Title: Nocturnal Blood Pressure Dipping, Acculturation, and the Metabolic Syndrome in Hispanic Women
1Nocturnal Blood Pressure Dipping, Acculturation,
and the Metabolic Syndrome in Hispanic Women
- Smriti Shivpuri, M.S.
- Linda C. Gallo, Ph.D.
- San Diego State University/
- University of California San Diego
- Joint Doctoral Program in Clinical Psychology
2Nocturnal Blood Pressure (NBP) Dipping
- NBP dipping defined as difference between diurnal
and nocturnal levels of BP - Typical NBP dipping in adults 10-20
- Classification
- Non-dippers lt10
- Dippers gt/ 10
- Extreme Dippers gt20
- Reverse Dippers higher nocturnal BP
3NBP Dipping and Cardiovascular Disease (CVD)
Outcomes
- Non-dipping linked to increased risk of a variety
of CVD outcomes - Heart failure, Myocardial Infarction1
- Stroke2
- Sudden Death1
- Target Organ damage3
- Carotid IMT4
- Left ventricular hypertrophy5
- Mediating physiological mechanisms poorly
understood
4Metabolic Syndrome (MetSyn)
- Syndrome characterized by constellation of risk
factors of metabolic origin - Defined by NCEP ATPIIIa as 3 of following
(women)
aNational Cholesterol Education Program Adult
Treatment Panel III
5Metabolic Syndrome
- MetSyn may be mediating mechanism between NBP
dipping and CVD - Associated with almost three-fold increased risk
of CVD6 - Research addressing association between NBP
dipping and the MetSyn is limited - Linked to NBP Dipping in some studies
- Greater prevalence of MetSyn in non-dippers
versus dippers7,8, 9 - Higher mean score of MetSyn (when measured
continuously) in non-dippers than dippers10 - No association in other studies11
6NBP Dipping in Hispanics
- Evidence exists that NBP Dipping differs by race
- African-Americans more likely to have blunted
NBP Dipping than non-Hispanic Whites, and be
classified as non-dippers12,13 - Little to no work to date on NBP Dipping and CVD
outcomes in Hispanics - Some evidence that Hispanic men may be more
likely to be non-dippers than non-Hispanic
Whites, but not true for Hispanic women14 - One study found greater odds of stroke in
nondippers versus dippers for African-Americans
and non-Hispanic Whites, but not in Caribbean
Hispanics15
7NBP Dipping and MetSyn in Hispanics
- Among ethnic minority groups in U.S.,
Mexican-Americans have one of highest rates of
MetSyn16 - No studies have looked at link between NBP
Dipping and MetSyn in Hispanics or non-diseased
populations, or examined whether acculturation,
which has been shown to affect the relationship
between risk factors and CVD outcomes, moderates
relationship
Note. Image courtesy http//img.medscape.com/slid
e/migrated/editorial/cmecircle/2006/5186/images/ca
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8Current Study
- Purpose To examine relationship between NBP
dipping and MetSyn in Mexican-American women and
explore whether association is modified by
acculturation level - Sample 277 middle-aged (M49.56yrs) healthy
Mexican-American women, recruited from South San
Diego border community - Inclusion criteria age between 40-65 years,
Mexican-American ethnicity, literate in English
or Spanish, and free of major health conditions
(e.g., CVD, cancer) and medications with
autonomic effects - Methods Completed battery of questionnaires
assessing sociodemographic, health
history/behavior, and psychosocial factors, and
next day underwent assessment of MetSyn
components and completed 36hr ambulatory BP
(AmBP) protocol
9Assessment
- NBP Dipping
- AmBP monitor recorded participants BP every half
hour during day, every hour during night - Resulted in an average of 60 BP readings per
person over 36 hours - Calculated as (average diurnal BP - average
NBP)/ average diurnal BP100 - Acculturation
- Measured using preferred language version of
survey (commonly used proxy) - Low Acculturated (Spanish) 0 High Acculturated
(English) 1 - MetSyn (defined using NCEP ATP III criteria)
- Waist circumference, height, weight measured by
trained assessors - Average SBP, DBP recorded as mean of 3
measurements while seated - Glucose, HDL, triglycerides obtained through
fasting blood draw
10Analyses
- Hierarchical Linear Modeling (HLM) used to obtain
average diurnal and nocturnal BP levels across
repeated measurements while accounting for
nesting of measurements within individuals - Logistic Regression used to test effects of NBP
dipping (SBP and DBP), acculturation, and their
interaction on probability of MetSyn - Covariates (identified from prior research)
included - Average daytime BP
- Age
- Body Mass Index
- Socioeconomic status (measured by educational
attainment)
11Results
- No significant association between Diastolic BP
dipping or Diastolic NBP dippingAcculturation
interaction and MetSyn - Significant Systolic NBP (NSBP)
dippingAcculturation interaction
12Results
- Decreased NSBP dipping associated with increased
risk for MetSyn (i.e., increased NSBP dipping
protective), but only for high acculturated women
Association between Gradations of Systolic NBP
(NSBP) Dipping and Odds of MetSyn in High
Acculturated women
Odds Ratios
p lt .05 plt.10
13Conclusions
- Systolic NBP dipping associated with MetSyn in
high-acculturated but not low-acculturated
Mexican-American women - Each 10 decrease in dipping associated with 3.67
increased odds of MetSyn - Trend for non-dippers having three fold greater
odds of MetSyn as compared to dippers (p.06) - Diastolic NBP dipping not associated with MetSyn
- Finding suggests mechanisms by which NBP dipping
relate to MetSyn may differ by acculturation - Less acculturated, more traditional women may be
buffered against harmful metabolic effects of
increased blood pressure load
14Potential Buffering Mechanisms
- Sociodemographic Factors
- Marital Status, Income
- Psychosocial Factors
- Social support, Anger, Hostility, Chronic Stress,
Racism - Behavioral Factors
- Smoking, alcohol consumption, physical activity
- Addition of these factors in exploratory
follow-up analyses attenuated interaction effect,
but it remained statistically significant - Interestingly, for high-acculturated women NSBP
dipping associated with DBP, waist circumference
and HDL components of MetSyn for
low-acculturated, only waist circumference
15Limitations/Future Directions
- Limitations
- Cross-sectional study
- Ambulatory BP measurement for dipping only 36
hour cycle - No gender or ethnic comparisons possible
- Future directions
- Explore whether NBP dipping association with CVD
outcomes varies by acculturation status in
Hispanics - Determine whether NBP dipping is related to
other, non-metabolic factors in low-acculturated
Hispanics (e.g., serum uric acid levels,
hyperthyroidism, hyperaldosteronism)17 - Cross-gender and cross-ethnic comparisons with
Hispanics on association between NBP dipping and
CVD outcomes
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