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West African Ancestry and Nocturnal Blood Pressure in African Americans: The Jackson Heart Study.

ABSTRACT: BACKGROUND:African Americans have a higher prevalence of nocturnal hypertension and nondipping blood pressure than European Americans, but the genetic contribution to these racial differences remains unclear. We assessed the association of the percentage West African genetic ancestry with nocturnal hypertension and nondipping blood pressure in 932 African Americans from the Jackson Heart Study. METHODS:Using percentage West African ancestry determined from 389 ancestry informative markers, participants were categorized into tertiles (tertile 1 [low]: <79.3%, tertile 2: ?79.3-86.3%, and tertile 3 [high]: >86.3%). Nocturnal hypertension was defined as mean nighttime (midnight-6 am) systolic (SBP)/diastolic blood pressure ?120/70 mm Hg. Nondipping blood pressure was defined as mean nighttime-to-daytime (10 am-8 pm) SBP ratio >0.90. RESULTS:Nocturnal hypertension was present in 57.9% of participants; 66.6% had nondipping blood pressure. The mean age was 59.4 years, 32.8% were male, and 56.0% were taking antihypertensive medication. The prevalence ratios (95% confidence interval) adjusted for age, sex, cardiovascular disease risk factors, and socioeconomic and psychosocial factors comparing participants with moderate and high to those with low percentage West African ancestry for nocturnal hypertension were 0.98 (0.87-1.10) and 0.95 (0.84-1.08), respectively, and for nondipping blood pressure was 0.96 (0.86-1.07) and 0.98 (0.88-1.09), respectively. CONCLUSIONS:West African ancestry was not associated with nocturnal hypertension and nondipping blood pressure among African Americans. While rare genetic variants cannot be ruled out, these data highlight the need to better understand how environmental and behavioral factors contribute to differences in nocturnal blood pressure among African Americans compared with European Americans.

SUBMITTER: Booth JN

PROVIDER: S-EPMC5946866 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature

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West African Ancestry and Nocturnal Blood Pressure in African Americans: The Jackson Heart Study.

Booth John N JN Li Man M Shimbo Daichi D Hess Rachel R Irvin Marguerite R MR Kittles Rick R Wilson James G JG Jorde Lynn B LB Cheung Alfred K AK Lange Leslie A LA Lange Ethan M EM Yano Yuichiro Y Muntner Paul P Bress Adam P AP

American journal of hypertension 20180501 6

<h4>Background</h4>African Americans have a higher prevalence of nocturnal hypertension and nondipping blood pressure than European Americans, but the genetic contribution to these racial differences remains unclear. We assessed the association of the percentage West African genetic ancestry with nocturnal hypertension and nondipping blood pressure in 932 African Americans from the Jackson Heart Study.<h4>Methods</h4>Using percentage West African ancestry determined from 389 ancestry informative ...[more]

PMID: 29528363

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Project description:BackgroundAmbulatory blood pressure (BP) monitoring is the reference standard for out-of-clinic BP measurement. Thresholds for identifying ambulatory hypertension (daytime systolic BP [SBP]/diastolic BP [DBP] ≥135/85 mm Hg, 24-hour SBP/DBP ≥130/80 mm Hg, and nighttime SBP/DBP ≥120/70 mm Hg) have been derived from European, Asian, and South American populations. We determined BP thresholds for ambulatory hypertension in a US population-based sample of African American adults.MethodsWe analyzed data from the Jackson Heart Study, a population-based cohort study comprised exclusively of African American adults (n=5306). Analyses were restricted to 1016 participants who completed ambulatory BP monitoring at baseline in 2000 to 2004. Mean SBP and DBP levels were calculated for daytime (10:00 am-8:00 pm), 24-hour (all available readings), and nighttime (midnight-6:00 am) periods, separately. Daytime, 24-hour, and nighttime BP thresholds for ambulatory hypertension were identified using regression- and outcome-derived approaches. The composite of a cardiovascular disease or an all-cause mortality event was used in the outcome-derived approach. For this latter approach, BP thresholds were identified only for SBP because clinic DBP was not associated with the outcome. Analyses were stratified by antihypertensive medication use.ResultsAmong participants not taking antihypertensive medication, the regression-derived thresholds for daytime, 24-hour, and nighttime SBP/DBP corresponding to clinic SBP/DBP of 140/90 mm Hg were 134/85 mm Hg, 130/81 mm Hg, and 123/73 mm Hg, respectively. The outcome-derived thresholds for daytime, 24-hour, and nighttime SBP corresponding to a clinic SBP ≥140 mm Hg were 138 mm Hg, 134 mm Hg, and 129 mm Hg, respectively. Among participants taking antihypertensive medication, the regression-derived thresholds for daytime, 24-hour, and nighttime SBP/DBP corresponding to clinic SBP/DBP of 140/90 mm Hg were 135/85 mm Hg, 133/82 mm Hg, and 128/76 mm Hg, respectively. The corresponding outcome-derived thresholds for daytime, 24-hour, and nighttime SBP were 140 mm Hg, 137 mm Hg, and 133 mm Hg, respectively, among those taking antihypertensive medication.ConclusionsOn the basis of the outcome-derived approach for SBP and regression-derived approach for DBP, the following definitions for daytime, 24-hour, and nighttime hypertension corresponding to clinic SBP/DBP ≥140/90 mm Hg are proposed for African American adults: daytime SBP/DBP ≥140/85 mm Hg, 24-hour SBP/DBP ≥135/80 mm Hg, and nighttime SBP/DBP ≥130/75 mm Hg, respectively.

Project description:OBJECTIVE:To determine whether genetic ancestry was associated with subclinical atherosclerosis measures after adjustment for traditional cardiovascular disease risk factors, inflammatory marker, socioeconomic status, and psychosocial factors in a large admixed African American population. APPROACH AND RESULTS:Participants were drawn from the Jackson Heart Study. Participant's percent of European ancestry (PEA) was estimated based on 1747 genetic markers using HAPMIX. Association of PEA with peripheral arterial disease and common carotid intima-media thickness were investigated among 2168 participants and with coronary artery calcification >0 and abdominal aortic calcification >0 among 1139 participants. The associations were evaluated using multivariable regression models. Our results showed that a 1 SD increase in PEA was associated with a lower peripheral arterial disease prevalence after adjusting for age and sex (prevalence ratio=0.90 [95% CI, 0.82-0.99]; P=0.036). Adjustments for traditional cardiovascular disease risk factors, socioeconomic status, and psychosocial factors attenuated this association (prevalence ratio=0.91 [0.82-1.00]; P=0.046). There was also a nonlinear association between PEA and coronary artery calcification and abdominal aortic calcification. The lowest PEA was associated with a lower coronary artery calcification (prevalence ratio=0.75 [0.58-0.96]; P=0.022) and a lower abdominal aortic calcification [prevalence ratio=0.80 [0.67-0.96]; P=0.016) compared with the reference group (10th-90th percentile) after adjusting for traditional cardiovascular disease risk factors, inflammatory marker, socioeconomic status, and psychosocial factors. However, we found no significant association between PEA and common carotid intima-media thickness. CONCLUSIONS:Overall, our findings indicate that genetic ancestry was associated with subclinical atherosclerosis, suggesting unmeasured risk factors and interactions with genetic factors might contribute to the distribution of subclinical atherosclerosis among African Americans.

Project description:BackgroundThe renin-angiotensin-aldosterone system (RAAS) is an important driver of blood pressure (BP), but the association of the RAAS with ambulatory BP (ABP) and ABP monitoring phenotypes among African Americans has not been assessed.MethodsABP and ABP monitoring phenotypes were assessed in 912 Jackson Heart Study participants with aldosterone and plasma renin activity (PRA). Multivariable linear and logistic regression analyses were used to analyze the association of aldosterone and PRA with clinic, awake, and asleep systolic BP and diastolic BP (DBP) and ABP monitoring phenotypes, adjusting for important confounders.ResultsThe mean age of participants was 59±11 years and 69% were female. In fully adjusted models, lower log-PRA was associated with higher clinic, awake, and asleep systolic BP and DBP (all P<0.05). A higher log-aldosterone was associated with higher clinic, awake, and asleep DBP (all P<0.05). A 1-unit higher log-PRA was associated with lower odds of daytime hypertension (odds ratio [OR] 0.59 [95% CI, 0.49-0.71]), nocturnal hypertension (OR, 0.68 [95% CI, 0.58-0.79]), daytime and nocturnal hypertension (OR, 0.59 [95% CI, 0.48-0.71]), sustained hypertension (OR, 0.52 [95% CI, 0.39-0.70]), and masked hypertension (OR 0.75 [95% CI, 0.62-0.90]). A 1-unit higher log-aldosterone was associated with higher odds of nocturnal hypertension (OR, 1.38 [95% CI, 1.05-1.81]). Neither PRA nor aldosterone was associated with percent dipping, nondipping BP pattern, or white-coat hypertension. Patterns for aldosterone:renin ratio were similar to patterns for PRA.ConclusionsSuppressed renin activity and higher aldosterone:renin ratios were associated with higher systolic BP and DBP in the office and during the awake and asleep periods as evidenced by ABP monitoring. Higher aldosterone levels were associated with higher DBP, but not systolic BP, in the clinic and during the awake and asleep periods. Further clinical investigation of novel and approved medications that target low renin physiology such as epithelial sodium channel inhibitors and mineralocorticoid receptor antagonists may be paramount in improving hypertension control in African Americans.

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West African Ancestry and Nocturnal Blood Pressure in African Americans: The Jackson Heart Study.

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West African Ancestry and Nocturnal Blood Pressure in African Americans: The Jackson Heart Study.

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