation of body condition (adiposity) than
either term independently, and a better assessment of
developing metabolic complications.
Author’s Note
This research was approved by the University of Cali-
fornia, Merced, Institutional Review Board.
Acknowledgment
We would like to thank Mrs D. Conte, Ms A. Camelo,
MUHSD nursing staff, and all the physicians who
assisted with the health assessments and sports physi-
cals. We also thank Drs A. Song (UC Merced), J. Wal-
lander (UC Merced), and P. Crawford (UC Berkeley)
for their review of and comments on this article.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest
with respect to the authorship and/or publication of this
article.
Funding
This research was funded by Millennium Sports Club,
Great Valley Center (GVC), and University of California
startup funds. R. Rodriguez and J. Mowrer were sup-
ported by a GVC fellowship.
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