Determinants of day-night difference in blood pressure, a comparison with determinants of daytime and night-time blood pressure.
ABSTRACT: Blunted day-night difference in blood pressure (BP) is an independent cardiovascular risk factor, although there is limited information on determinants of diurnal variation in BP. We investigated determinants of day-night difference in systolic (SBP) and diastolic (DBP) BP and how these compared with determinants of daytime and night-time SBP and DBP. We analysed the association of mean daytime, mean night-time and mean day-night difference (defined as (mean daytime-mean night-time)/mean daytime) in SBP and DBP with clinical, lifestyle and biochemical parameters from 1562 adult individuals (mean age 38.6) from 509 nuclear families recruited in the GRAPHIC Study. We estimated the heritability of the various BP phenotypes. In multivariate analysis, there were significant associations of age, sex, markers of adiposity (body mass index and waist-hip ratio), plasma lipids (total and low-density lipoprotein cholesterol and triglycerides), serum uric acid, alcohol intake and current smoking status on daytime or night-time SBP and/or DBP. Of these, only age (P=4.7 × 10-5), total cholesterol (P=0.002), plasma triglycerides (P=0.006) and current smoking (P=3.8 × 10-9) associated with day-night difference in SBP, and age (P=0.001), plasma triglyceride (P=2.2 × 10-5) and current smoking (3.8 × 10-4) associated with day-night difference in DBP. 24-h, daytime and night-time SBP and DBP showed substantial heritability (ranging from 18-43%). In contrast day-night difference in SBP showed a lower heritability (13%) while heritability of day-night difference in DBP was not significant. These data suggest that specific clinical, lifestyle and biochemical factors contribute to inter-individual variation in daytime, night-time and day-night differences in SBP and DBP. Variation in day-night differences in BP is largely non-genetic.
Project description:OBJECTIVE:A systematic review on the reproducibility of ambulatory blood pressure measurements (ABPM) has not yet been conducted. This meta-analysis compared 24-h/daytime/night-time SBP and DBP mean values and SBP/DBP nocturnal dipping status from ABPMs in participants with or without hypertension. METHODS:Ovid MEDLINE, EMBASE, and CINAHL Complete databases were searched for articles published before 3 May 2019. Eligible studies reporting a 24-h ABPM repeated at least once within 1 month were included. The mean daytime/night-time/24-h BP values, percentage of nocturnal dipping, and proportion of nondippers were compared between the first and second day of measurements, and the proportion of participants with inconsistent dipping status were estimated using a random effect model. RESULTS:Population-based analysis found a 0-1.1 mmHg difference between the first and second ABPM for 24-h/daytime/night-time SBP and DBP and 0-0.5% for percentage of SBP/DBP nocturnal dipping. The proportion of non-dippers was not different between the first and second ABPM. Intra-individual analysis found that the 95% limit of agreements (LOA) for SBP/DBP were wide and the 95% LOA for daytime SBP, common reference to diagnose hypertension, ranged -16.7 to 18.4 mmHg. Similarly, 32% of participants had inconsistent nocturnal dipping status. CONCLUSION:ABPM had excellent reproducibility at the population level, favouring its application for research purposes; but reproducibility of intra-individual BP values and dipping status from a 24-h ABPM was limited. The available evidence was limited by the lack of high-quality studies and lack of studies in non-Western populations.
Project description:Nighttime blood pressure (BP) has been shown to be superior to daytime BP in predicting hypertension related target organ damage and cardiac mortality. In our Georgia Cardiovascular Twin Study, we showed that apart from the genes that also influence daytime BP, specific genetic determinants explained 44% and 67% of the nighttime systolic BP (SBP) and diastolic BP (DBP) heritabilities, respectively. Here, we determined whether these results could be confirmed in a much larger twin cohort of young adults with 24-hour ambulatory BP measurements.Ambulatory BP was available in 703 white twins (308 pairs and 87 singletons, aged 18-34 years, 50% males) from the Prenatal Programming Twin Study. A bivariate quantitative genetic twin model was used to analyze daytime and nighttime BP. We conducted a meta-analysis to compare and integrate results from the 2 twin cohorts.Model fitting showed no sex differences for any of the measures. Heritabilities were 0.60 and 0.51 for SBP and 0.54 and 0.46 for DBP at daytime and nighttime. The specific heritability due to novel genetic effects emerging during the nighttime was 0.21 for SBP and 0.26 for DBP, which comprised 41% and 57% of the total nighttime heritability for SBP and DBP, respectively. Meta-analysis confirmed absence of cohort differences with very similar combined results.In addition to genes that influence both daytime and nighttime BP, a large part of the heritability is explained by genes that specifically influence BP at night.
Project description:The present study evaluated the response of blood pressure (BP) by dietary sodium in sodium resistant (SR) subjects. One hundred one subjects (mean age, 46.0 yr; 31 hypertensives) were admitted and given low sodium-dietary approaches to stop hypertension (DASH) diet (LSD, 100 mM NaCl/day) for 7 days and high sodium-DASH diet (HSD, 300 mM NaCl/day) for the following 7 days. On the last day of each diet, 24 hr ambulatory BP was measured. Morning systolic BP (SBP) and diastolic BP (DBP) were elevated after HSD in all subjects (P < 0.01), but daytime SBP and DBP were not changed (P > 0.05). In hypertensive subjects, morning DBP elevation was greater than daytime DBP elevation (P = 0.036), although both DBPs were significantly elevated after HSD. The augmented elevation of morning DBP in hypertensive subjects was contributed by the absolute elevation of morning DBP (P = 0.032) and relative elevation to daytime DBP (P = 0.005) in sodium resistant (SR) subjects, but not by sodium sensitive subjects. Although there was no absolute elevation, SR subjects with normotension showed a relative elevation of morning SBP compared to daytime SBP change after HSD (P = 0.009). The present study demonstrates an absolute and relative elevation of morning BP in SR subjects by HSD.
Project description:Insulin resistance has been related to elevated blood pressure (BP) in obese children and may adversely affect the vasculature by arterial stiffening. The objective was to investigate whether daytime and nighttime BP were elevated and related to insulin resistance and arterial stiffness in obese children and adolescents.Ninety-two obese patients aged 10-18 years were compared with 49 healthy control individuals. Insulin resistance was measured as the homeostatic assessment model (HOMA), and arterial stiffness was measured as carotid-femoral pulse wave velocity (cfPWV).Mean ± SD daytime systolic BP (SBP) (obese: 125±8.3mm Hg; control: 121±10.1mm Hg; P = 0.03) and nighttime SBP (obese: 108±10.7mm Hg; control: 102±8.2mm Hg; P = 0.0001) were higher in the obese group when compared with the control group. No difference was found in daytime diastolic BP (DBP), whereas nighttime DBP (obese: 60±6.6mm Hg; control: 57±4.8mm Hg; P = 0.001) and night-to-day BP ratios were higher in the obese group. Nighttime SBP was related to BMI z score (β = 6.0; 95% confidence interval (CI) = 2.9-9.1; P = 0.0002) and waist/height ratio (β = 36.7; 95% CI = 5.6-67.9; P = 0.02) in the obese group. HOMA index (obese: median = 3.7, interquartile range (IQR) = 2.3-6.0; control: median = 2.6, IQR = 1.8-3.4; P = 0.002) was higher, whereas cfPWV (obese: 4.8±0.8 m/s; control: 5.1±0.6 m/s; P = 0.03) was lower in the obese group. CfPWV was not related to logHOMA index. In multiple regression analyses, the higher nighttime BP in the obese group was independent of logHOMA and cfPWV.Obese children had a higher nighttime BP when compared with the control group independently of insulin resistance and arterial stiffness. No relationship was found between insulin resistance and arterial stiffness. CLINICAL TRIAL REGISTRATION Clinicaltrials.gov identifier NCT01310088.
Project description:OBJECTIVE:The objective of this study was to validate the accuracy of beat-to-beat measurements with those taken with an aneroid sphygmomanometer by auscultatory method. A secondary aim was to explore differences between auscultatory and beat-to-beat blood pressure (BP) with daytime ambulatory BP measurements. PARTICIPANTS AND METHODS:A total of 46 participants, comprising 21 males, aged 47±13 years, height 171±8.5 cm and weight 82±16.8 kg attended the Exercise Physiology Laboratory at the University of New England (Armidale, New South Wales, Australia). During the visit, participants had their BP - systolic BP (SBP) and diastolic BP (DBP) - measured using auscultatory methods and a Finometer. An ambulatory BP monitor was fitted during the same visit and worn for a minimum of 12 h. RESULTS:Auscultatory measurements were slightly higher than beat-to-beat for both SBP and DBP. There was no difference between auscultatory and beat-to-beat SBP with a mean difference of 0.23 mmHg (P=0.87). There were disparities between auscultatory and beat-to-beat DBP, with a mean difference of 4.82 mmHg (P<0.01). Daytime ambulatory BP was higher than both auscultatory and beat-to-beat measurements for both SBP and DBP, with P less than 0.001 for all measures. CONCLUSION:There was a high level of reliability in the beat-to-beat SBP with that seen by auscultatory; however, there were disparities in DBP measurements using the same devices, which raise concerns over the accuracy of beat-to-beat DBP. Ambulatory systolic and diastolic measures were higher than beat-to-beat and auscultatory; however, they may be more suitable for monitoring diurnal changes in BP, depending upon the research model.
Project description:BACKGROUND:Ambulatory 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. METHODS:We 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. RESULTS:Among 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. CONCLUSIONS:On 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:To determine the effectiveness and safety of once-daily combination therapy with amlodipine, valsartan and hydrochlorothiazide for reducing ambulatory blood pressure (ABP) in patients with moderate to severe hypertension, a multicenter, double-blind study was performed (N=2271) that included ABP monitoring in a 283-patient subset. After a single-blind, placebo run-in period, patients were randomized to receive amlodipine/valsartan/hydrochlorothiazide (10/320/25?mg), valsartan/hydrochlorothiazide (320/25?mg), amlodipine/valsartan (10/320?mg) or amlodipine/hydrochlorothiazide (10/25?mg) each morning for 8 weeks. Efficacy assessments included change from baseline in 24-h, daytime and night time mean ambulatory systolic BP (SBP) and diastolic BP (DBP). Statistically significant and clinically relevant reductions from baseline in all these parameters occurred in all treatment groups (P<0.0001, all comparisons versus baseline). At week 8, least squares mean reductions from baseline in 24-h, daytime and night time mean ambulatory SBP/DBP were 30.3/19.7, 31.2/20.5 and 28.0/17.8?mm?Hg, respectively, with amlodipine/valsartan/hydrochlorothiazide; corresponding reductions with dual therapies ranged from 18.8-24.1/11.7-15.5, 19.0-25.1/12.0-16.0 and 18.3-22.6/11.1-14.3?mm?Hg (P?0.01, all comparisons of triple versus dual therapy). Treatment with amlodipine/valsartan/hydrochlorothiazide maintained full 24-h effectiveness, including during the morning hours; all hourly mean ambulatory SBP and mean ambulatory DBP measurements were ?130/85?mm?Hg at end point. Amlodipine/valsartan/hydrochlorothiazide combination therapy was well tolerated. Once-daily treatment with amlodipine/valsartan/hydrochlorothiazide (10/320/25?mg) reduces ABP to a significantly greater extent than component-based dual therapy and maintains its effectiveness over the entire 24-h dosing period.
Project description:Importance:Little is known regarding health outcomes associated with higher blood pressure (BP) levels measured outside the clinic among African American individuals. Objective:To examine whether daytime and nighttime BP levels measured outside the clinic among African American individuals are associated with cardiovascular disease (CVD) and all-cause mortality independent of BP levels measured inside the clinic. Design, Setting, and Participants:This prospective cohort study analyzed data from 1034 African American participants in the Jackson Heart Study who completed ambulatory BP monitoring at baseline (September 26, 2000, to March 31, 2004). Mean daytime and nighttime BPs were calculated based on measurements taken while participants were awake and asleep, respectively. Data were analyzed from July 1, 2017, to April 30, 2019. Main Outcomes and Measures:Cardiovascular disease events, including coronary heart disease and stroke, experienced through December 31, 2014, and all-cause mortality experienced through December 31, 2016, were adjudicated. The associations of daytime BP and nighttime BP, separately, with CVD events and all-cause mortality were determined using Cox proportional hazards regression models. Results:A total of 1034 participants (mean [SD] age, 58.9 [10.9] years; 337 [32.6%] male; and 583 [56.4%] taking antihypertensive medication) were included in the study. The mean daytime systolic BP (SBP)/diastolic BP (DBP) was 129.4/77.6 mm Hg, and the mean nighttime SBP/DBP was 121.3/68.4 mm Hg. During follow-up (median [interquartile range], 12.5 [11.1-13.6] years for CVD and 14.8 [13.7-15.6] years for all-cause mortality), 113 CVD events and 194 deaths occurred. After multivariable adjustment, including in-clinic SBP and DBP, the hazard ratios (HRs) for CVD events for each SD higher level were 1.53 (95% CI, 1.24-1.88) for daytime SBP (per 13.5 mm Hg), 1.48 (95% CI, 1.22-1.80) for nighttime SBP (per 15.5 mm Hg), 1.25 (95% CI, 1.02-1.51) for daytime DBP (per 9.3 mm Hg), and 1.30 (95% CI, 1.06-1.59) for nighttime DBP (per 9.5 mm Hg). Nighttime SBP was associated with all-cause mortality (HR per 1-SD higher level, 1.24; 95% CI, 1.06-1.45), but no association was present for daytime SBP (HR, 1.13; 95% CI, 0.97-1.33) and daytime (HR, 0.95; 95% CI, 0.81-1.10) and nighttime (HR, 1.06; 95% CI, 0.90-1.24) DBP. Conclusions and Relevance:Among African American individuals, higher daytime and nighttime SBPs were associated with an increased risk for CVD events and all-cause mortality independent of BP levels measured in the clinic. Measurement of daytime and nighttime BP using ambulatory monitoring during a 24-hour period may help identify African American individuals who have an increased cardiovascular disease risk.
Project description:INTRODUCTION:Nocturnal hypertension is clinically important for patients with type 2 diabetes (T2D), considering its strong correlation with cardiovascular events. We aim to test the hypothesis that the sodium-glucose cotransporter 2 inhibitor, luseogliflozin, ameliorates nocturnal hypertension more effectively than a dipeptidyl peptidase (DPP)-4 inhibitor in patients with T2D. METHODS AND ANALYSIS:This study is a multicentre, prospective, randomised, open-label, blinded endpoint parallel-group trial. Sixty participants with T2D and hypertension who have been treated with a DPP-4 inhibitor for more than 4 weeks and who have a glycated haemoglobin A1c (HbA1c) level of 6.0%-9.0% will be randomised based on age, body mass index (BMI) and HbA1c to continue taking their DPP-4 inhibitor or to switch to luseogliflozin 2.5?mg once daily for 8 weeks. Twenty-four-hour ambulatory blood pressure monitoring (ABPM) will be performed twice at baseline and at the end of the study. All participants will continue their diet and exercise therapy, and the doses of concomitant medications will not be adjusted during the study. The primary endpoint is the effect of luseogliflozin on the mean change in systolic blood pressure (SBP) during the night, as measured by ABPM. The secondary endpoints are mean change in diastolic blood pressure (DBP) during the night, 24 hours of SBP and DBP, daytime SBP and DBP, pulse rate, BP M-value, trough SBP and DBP for 1?hour before the next dose, and other laboratory parameters. The sample size was calculated for a two-sided test at 90% power for the detection of a difference between treatments. ETHICS AND DISSEMINATION:The Ethics Review Board of Hokkaido University Hospital has approved the protocol. The results will be disseminated in peer-reviewed journals and at scientific conferences. TRIAL REGISTRATION NUMBERS:The University Hospital Medical Information Network (UMIN000031451); Japan Registry of Clinical Trials (jRCTs011180019); Pre-results.
Project description:OBJECTIVE:To more precisely and comprehensively estimate the genetic and environmental correlations between various indices of obesity and BP. METHODS:We estimated heritability and genetic correlations of obesity indices with BP in the Oman family study (n?=?1231). Ambulatory and office beat-to-beat BP was measured and mean values for SBP and DBP during daytime, sleep, 24-h and 10?min at rest were calculated. Different indices were used to quantify obesity and fat distribution: BMI, percentage of body fat (%BF), waist circumference and waist-to-height ratio (WHtR). SOLAR software was used to perform univariate and bivariate quantitative genetic analyses adjusting for age, age, sex, age-sex and age--sex interactions. RESULTS:Heritabilities of BP ranged from 30.2 to 38.2% for ambulatory daytime, 16.8--21.4% for sleeping time, 32.1--40.4% for 24-h and 22--24.4% for office beat-to-beat measurements. Heritabilities for obesity indices were 67.8% for BMI, 52.2% for %BF, 37.3% for waist circumference and 37.9% for WHtR. All obesity measures had consistently positive phenotypic correlations with ambulatory and office beat-to-beat SBP and DBP (r-range: 0.14--0.32). Genetic correlations of obesity indices with SBP and DBP were higher than environmental correlations (rG: 0.16--0.50; rE: 0.01--0.31). CONCLUSION:The considerable genetic overlap between a variety of obesity indices and both ambulatory and office beat-to-beat BP highlights the relevance of pleiotropic genes. Future GWAS analyses should discover the specific genes both influencing obesity indices and BP to help unravel their shared genetic background.