Gender Difference in Blood Pressure Control and
Cardiovascular Risk Factors in Americans
With Diagnosed Hypertension
Kwok Leung Ong, Annette W.K. Tso, Karen S.L. Lam, Bernard M.Y. Cheung
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Abstract—Hypertension is an important risk factor for cardiovascular disease, which is the leading cause of death in
women. We, therefore, analyzed gender-specific trends in the control of blood pressure and prevalence of 5 other
cardiovascular risk factors (central obesity, elevated total cholesterol, low high-density lipoprotein cholesterol,
hyperglycemia, and smoking) among adults with diagnosed hypertension in the United States. We included 3475
participants aged ⱖ18 years with diagnosed hypertension in the National Health and Nutrition Examination Survey
1999 –2004. The age-adjusted prevalence of uncontrolled blood pressure was 50.8⫾2.1% in men and 55.9⫾1.5% in
women, which were not significantly different and had not changed significantly with time. Central obesity, elevated
total cholesterol level, and low high-density lipoprotein cholesterol were significantly more prevalent in women than in
men (79.0⫾1.0%, 61.3⫾1.6%, and 39.7⫾1.6% versus 63.9⫾1.6%, 48.1⫾1.8%, and 35.6⫾1.7%, respectively;
P⬍0.05). The age-adjusted proportion with ⱖ3 of the 6 risk factors studied was higher in women than in men
(52.5⫾1.4% versus 40.9⫾1.8%; P⬍0.001), and this proportion decreased significantly by 7.7% in women from
1999 –2000 to 2003–2004 (P⬍0.05) but not in men. Our study shows that blood pressure control in women with
diagnosed hypertension was not significantly inferior compared with men and had not changed significantly in
1999 –2004. However, women had higher prevalence of other concomitant cardiovascular risk factors. Although there
is room for improvement in blood pressure control, our study has highlighted the importance of addressing concomitant
cardiovascular risk factors in women with hypertension. (Hypertension. 2008;51:1-7.)
Key Words: cardiovascular risk factors 䡲 control 䡲 gender difference 䡲 hypertension 䡲 United States
H
ypertension is a disease of complex etiology, affecting
972 million people worldwide.1 It is estimated that the
worldwide prevalence of hypertension would increase from
26.4% in 2000 to 29.2% in 2025.1 Hypertension is an
important risk factor for cardiovascular disease and has
become a major global burden on public health.2 In 2003–
2004, 76.9% US adults with cardiovascular disease comorbidities had hypertension.3 Because cardiovascular disease is
the leading cause of death in women,4,5 there is a need to
improve our understanding of the factors that influence blood
pressure control in women with hypertension.
Other than hypertension, cigarette smoking, hypercholesterolemia, low high-density lipoprotein cholesterol (HDL),
and diabetes are also major risk factors for cardiovascular
diseases.6,7 Hypertension clusters with obesity, dyslipidemia,
and elevated glucose level. The presence of these metabolic
risk factors correlates with uncontrolled blood pressure and
augments the cardiovascular risk in hypertensive individuals.8
Therefore, blood pressure control needs to be considered in
conjunction with the control of other concomitant cardiovas-
cular risk factors. We previously reported an improvement in
blood pressure control rates among all adults with hypertension and among those with drug treatment in the United
States from 1999 –2000 to 2003–2004.9 However, blood
pressure control rates among people with diagnosed hypertension were not examined in previous reports,9 –11 and there
are few reports on the prevalence of other cardiovascular risk
factors in these people in a large, nationally representative
sample population. In this study, we used the latest data from
the US National Health and Nutrition Examination Survey
(NHANES) 1999 –2004 to determine, among people with
diagnosed hypertension, the gender difference in blood pressure control, prevalence of other concomitant cardiovascular
risk factors, and factors that may influence blood pressure
control.
Methods
Study Design
NHANES was conducted by the National Center for Health Statistics
of the Centers for Disease Control and Prevention to monitor the
Received November 14, 2007; first decision December 6, 2007; revision accepted January 7, 2008.
From the Department of Medicine (K.L.O., A.W.K.T., K.S.L.L., B.M.Y.C.), University of Hong Kong, Hong Kong; and the Department of Clinical
Pharmacology (B.M.Y.C.), Division of Medical Sciences, University of Birmingham, Birmingham, UK.
Correspondence to Bernard M.Y. Cheung, Department of Clinical Pharmacology, Division of Medical Sciences, University of Birmingham,
Birmingham B15 2TH, United Kingdom. E-mail [email protected]
© 2008 American Heart Association, Inc.
Hypertension is available at http://hyper.ahajournals.org
DOI: 10.1161/HYPERTENSIONAHA.107.105205
1
2
Hypertension
April 2008
health and nutritional status of the civilian, noninstitutionalized US
population.12 All of the participants gave informed consent, and the
study received approval from the Centers for Disease Control and
Prevention Institutional Review Board. Participants were defined to
have diagnosed hypertension if they self-reported diagnosed hypertension and had a blood pressure ⱖ140/90 mm Hg or were taking
antihypertensive medications. In NHANES 1999 –2004, there were
8307 women and 7564 men aged ⱖ18 years who were both
interviewed and examined in the mobile examination center. After
excluding 862 pregnant women and 788 subjects with missing blood
pressure data, there were 6989 women and 7232 men. Among them,
2501 women and 2335 men had hypertension, of whom 1858 women
and 1617 men had been diagnosed previously and were aware of
their hypertension. Therefore, a total of 3475 participants with
diagnosed hypertension were included in the analysis. Additional
details are described in the supplementary Methods section (please
see http://hyper.ahajournals.org).
Blood Pressure Control
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Uncontrolled blood pressure was defined as blood pressure ⱖ140/
90 mm Hg in nondiabetic persons and ⱖ130/80 mm Hg in diabetic
persons according to the Seventh Report of the Joint National
Committee on Prevention, Detection, Evaluation, and Treatment of
High Blood Pressure (JNC 7).13 In a separate analysis, we assessed
the prevalence of uncontrolled blood pressure using the cut points of
blood pressure ⱖ140/90 mm Hg for nondiabetic persons and ⱖ130/
85 mm Hg for diabetic persons according to the previous JNC 6
guidelines.14 Participants were considered to have diabetes if they
had been diagnosed previously by a doctor or if they were receiving
insulin or oral antidiabetic medications.
Cardiovascular Risk Factors
Central obesity was defined according to the National Cholesterol
Education Program-Adult Treatment Panel III.15 In a separate
analysis, central obesity was also assessed using the ethnic-specific
waist circumference cut points according to the International Diabetes Federation.16 Low HDL was defined as a level ⬍50 mg/dL in
men and ⬍40 mg/dL in women.15 Because data on fasting glucose,
triglycerides, and low-density lipoprotein cholesterol were available
only in a subsample of fasting subjects, we assessed glycosylated
hemoglobin level (HbA1c) and total cholesterol level instead. Elevated HbA1c was defined as a level ⱖ7.0%.17 Elevated total cholesterol level was defined as a level ⱖ200 mg/dL.15 Additional details
are described in the supplementary Methods section.
Other Variables of Interest
Information on race/ethnicity, education, health insurance, smoking,
and history of hypertension, including blood pressure control methods, was obtained from self-reported questionnaires. Body mass
index was calculated as weight in kilograms divided by the square of
height in meters. Pregnancy was determined by a self-reported
questionnaire and a urine pregnancy test. Women not having a
menstrual period in the past 12 months were defined as having had
menopause. Albuminuria was defined as a urinary albumin:creatinine ratio ⱖ30 mg/g. Additional details are described in the
supplementary Methods section.
Statistical Analysis
Data were analyzed using the complex sample function of SPSS
version 15.0 (SPSS Inc) and SAS version 9.0 (SAS Institute Inc).
The blood pressure control rates and prevalence of cardiovascular
risk factors were age adjusted by direct standardization to the
NHANES 1999 –2004 population with diagnosed hypertension. To
analyze the trends over time, multiple linear or logistic regression
models were used, in which the survey (NHANES 1999 –2000,
2001–2002, and 2003–2004) was included as an independent ordinal
variable. Multiple logistic regression was used to assess the independent associations of potential factors with blood pressure control.
Interactions between potential factors and gender for blood pressure
control were assessed by including each multiplicative interaction
term in the multivariate logistic regression models in the full sample
after adjusting for the main effects of confounding factors. Additional details are described in the supplementary Methods section.
Results
Among people with diagnosed hypertension in NHANES
1999 –2004, 54.9⫾1.2% (mean⫾SE) were women. The ageadjusted proportion of women did not change significantly in
this period, from 54.4⫾1.9% in 1999 –2000 to 58.3⫾1.9% in
2001–2002 and to 50.7⫾2.1% in 2003–2004 (P for
trend⫽0.061 after adjusting for age and race or ethnicity).
Table 1 shows the gender-specific characteristics of people
with diagnosed hypertension in NHANES 1999 –2004. Compared with men, women were older, more likely to have a
higher body mass index and be non-Hispanic black and less
likely to be non-Hispanic white. There was an increase in the
level of education in both men and women between 1999 –
2000 and 2003–2004. There had been a significant increase in
the prevalence of diabetes in women over the period 1999 –
2004 so that, overall, the prevalence of diabetes was not
significantly different in men and women. The prevalence of
microalbuminuria was significantly lower in women and
decreased significantly in women but not men during the
study period. Women were more likely than men to have their
blood pressure checked by a doctor in the last 6 months. Men
were more likely to use reduction of alcohol intake to control
blood pressure, although this percentage had decreased significantly between 1999 –2000 and 2003–2004. The use of
other methods for blood pressure control did not differ by
gender nor change with time. A detailed version of Table 1 is
given in supplementary Table S1.
Table 2 shows the gender-specific blood pressure control
rates and prevalence of cardiovascular risk factors among
people with diagnosed hypertension in NHANES 1999 –
2004. In NHANES 1999 –2004, women had higher mean
systolic but lower mean diastolic blood pressure than men.
During this period, diastolic blood pressure decreased significantly in both men and women, whereas systolic blood
pressure decreased significantly in women only. However,
the age-adjusted prevalences of uncontrolled blood pressure,
50.8⫾2.1% in men and 55.9⫾1.5% in women, were not
significantly different and had not changed significantly with
time. If blood pressure targets in the JNC 6 guidelines were
used, then the prevalence of uncontrolled blood pressure
among all of the people with diagnosed hypertension decreased significantly with time after adjustment (P for
trend⫽0.04 after adjusting for age, sex, and race or ethnicity;
Table S2).
The prevalence of central obesity (either National Cholesterol Education Program-Adult Treatment Panel III or International Diabetes Federation definition), elevated total cholesterol level, and low HDL was significantly higher in
women than in men (P⬍0.001, P⬍0.001, and P⫽0.042 after
adjusting for age and race or ethnicity, respectively; Table 2).
The prevalence of central obesity did not change significantly
with time in either gender. However, total cholesterol decreased significantly among all of the people, particularly in
women (Table S2). In 1999 –2004, the mean HDL increased
and the prevalence of low HDL decreased among all of the
Ong et al
Table 1.
Cardiovascular Risk Factors in Hypertensive Adults
3
Characteristics of People With Diagnosed Hypertension in NHANES 1999 –2004
Change, 1999 –2000 to 2003–2004,
Difference (95% CI)
1999 –2004
Characteristics
Men
n
Women
Men
Women
1617
1858
NA
NA
57.68 (0.49)
62.31 (0.43)†
1.20 (⫺1.64 to 4.05)
0.59 (⫺1.02 to 2.19)
Non-Hispanic white
77.2 (2.0)
71.8 (2.4)†
1.6 (⫺7.6 to 10.9)
3.1 (⫺9.5 to 15.8)
Non-Hispanic black
11.9 (1.1)
16.7 (2.2)†
Mexican American
3.7 (0.9)
3.6 (0.8)
24.3 (1.3)
27.9 (1.4)
Age, mean (SE), y
Race or ethnicity, % (SE)
Less than high school education, % (SE)
2
Body mass index, mean (SE), kg/m
⫺1.2 (⫺6.6 to 4.1)
0.8 (⫺9.1 to 10.7)
0.8 (⫺3.7 to 5.3)
⫺7.1 (⫺13.8 to ⫺0.5)‡
0.36 (⫺0.54 to 1.26)
0.1 (⫺4.2 to 4.5)
⫺10.8 (⫺18.7 to ⫺2.9)‡
⫺0.89 (⫺1.98 to 0.20)
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30.21 (0.20)
31.10 (0.20)†
Health insurance, % (SE)
91.8 (0.8)
92.3 (0.8)
⫺1.6 (⫺5.6 to 2.3)
0.7 (⫺3.5 to 4.9)
Diabetes, % (SE)
18.7 (1.1)
18.3 (0.9)
4.3 (⫺1.1 to 9.7)
5.3 (0.1 to 10.6)‡
Microalbuminuria, % (SE)
21.5 (1.0)
18.2 (1.0)*
⫺1.7 (⫺6.7 to 3.2)
Blood pressure checked by doctor within
last 6 mo, % (SE)
88.6 (1.0)
92.5 (0.7)*
3.4 (⫺1.5 to 8.3)
Take drug, mean
84.4 (1.2)
87.3 (1.1)
⫺0.4 (⫺6.8 to 6.0)
Control weight, mean
43.7 (1.6)
41.4 (1.6)
0.2 (⫺7.4 to 7.9)
⫺1.5 (⫺10.1 to 7.2)
Reduce salt/sodium intake, mean
57.7 (1.7)
61.0 (1.5)
⫺2.4 (⫺10.2 to 5.4)
⫺3.0 (⫺10.3 to 4.3)
Exercise, mean
41.2 (1.5)
38.1 (1.5)
0.5 (⫺7.5 to 8.4)
⫺6.1 (⫺13.7 to 1.4)
Reduce alcohol, mean
24.1 (1.5)
15.9 (1.3)‡
⫺11.3 (⫺19.1 to ⫺3.5)§
⫺3.8 (⫺9.8 to 2.3)
⫺6.8 (⫺11.9 to ⫺1.7)‡
0.1 (⫺4.0 to 4.1)
Methods of blood pressure control, % (SE)
2.2 (⫺2.9 to 7.2)
Data are age adjusted by direct standardization to the NHANES 1999 –2004 population with diagnosed hypertension, except for age-specific
estimates. NA indicates not applicable.
*P⬍0.01 and †P⬍0.001 for gender difference and ‡P ⬍0.05 and §P⬍0.01 for time trend after adjusting for age (except for age-specific estimates)
and race or ethnicity (except for race or ethnicity-specific estimates).
people (Table S2). In men, there was a significant 13.2%
decrease in the age-adjusted prevalence of low HDL and in
women, the age-adjusted mean HDL increased significantly
by 3.6 mg/dL (Table 2).
Among people with diagnosed hypertension, the ageadjusted proportion with ⱖ3 of the 6 risk factors studied was
higher in women than in men (52.5⫾1.4% versus
40.9⫾1.8%; P⬍0.001 after adjusting for age and race or
ethnicity), although this proportion decreased significantly in
women from 57.3% in 1999 –2000 to 49.6% in 2003–2004
(P⫽0.049 after adjusting for age and race or ethnicity) but not
in men (Table S3). Women had more risk factors than men
both among people with uncontrolled blood pressure and
those with controlled blood pressure (Table S3).
Among women with diagnosed hypertension in NHANES
1999 –2004, the proportion of postmenopausal women was
82.8⫾1.3%. The prevalence of uncontrolled blood pressure,
central obesity, low HDL, and elevated HbA1c level did not
differ significantly by menopause status after adjusting for
age and race or ethnicity (data not shown). However, postmenopausal women had a significantly higher prevalence of
elevated total cholesterol (unadjusted prevalence: 64.1⫾1.7%
versus 48.9⫾3.9%; P⫽0.01 after adjusting for age and race
or ethnicity) but a lower proportion of current smoking
(unadjusted proportion: 12.7⫾1.1% versus 19.9⫾2.7%;
P⫽0.002 after adjusting for age and race or ethnicity).
To assess the factors independently associated with blood
pressure control in people with diagnosed hypertension,
multiple logistic regression was performed with blood pressure control (according to JNC 7 criteria) as the dependent
variable. Increasing age, being non-Hispanic black, and
diabetes were significantly associated with uncontrolled
blood pressure, whereas taking antihypertensive drugs and
current smoking were associated with better control (Table
3). Not having blood pressure reading checked by a doctor
within the past 6 months, having weight control, and higher
total cholesterol level were associated significantly with
uncontrolled blood pressure in women but not in men. In
men, current smoking was associated with better control.
However, only age and exercise showed significant interactions with gender for blood pressure control among all of the
subjects (P for interaction⫽0.023 and 0.038 after adjusting
for the main effects of all covariates, respectively). The
presence of risk factors other than elevated blood pressure
was associated with uncontrolled blood pressure in women
only (P⫽0.030), when central obesity was defined according
to the National Cholesterol Education Program-Adult Treatment Panel III definition (Table S4).
Discussion
This study reported the recent trends in blood pressure
control and prevalence of cardiovascular risk factors
among people with diagnosed hypertension in NHANES
1999 –2004. In this study, we found that blood pressure
control rates were not significantly lower in women and
have excluded a large gender difference in this respect.
4
Hypertension
April 2008
Table 2. Blood Pressure Control and Cardiovascular Risk Factors Among People With Diagnosed
Hypertension in NHANES 1999 –2004
Change, 1999 –2000 to 2003–2004,
Difference (95% CI)
1999 –2004
Outcome Measures
Men
Women
Men
Women
Blood pressure
n
1617
1858
Systolic, mean (SE), mm Hg
136.0 (0.7)
140.1 (0.7)‡
Diastolic, mean (SE), mm Hg
75.6 (0.5)
Uncontrolled blood pressure, % (SE)¶
50.8 (2.1)
NA
NA
⫺2.7 (⫺6.2 to 0.7)
⫺3.8 (⫺7.1 to ⫺0.4)§
72.1 (0.4)‡
⫺3.1 (⫺5.3 to ⫺0.9)§
⫺3.2 (⫺5.6 to ⫺0.8)储
55.9 (1.5)
⫺3.3 (⫺14.0 to 7.4)
⫺7.5 (⫺14.8 to ⫺0.2)
Waist circumference
n
1542
1768
NA
107.9 (0.5)
101.3 (0.5)‡
1.7 (⫺0.6 to 4.0)
NCEP-ATPIII definition
63.9 (1.6)
79.0 (1.0)‡
8.8 (0.8 to 16.8)
IDF definition
86.2 (1.0)
92.8 (0.7)‡
⫺1.4 (⫺5.2 to 2.5)
Mean (SE), cm
NA
⫺0.1 (⫺2.7 to 2.6)
Central obesity, % (SE)
2.4 (⫺2.5 to 7.4)
⫺1.8 (⫺5.9 to 2.3)
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Total cholesterol
n
Mean (SE), mg/dL
ⱖ200 mg/dL, % (SE)
1544
1726
NA
201.8 (1.6)
212.9 (1.4)‡
⫺6.7 (⫺13.2 to ⫺0.2)
⫺6.3 (⫺12.9 to 0.4)§
NA
48.1 (1.8)
61.3 (1.6)‡
⫺9.9 (⫺18.5 to ⫺1.3)
⫺9.3 (⫺18.2 to ⫺0.3)§
HDL
n
1544
1727
NA
Mean (SE), mg/dL
46.0 (0.4)
56.5 (0.4)‡
2.1 (⫺0.1 to 4.4)
3.6 (1.4 to 5.8)§
NA
⬍40 mg/dL in men or ⬍50 mg/dL
in women, % (SE)
35.6 (1.7)
39.7 (1.6)*
⫺13.2 (⫺21.4 to ⫺5.0)储
⫺5.0 (⫺12.0 to 2.0)
HbA1c
n
1559
1777
NA
NA
Mean (SE), %
5.89 (0.04)
5.83 (0.03)
0.05 (⫺0.14 to 0.23)
0.05 (⫺0.13 to 0.23)
ⱖ7.0%, % (SE)
11.1 (0.9)
9.8 (0.9)
⫺2.9 (⫺6.3 to 0.5)
⫺1.6 (⫺6.5 to 3.4)
Current smoking
n
% (SE)
1615
1858
NA
18.7 (1.3)
15.1 (1.1)
4.5 (⫺2.1 to 11.0)
NA
1.2 (⫺4.1 to 6.6)
Data are age-adjusted by direct standardization to the NHANES 1999 –2004 population with diagnosed hypertension. NA indicates
not applicable; NCEP-ATPIII, National Cholesterol Education Program-Adult Treatment Panel III; IDF, International Diabetes Federation.
*P⬍0.05, †P⬍0.01, and ‡P⬍0.001 for gender difference and §P ⬍0.05 and 储P⬍0.01 for time trend after adjusting for age and
race/ethnicity.
¶Blood pressure ⱖ140/90 mm Hg in nondiabetic patients and ⱖ130/80 mm Hg in diabetic patients according to JNC 7 guidelines.
However, women tended to have more cardiovascular risk
factors than men, including central obesity, elevated total
cholesterol, and low HDL. Although on average, women
had a lower diastolic blood pressure than men, women had
a higher systolic blood pressure, which is a better predictor
of the risk of cardiovascular and renal disease than
diastolic blood pressure.18 On the positive side, along with
decreases in systolic and diastolic blood pressures, there
have been improvements in microalbuminuria, total cholesterol, HDL, and also the number of cardiovascular risk
factors present. These changes were especially notable in
women.
In NHANES III (1988 –1994), the male gender was associated with uncontrolled blood pressure and lack of awareness of hypertension in multivariate analysis.19 Although
women had higher awareness and control rates than men in
1988 –1994, these differences were no longer significant in
1999 –2000.10 There was an increase in the use of any
hypertensive medications in men but not women between
1988 –1994 and 1999 –2002.20 The blood pressure control
rate also increased in men but not women between 1988 –
1994 and 1999 –2000.10 These may account for the observation that the male gender was not associated with uncontrolled blood pressure in the period 1999 –2004. Our finding
differs from some reports showing gender difference in blood
pressure control.21 It has been suggested that sex hormones
may contribute to the gender difference in blood pressure
regulation.22 It is likely that androgens but not estrogens are
the major contributing factor, because androgens could increase blood pressure, whereas studies on hormone replacement therapy shows no or slight effect on blood pressure in
postmenopausal women.22 In the Rancho Bernardo Study, the
total serum testosterone increased with age in women with
intact ovaries, demonstrating that testosterone may have a
Ong et al
Cardiovascular Risk Factors in Hypertensive Adults
5
Table 3. Multiple Logistic Regression Analysis of Factors Associated With Blood Pressure Control Among People With
Diagnosed Hypertension in NHANES 1999 –2004
Odds Ratio (95% CI)
Factors
Men (n⫽1453)
Women (n⫽1571)
All (n⫽3073)
0.85 (0.74 to 0.98)*
0.69 (0.61 to 0.78)‡
0.75 (0.69 to 0.81)‡
NA
NA
0.84 (0.68 to 1.03)
Non-Hispanic black
0.61 (0.42 to 0.90)*
0.68 (0.50 to 0.92)*
0.67 (0.54 to 0.83)‡
Mexican American
0.70 (0.39 to 1.26)
0.85 (0.59 to 1.24)
0.81 (0.58 to 1.14)
Diabetes (referent: no)
0.37 (0.25 to 0.55)‡
0.41 (0.26 to 0.67)‡
0.40 (0.30 to 0.54)‡
Last blood pressure reading by doctor ⬍6
mo ago (referent: no)
1.10 (0.52 to 2.31)
2.94 (1.35 to 6.43)†
1.69 (0.99 to 2.88)
7.03 (4.92 to 10.04)⫻1013‡
6.12 (3.87 to 9.67)⫻1013‡
1.76 (1.35 to 2.29)⫻1014‡
Control weight (referent: no)
1.30 (0.79 to 2.14)
0.67 (0.51 to 0.87)†
0.91 (0.70 to 1.18)
Reduce salt/sodium intake (referent: no)
0.96 (0.68 to 1.36)
0.90 (0.67 to 1.23)
0.92 (0.72 to 1.18)
Exercise (referent: no)
0.81 (0.54 to 1.20)
1.27 (0.96 to 1.69)
1.04 (0.82 to 1.31)
Reduce alcohol (referent: no)
1.05 (0.75 to 1.50)
1.23 (0.87 to 1.73)
1.13 (0.86 to 1.49)
0.99 (0.96 to 1.03)
0.97 (0.94 to 1.00)*
0.98 (0.95 to 1.01)
Former
1.46 (0.98 to 2.17)
1.23 (0.85 to 1.80)
1.35 (1.06 to 1.72)*
Current
2.23 (1.38 to 3.59)†
1.11 (0.72 to 1.71)
1.55 (1.16 to 2.08)†
NA
1.20 (0.70 to 2.06)
NA
0.39
0.31
0.34
Age (per 10-y increase)
Sex (referent: men)
Race/ethnicity (referent: non-Hispanic white)
Methods of blood pressure control, %
Take drug (referent: no)
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Total cholesterol (per 10 mg/dL increase)
Smoking (referent: never)
Menopause (referent: no)
R2
The odds ratios in the 3 multiple logistic regression models were also adjusted for education (more than high school, high school diploma, or less
than high school), health insurance (yes or no), waist circumference (cm), HDL (mg/dL), and HbA1c level (%), all of which were not significant. NA
indicates not applicable.
*P⬍0.05, †P⬍0.01, and ‡P⬍0.001 after adjusting for the remaining factors.
physiological role in very elderly women.23 The nonsignificant difference in blood pressure control rate between premenopausal and postmenopausal women in our analysis
could also be because of the limited sample size, because
⬎82% of the women with diagnosed hypertension were
postmenopausal.
Because aging is a risk factor for hypertension, it is
expected that increasing age would be associated with uncontrolled blood pressure. In the Framingham Study, the incidence of cardiovascular diseases in women increased with
age and became higher than that in men after menopause.24
Both chronological and ovarian age may play a role in the
increases in waist circumference and fat mass and the
decrease in skeletal muscle mass in women at midlife.25 This
change in body composition may explain the association of
increasing age with uncontrolled blood pressure in women.
Our study also highlighted the high prevalence of central
obesity in people with hypertension, especially in women
(⬎79%). Obesity is a well-known risk factor for hypertension.21 The association of weight control with uncontrolled
blood pressure in women could be explained by the fact that
most of the people practicing weight control are obese and,
therefore, have poorer control.
Given the greater prevalence of cardiovascular risk
factors in women, it is encouraging that more women had
their blood pressure reading checked by doctors within the
past 6 months, which was significantly associated with
good blood pressure control. Improved detection of hypertension in women can also lead to better detection of other
cardiovascular risk factors, which may explain the greater
improvement in concomitant cardiovascular risk factors
than men in the period 1999 –2004. We found an alarming
increase in the prevalence of diabetes among women with
hypertension. This may be because of increased detection
rate, because the mean HbA1c did not change significantly
with time. Blood pressure control is extremely important in
people with diabetes, because hypertensive people with
diabetes have ⬎2-fold risks of cardiovascular morbidity
and mortality.26 We found that diabetes was associated
with uncontrolled blood pressure. This might be because of
obesity, a more stringent blood pressure target in people
with diabetes, or renal involvement.
The higher rate of uncontrolled blood pressure and prevalence of other cardiovascular risk factors in non-Hispanic
black Americans could be because of genetic, cultural, and
social factors, including insurance, access to care, and medications.27,28 It is interesting that current smoking was associated with better blood pressure control, especially in men.
Smoking is recognized to be associated with weight loss, and
weight gain often occurs after smoking cessation.29 It has
been reported in epidemiologic studies that smokers had
lower blood pressure than nonsmokers, and cessation of
smoking results in higher blood pressure and risk of hypertension.30,31 The reason for this paradox is uncertain. A
6
Hypertension
April 2008
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previous report on an elderly community-based population in
Norway shows a positive correlation of nonsmoking or
smoking cessation with a greater use of blood pressure- and
cholesterol-lowering drugs, probably because of higher
awareness of health status among smokers.32
We have previously reported improved blood pressure
control rates among all of the hypertensive persons in
NHANES and among all of those on treatment for hypertension.9 Although there were significant decreases in systolic
and diastolic blood pressures in the present study, the decrease in the proportion with uncontrolled blood pressure did
not reach statistical significance. This might be because of the
inclusion of individuals diagnosed to have hypertension who
were not on drug treatment.
This study made use of the NHANES database with its
large sample sizes that can provide nationally representative
estimates, good sampling design, and quality control. Subjects with undiagnosed hypertension were excluded from this
study, because these subjects were not aware of their hypertension and might, therefore, not have taken any actions to
control blood pressure and related cardiovascular risks. However, there were also several limitations in this study. The
prevalence of diabetes reported did not include undiagnosed
persons. Our definition of hypertension excluded hypertensive subjects with blood pressure successfully controlled by
nonpharmacological means. There may be unrecognized
variables causing residual confounding that explains the
observed gender differences. Duration of hypertension and
treatment may account for some of the gender differences,
but this information was not available in the database.
Also, the cross-sectional survey design makes it difficult to
analyze trends over time, which may simply reflect population trends in how hypertension is diagnosed, as well
as the different lifestyle and pharmacological treatments
available.
Perspectives
Our study indicated that there was no significant difference in
blood pressure control between men and women in the period
1999 –2004. The prevalence of central obesity, elevated total
cholesterol, low HDL, and the mean number of cardiovascular risk factors were higher in women. Women have more risk
factors than men, which may be because of their higher
prevalence of central obesity. Although there is still room for
improvement in blood pressure control, our study has highlighted the importance of addressing other concomitant cardiovascular risk factors in women, especially those related to
central obesity.
Disclosures
None.
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Gender Difference in Blood Pressure Control and Cardiovascular Risk Factors in
Americans With Diagnosed Hypertension
Kwok Leung Ong, Annette W.K. Tso, Karen S.L. Lam and Bernard M.Y. Cheung
Downloaded from http://hyper.ahajournals.org/ by guest on June 14, 2017
Hypertension. published online February 7, 2008;
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