Single Blood Pressure Measurement Research Articles

Long-Term Exposure to Elevated Systolic Blood Pressure in Predicting Incident Cardiovascular Disease: Evidence From Large-Scale Routine Electronic Health Records.

BackgroundHow measures of long‐term exposure to elevated blood pressure might add to the performance of “current” blood pressure in predicting future cardiovascular disease is unclear. We compared incident cardiovascular disease risk prediction using past, current, and usual systolic blood pressure alone or in combination.Methods and ResultsUsing data from UK primary care linked electronic health records, we applied a landmark cohort study design and identified 80 964 people, aged 50 years (derivation cohort=64 772; validation cohort=16 192), who, at study entry, had recorded blood pressure, no prior cardiovascular disease, and no previous antihypertensive or lipid‐lowering prescriptions. We used systolic blood pressure recorded up to 10 years before baseline to estimate past systolic blood pressure (mean, time‐weighted mean, and variability) and usual systolic blood pressure (correcting current values for past time‐dependent blood pressure fluctuations) and examined their prospective relation with incident cardiovascular disease (first hospitalization for or death from coronary heart disease or stroke/transient ischemic attack). We used Cox regression to estimate hazard ratios and applied Bayesian analysis within a machine learning framework in model development and validation. Predictive performance of models was assessed using discrimination (area under the receiver operating characteristic curve) and calibration metrics. We found that elevated past, current, and usual systolic blood pressure values were separately and independently associated with increased incident cardiovascular disease risk. When used alone, the hazard ratio (95% credible interval) per 20–mm Hg increase in current systolic blood pressure was 1.22 (1.18–1.30), but associations were stronger for past systolic blood pressure (mean and time‐weighted mean) and usual systolic blood pressure (hazard ratio ranging from 1.39–1.45). The area under the receiver operating characteristic curve for a model that included current systolic blood pressure, sex, smoking, deprivation, diabetes mellitus, and lipid profile was 0.747 (95% credible interval, 0.722–0.811). The addition of past systolic blood pressure mean, time‐weighted mean, or variability to this model increased the area under the receiver operating characteristic curve (95% credible interval) to 0.750 (0.727–0.811), 0.750 (0.726–0.811), and 0.748 (0.723–0.811), respectively, with all models showing good calibration. Similar small improvements in area under the receiver operating characteristic curve were observed when testing models on the validation cohort, in sex‐stratified analyses, or by using different landmark ages (40 or 60 years).ConclusionsUsing multiple blood pressure recordings from patients’ electronic health records showed stronger associations with incident cardiovascular disease than a single blood pressure measurement, but their addition to multivariate risk prediction models had negligible effects on model performance.

Impact of repeated blood pressure measurement on blood pressure categorization in a population-based study from India.

Often a single blood pressure (BP) measurement is used to diagnose and manage hypertension in busy clinics. However, repeated BP measurements have been shown to be more representative of the true BP status of the individual. Improper measurement of office BP can lead to inaccurate classification, overestimation of a patient's true BP, unnecessary treatment, and misinterpretation of the true prevalence of hypertension. There is no consensus among major guidelines on the number of recommended measurements at a single visit or the method of arriving at final clinic BP reading. The participants of the National Family Health Survey (NFHS-4), a nationwide survey conducted in India from 2015 to 2016, were used for the analysis. The prevalence and median difference in systolic blood pressure (SBP) and diastolic blood pressure (DBP) for single as well as combinations of two or more readings were calculated. Cross-tabulation was used to assess classification of individuals based on first BP reading compared with the mean of two or more BP measurements. There was a 63% higher prevalence of hypertension when only the first reading was considered for diagnosis in comparison to the mean of the second and third readings. A decrease of 3.6mmHg and 2.4 mm Hg in mean SBP and DBP, respectively, was observed when the mean of the second and third readings was compared to the first reading. In those who are identified to have grade 1 or higher categories of hypertension, we recommend three BP measurements, with the mean of the second and third measurements being the clinic BP.

The burden of hypertension in the emergency department and linkage to care: A prospective cohort study in Tanzania.

ObjectivesGlobally, hypertension affects one billion people and disproportionately burdens low-and middle-income countries. Despite the high disease burden in sub-Saharan Africa, optimal care models for diagnosing and treating hypertension have not been established. Emergency departments (EDs) are frequently the first biomedical healthcare contact for many people in the region. ED encounters may offer a unique opportunity for identifying high risk patients and linking them to care.MethodsBetween July 2017 and March 2018, we conducted a prospective cohort study among patients presenting to a tertiary care ED in northern Tanzania. We recruited adult patients with a triage blood pressure ≥ 140/90 mmHg in order to screen for hypertension. We explored knowledge, attitudes and practices for hypertension using a questionnaire, and assessed factors associated with successful follow-up. Hypertension was defined as a single blood pressure measurement ≥ 160/100 mmHg or a three-time average of ≥ 140/90 mmHg. Uncontrolled hypertension was defined as a three-time average measurement of ≥ 160/100 mmHg. Successful follow-up was defined as seeing an outpatient provider within one month of the ED visit.ResultsWe enrolled 598 adults (mean age 59.6 years), of whom 539 (90.1%) completed the study. The majority (78.6%) of participants were aware of having hypertension. Many (223; 37.2%) had uncontrolled hypertension. Overall, only 236 (43.8%) of participants successfully followed-up within one month. Successful follow-up was associated with a greater understanding that hypertension requires lifelong treatment (RR 1.11; 95% CI 1.03,1.21) and inversely associated with greater anxiety about the future (RR 0.80; 95% CI 0.64,0.99).ConclusionIn a northern Tanzanian tertiary care ED, the burden of hypertension is high, with few patients receiving optimal outpatient care follow-up. Multi-disciplinary strategies are needed to improve linkage to care for high-risk patients from ED settings.

How to reliably diagnose arterial hypertension: lessons from 24 h blood pressure monitoring

Background: Hypertension is a common condition in modern society. As blood pressure fluctuates with time, a single blood pressure measurement is useless to diagnose hypertension. Nevertheless, no well-defined number of measurements is often used for this purpose. Diagnosis and therapeutic control of hypertension are therefore suboptimal.Objective: To determine the number and timing of measurements needed to give a trustworthy approximation of an individual’s average blood pressure.Methods: In this observational study 306 clinically indicated 24h ABPM datasets were analysed. Hypertension was defined as a daytime blood pressure mean exceeding 135/85 mm Hg. Kappa coefficients determined the best time of day for measuring blood pressure. The optimal number of measurements was estimated using canonical correlation.Results: 162 (53%) patients were diagnosed with hypertension. Kappa statistics indicated that measuring during the afternoon gave the best agreement with the 24h blood pressure mean (κ = 0.78). According to canonical correlation, about 8–10 blood pressure readings give enough information for hypertension diagnosis.Conclusions: Eight to ten blood pressure measurements between 01:00 and 05:00 p.m. are sufficient to give a clinically useful approximation of the daytime mean blood pressure and therefore for diagnosing hypertension accurately. Future research should determine the ideal dispersion of measurements and include patient characteristics which could influence the required number and timing of measurements. These results may increase the future importance of telemonitoring in diagnosing hypertension.

Repeated versus single blood pressure measurement.

Repeated versus single blood pressure measurement.

Long-Term Premorbid Blood Pressure and Cerebral Small Vessel Disease Burden on Imaging in Transient Ischemic Attack and Ischemic Stroke.

Background and Purpose- Studies of causes of cerebral small vessel disease (SVD) should fully adjust for blood pressure (BP), but most etiological studies use a single BP measurement or history of hypertension, which might underestimate the role of hypertension. In patients with transient ischemic attack and ischemic stroke, we therefore compared the associations of baseline and long-term premorbid BP with measures of SVD on magnetic resonance imaging brain. Methods- We studied 1009 transient ischemic attack/ischemic stroke patients who had a brain magnetic resonance imaging, in the population-based OXVASC (Oxford Vascular Study), and related baseline and 20-year premorbid BP (median: 15 readings/patient) to the total SVD score on imaging. Results- SVD score was associated with increasing mean baseline systolic BP (SBP; odds ratio of top versus bottom BP quartile: 2.28; [95% CI, 1.62-3.21]; P<0.0001) and with prior hypertension (2.53; [95% CI, 2.01-3.20]; P<0.0001), but the association was much stronger with mean premorbid SBP (6.09; [95% CI, 4.34-8.55]; P<0.0001). Mean diastolic BP at baseline was negatively associated with SVD score (0.71; [95% CI, 0.51-1.00]; P=0.050), and a positive association was only evident for diastolic BP 10 to 20 years previously (3.35; [95% CI, 2.33-4.84]; both P<0.0001). Relationships between overall mean premorbid BP and SVD burden were strongest in patients age <70 (SBP: 6.99; 4.11-11.86; diastolic BP: 3.13; 1.95-5.07; both P<0.0001) versus ≥70 years (2.37; 1.42-3.94; P=0.001; and 1.16; 0.74-1.84; P=0.52). Conclusions- Mean premorbid SBP is more strongly associated with SVD burden than baseline SBP or history of hypertension, and baseline diastolic BP yields a misleading estimate of the likely etiological importance of midlife hypertension for the subsequent development of SVD. Studies of novel potential etiological factors for SVD should aim to adjust for long-term prior BP, and trials of BP lowering with only a few years of follow-up may underestimate the overall impact on SVD.

New non-invasive indexes of arterial stiffness are significantly correlated with severity and complexity of coronary atherosclerosis

ABSTRACTBackground: Endothelial dysfunction and increased arterial stiffness gradually develop before the manifestation of catastrophic cardiovascular events. Therefore, detection and assessment of vascular function are required to address pre-existing pathological conditions. However, the currently available diagnostic devices and methods are insufficient due to variability among investigators and the time-consuming nature of manual procedures. Methods: Recently, novel devices were developed for the detection of both arterial stiffness and endothelial dysfunction in a single blood pressure measurement using a cuff-oscillometric technique (AVE-1500, Shisei Datum, Japan). API (arterial pressure volume index) is defined as the reciprocal of the slope of the tangent of the brachial artery pressure-volume curve, and AVI (arterial velocity pulse index) is defined as the ratio of the difference between the ejection and reflection waves. In the present study, we performed retrospective, cross-sectional analyses of subjects (n = 102; mean age = 70.5 ± 10.4 years) with detailed coronary angiographic examinations and clinical background parameters. Results: After adjusting for various variables using multiple linear regression analyses, we found that API, but not AVI, was significantly correlated with coronary artery severity and complexity scores. Conclusions: We propose that API may be a new vascular index useful for monitoring and assessing the severity and complexity of atherosclerosis in subjects with coronary artery disease and for evaluating atherosclerotic diseases.

Comparative Analysis of Arterial Stiffness and Body Composition in Early and Late Periods After Kidney Transplantation

IntroductionDiseases of the cardiovascular system are the most common cause of death in patients after kidney transplantation (KTx). Pulse wave velocity (PWV) measurement is a simple, noninvasive, and increasingly popular method to assess arterial stiffness, and thus to assess cardiovascular risk. The aim of the study was to compare arterial stiffness and body composition in patients after KTx in the early and late postoperative periods. MethodsThis research was carried out from January to November 2017 at two locations: (1) Department and Clinic of General and Transplant Surgery and (2) Nephrology and Transplantology Clinic Medical University of Warsaw, the Infant Jesus Teaching Hospital, Warsaw, Poland. The study group consisted of 30 patients in the early postoperative period (2–7 postoperative days) and 151 patients in the late period (6 months to 27 years) after KTx. A single blood pressure measurement, PWV, was performed using a Schiller BR-102 plus PWV. Body composition analysis was performed using a Tanita MC-780 device. ResultsThe average PWV for patients in the early period after KTx was 8.02 ± 2.21 m/s and in the late period 8.09 ± 1.68 m/s. Positive correlations were found between adipose tissue in the abdominal cavity (R = 0.444, P = .033) and PWV value. There was no correlation between the values of PWV and time after transplantation (R = 0.034, P = .777). Upon analyzing patients after transplantation and taking into account the type of dialysis therapy, lower systolic blood pressure (142 ± 21 mm Hg vs 156 ± 24 mm Hg) and diastolic blood pressure (84 ± 13 mm Hg vs 98 ± 11 mm Hg) values were observed in patients treated with hemodialysis compared with those treated with peritoneal dialysis. ConclusionUsing PWV measurement, we found that arterial stiffness levels were similar for early and late periods after transplantation.

Changes in Blood Pressure During Young Adulthood and Subsequent Kidney Function Decline: Findings From the Coronary Artery Risk Development in Young Adulthood (CARDIA) Study

Many studies have focused on the association between a single blood pressure (BP) measurement and risk for adverse outcomes. However, the association of BP trajectories during young adulthood with subsequent decline in kidney function has not been well defined. Observational cohort study. 3,429 participants in the Coronary Artery Risk Development in Young Adulthood (CARDIA) Study enrolled between the ages of 18 and 30 years. BP slope during the first 10 years of participation in CARDIA, derived from linear mixed models incorporating all repeated BP measures. Decline in estimated glomerular filtration rate (eGFR) during the interval between years 10 and 20 of CARDIA participation using cystatin C measured at years 10, 15, and20. Mean age of CARDIA participants at year 0 was 25.1 years, 56% were women, and 53% were white. Every 10-mmHg higher level of systolic (SBP) and diastolic BP (DBP) in year 10 was associated with change in eGFR of-0.09 (95% CI,-0.13 to-0.06) and-0.07 (95% CI,-0.12 to-0.03) mL/min/1.73m2 per year, respectively. Every 10-mmHg increase in SBP slope between years 0 and 10 was associated with a subsequent-0.52 (95% CI,-1.02 to-0.03) mL/min/1.73m2 per year change in kidney function after adjustment for comorbid conditions and SBP at year 10. Similarly, every 10-mmHg increase in DBP slope between years 0 and 10 was associated with a subsequent change in kidney function of-0.65 (95% CI,-1.23 to-0.07) mL/min/1.73m2 per year, after adjustment for comorbid conditions and DBP in year10. Observational design. During young adulthood, increasing SBP and DBP are associated with a higher rate of subsequent kidney function decline, independent of BP measured at the beginning of eGFR assessment.

The importance of accurate methodology in ABPI calculation when assessing lower limb wounds.

Recent health economic publications have highlighted the cost of wound care and demonstrated the important role played by community and practice nurses in delivering care. Leg ulcers form a significant proportion of the wounds managed in the community. Data indicates that many patients are managed with no specific diagnosis or without calculation of the ankle brachial pressure index (ABPI), despite care guidelines emphasising the importance of a full assessment including Doppler ABPI calculation in patient management. This article highlights the important role Doppler ABPI plays in patient assessment and describes the methodology, focusing on the importance of correct application of the technique if reliable reproducible results are to be obtained. The rationale for obtaining blood pressure readings from both arms is discussed, and the possible error resulting from reliance on single upper limb blood pressure measurement for both manual and automated ABPI calculation is highlighted and its impact on ABPI calculation illustrated.

A retrospective analysis of hypertension screening at a mass gathering in India: implications for non-communicable disease control strategies

Cardiovascular disease is the leading case of mortality from non-communicable diseases (NCD) in India. The government's National Programme for Prevention and Control of Cancer, Diabetes, Cardiovascular Diseases and Stroke seeks to increase capacity building, screening, referral and management of NCDs across India, and includes community-based outreach and screening programmes. The government in India routinely provides basic care at religious mass gatherings. However, in 2015, at the Kumbh Mela in Nashik and Trimbakeshwar, the state government extended its services to include a hypertension screening programme. We examine here the value and implications of such opportunistic screening at mass gatherings. At the Kumbh, 5760 persons voluntarily opted for hypertension screening, and received a single blood pressure measurement. In all, 1783 (33.6%) screened positive, of whom, 1580 were previously unaware of their diagnosis. Of the 303 that had previously known hypertension, 240 (79%) were prescribed medications, and 160 were compliant (that is, 52.8% under treatment). Fifty-five (18%) had normal blood pressure readings (BP under control). The data also demonstrated higher prevalence (39%) of hypertension among tobacco users compared to non-users (28%) (P<0.001). Poor recording of phone numbers (0.01%) precluded any phone-based follow-up. The low rates of hypertension awareness, treatment and control underscore the ongoing challenge of both hypertension screening and management in India.

Inter-arm systolic blood pressure differences, relations with future vascular events and mortality in patients with and without manifest vascular disease

BackgroundInter-arm systolic blood pressure difference (SBPD) is an easily obtained patient characteristic which relates to vascular disease. We aimed to identify determinants of large inter-arm SBPD and to investigate the relation between inter-arm SBPD and vascular events in patients with and without manifest vascular disease. MethodsIn a cohort of 7344 patients with manifest vascular disease or vascular risk factors alone enrolled in the Second Manifestations of ARTerial disease (SMART) study, single bilateral non-simultaneous blood pressure measurements were performed. Logistic and Cox regression was used to identify determinants of large inter-arm SBPD (≥15mmHg) and to investigate the relation between inter-arm SBPD and vascular events (composite of non-fatal myocardial infarction, stroke, and vascular mortality) and all-cause mortality. ResultsIn all patients the median inter-arm SBPD was 7mmHg (IQR 3–11) and 1182 (16%) patients had inter-arm SBPD ≥15mmHg. Higher age, higher systolic blood pressure, diabetes mellitus, peripheral artery disease, carotid artery stenosis, higher carotid intima-media thickness, and lower ankle-brachial indices were related to large inter-arm SBPD (≥15mmHg). Each 5mmHg increase in inter-arm SBPD was related to a 12% higher risk of vascular events in patients without manifest vascular disease (HR 1.12; 95% CI 1.00–1.27), whereas no relation was apparent in patients with manifest vascular disease (HR 0.98; 95% CI 0.93–1.04, interaction p-value 0.036). Inter-arm SBPD was not related to all-cause mortality (HR 1.05; 95% CI 0.93–1.19). ConclusionsInter-arm SBPD relates to a higher risk of vascular events in patients without manifest vascular disease, whereas this relation is not apparent in patients with manifest vascular disease.

Diagnostic value of a single blood pressure reading for the detection of latent hypertension in children with chronic kidney diseases

Hypertension is a modifiable risk factor for cardiovascular diseases. The data of 24-hour ambulatory blood pressure monitoring (ABPM) largely correlate with target organ lesions; however, the availability of 24-hour ABPM remains low in clinical practice. Objective. to determine the diagnostic value of a single office blood pressure measurement for the detection of latent hypertension in children with chronic kidney diseases Subjects and methods. A single office blood pressure measurement and 24-hour ABPM were carried out in 359 children (boys/girls, 0,51/0,49; median age, 13 years (5; 17) with chronic kidney diseases (a glomerular filtration rate of 84,18±29,6 ml min/1,73m2 (median, 86 ml/min/1,73m2 estimated using the Schwartz equation). To rule out the impact of antihypertensive and/or immunosuppressive therapy on the results of the study, the investigators identified a group of 108 patients (boys/girls, 0,52/0,48; median age, 12 years (5; 16), estimated median glomerular filtration rate, 84 ml/min/1,73m2 ) who did not receive the above treatment. Results. Office blood pressure measurements revealed prehypertension in 14,5% of cases, hypertension in 27,5%, which was consistent with white coat hypertension in 5% of cases. According to 24-hour ABPM, hypertension was present in 48,7% of the children, including those with latent hypertension (26%). Children with latent hypertension (56,4%) had more frequently elevated blood pressure only at night. The level of office blood pressure was weakly correlated with that of the mean diastolic blood pressure during the day, regardless of the presence/absence of antihypertensive and/or immunosuppressive therapy. Latent hypertension was detected in approximately one-fifth of children with different blood pressure levels in the normal range and its frequency significantly increased 1,5–2-fold in patients with higher-normal blood pressure (90‰ ≤ AP &lt;95‰). The children who did not receive antihypertensive and/or immunosuppressive therapy showed a close correlation between the level of a single office blood pressure measurement and the parameters of 24-hour ABPM, as well as a lower frequency of latent hypertension. The risk of latent hypertension increases significantly when the level of a single office blood pressure is more than 75‰. Conclusion. The normal level of a single office blood pressure reading does not allow latent hypertension to be ruled out in children with chronic kidney diseases. The risk of latent hypertension was significantly higher in patients with a single systolic/diastolic blood pressure measurement of more than 75‰ by gender, age, and height. Regardless of the level of a single office blood pressure measurement, 24-hour ABPM should be therefore carried out in all children with chronic kidney diseases.

Prevalence of Elevated Blood Pressure in HIV-infected Children, Adolescents and Young Adults.

To the Editor: We read with interest the recently published article by Chatterton-Kirchmeier et al1 describing an increased prevalence of high blood pressure (HBP) in HIV-infected youths in the United States. Vertically, HIV-infected subjects appear to show excess risk of cardiovascular events, and we agree with the authors that prompt management of cardiovascular disease risk factors in this population is warranted, although it is frequently overlooked by pediatricians. The prevalence of hypertension reported by Chatterton-Kirchmeier et al,1 however, exceeds the data observed in other cohorts of HIV-infected youths and deserves comment. In 2011, our group enrolled 150 HIV-infected youths and 150 controls in a longitudinal follow-up cohort study addressing cardiovascular risk factors in Madrid.2 Mean age was 14.8 years (range, 2.5–24), and most were Caucasian vertically infected adolescents. Intima-media thickness (IMT), blood pressure (BP) and lipid and glycemic profiles were measured. After adjustment for sex, age and height, the median value of 3 BP measurements was used for diagnosis of hypertension. There was a 2.7% prevalence among HIV+, with no significant differences between HIV-infected and -uninfected controls. Nevertheless, IMT was increased in HIV-infected participants (0.43 vs. 0.42 mm, P = 0.001). Cardiovascular disease in HIV-infected patients might be related to accelerated atherosclerosis, most probably secondary to a series of factors, including direct viral effects, chronic inflammation, T-cell and monocyte activation and antiretroviral treatment-associated metabolic alterations.3 Although several studies have shown increased carotid IMT among HIV-infected children, reported BP values are typically similar to those observed in control subjects.2,4 Chatterton-Kirchmeier et al1 reported a prevalence of hypertension of 19.6% among 107 HIV-infected subjects 2–17 years old. These findings were based on a single BP measurement recorded in medical charts, adjusted for sex, age and height. Because repeated BP measurements in different occasions are widely recommended for the diagnosis of hypertension, we believe that these data must be interpreted very cautiously. Furthermore, the particular characteristics of this cohort might challenge the extrapolation of these findings to other populations. Almost 90% of the study participants were of African American ethnicity, a well-established risk factor for hypertension.5 Fifty-seven percent were male, and the prevalence of cardiovascular risk factors such as tobacco use or obesity (24% and 29%, respectively) was higher than in other cohorts.2,4 Overall, the incidence of past medical conditions associated with HBP was 17%. Exposure of this population to a greater burden of cardiovascular risk factors compared with what has been typically found in other HIV-infected populations is likely to confound the role of HIV infection as a determinant of hypertension. Besides, 33.8% of participants had acquired HIV horizontally, with a mean age of 17.8 years at recruitment, which necessarily implies a short-term exposure to the potential deleterious effects of HIV and antiretroviral treatment. Therefore, based on data from our group and others,1–4 we think that cardiovascular risk factors, and among them BP, should be aggressively sought in HIV-infected subjects, as prompt diagnosis and treatment of cardiovascular disease need to be optimized during infancy and adolescence in this population. In our view, however, the evidence supporting a direct relationship between HIV and HBP remains scarce. Talía Sainz, MD, PhD Department of Pediatrics, Tropical and Infectious Diseases Unit Hospital la Paz and, La Paz Research Institute (IdiPAZ) Sergio Serrano-Villar, MD, PhD Infectious Diseases Department, Hospital Universitario Ramón y Cajal and IRyCIS María José Mellado, MD, PhD Department of Pediatrics, Tropical and Infectious Diseases Unit Hospital la Paz and La Paz Research Institute (IdiPAZ), Madrid, Spain

Effects of Single and Multiple Blood Pressure Measurement Strategies onthe Prediction of Prevalent Screen-Detected Diabetes Mellitus: APopulation-Based Survey.

The authors investigated the effects of single and multiple blood pressure (BP) measurements during the same encounter on screen-detected diabetes risk. Data for 9018 Cameroonian adults from a community-based survey were used. Resting BP was measured three times 5minutes apart. Logistic regressions were used to compute the odd ratio (OR) per standard deviation (SD) higher BP variables. Systolic BP, diastolic BP, and mean arterial pressure (MAP), but not pulse pressure, were related to prevalent diabetes. The highest OR (95% confidence interval [CI]) per SD higher pressure were recorded for MAP (OR, 1.16; 95% CI, 1.05-1.28) and systolic BP (OR, 1.15; 95% CI, 1.04-1.27). Estimates of the association were highest for the first, then third, and lastly the second BP measurements. Estimates from average BP measurements were not better than those from single measurement. Single BP measurement is more effective for diabetes riskscreening than multiple measurements. Community-based diabetes strategies utilizing a single measurement are simple without compromising the yield.

Aortic wall proteomic analysis in spontaneously hypertensive rats with a blood pressure decrease induced by 6-week load-free swimming.

Decreased arterial compliance is one of the earliest detectable manifestations of adverse structural and functional changes within the vessel wall in hypertension. The proteomic approach is a powerful technique to analyze a complex mixture of proteins in various settings. Physical activity level was negatively associated with blood pressure. Sixteen 4-week-old male spontaneously hypertensive rats (SHR) and 16 Wistar-Kyoto (WKY) rats were randomly divided into four groups: i) SHR exercise group, ii) SHR rest group, iii) WKY exercise group and iv) WKY rest group. In the SHR and WKY exercise groups, rats were treated with a 6-week load-free swimming protocol (1 h/day, 5 days/week). The blood pressure of the rats was tested by the CODATM2 single non-invasive blood pressure measurement appliance. After the 6-week swimming protocol, the total aorta excluding abdominal aorta was extracted. The proteins were separated by two-dimensional gel electrophoresis and identified via LC-mass spectrometry (MS)/MS. After 6-week load-free swimming, blood pressure decreased in the SHRs. Compared with sedentary SHRs, 11 spots on the 2D-gel showed a significant difference in exercised SHRs. Nine of these were chosen for further identification. There were 5 upregulated proteins (long-chain specific acyl-CoA dehydrogenase, heat shock protein β-1, isocitrate dehydrogenase subunit α, actin, α cardiac muscle 1 preprotein and calmodulin isoform 2) and 4 downregulated proteins (adipocyte-type fatty acid-binding protein, tubulin β-2C chain, 78 kDa glucose-regulated protein precursor and mimecan). Proteomics is an effective method to identify the target proteins of exercise intervention for hypertension.

Estimated confidence interval from single blood pressure measurement based on algorithmic fusion

Background: Current oscillometric blood pressure measurement devices generally provide only single-point estimates for systolic and diastolic blood pressures and rarely provide confidence ranges for these estimates. A novel methodology to obtain confidence intervals (CIs) for systolic blood pressure (SBP) and diastolic blood pressure (DBP) estimates from a single oscillometric blood pressure measurement is presented.Methods: The proposed methodology utilizes the multiple regression technique to fuse optimally a set of SBP and DBP estimates obtained through different algorithms. However, the set of SBP and DBP estimates is a small number to determine the CI of each individual subject. To address this issue, the weighted bootstrap approach based on the multiple regression technique was used to generate a pseudo sample set for the SBP and the DBP. In this paper, the multiple regression technique can estimate the best-fitting surface of an efficient function that relates the input sample set as an independent vector to the auscultatory nurse measurement as a dependent vector to estimate regression coefficients. Consequently, the coefficients are assigned to an eight-sample set obtained from the fusion of different algorithms as optimally weighted parameters. CIs are also estimated using the conventional methods on the set of fused SBP and DBP estimates for comparison purposes.Results: The proposed method was applied to an experimental dataset of 85 patients. The results indicated that the proposed approach provides better blood pressure estimates than the existing algorithms and, in addition, is able to provide CIs for a single measurement.Conclusions: The CIs derived from the proposed scheme are much smaller than those calculated by conventional methods except for the pseudo maximum amplitude-envelope algorithm for both the SBP and the DBP, probably because of the decrease in the standard deviation through the increase in the pseudo measurements using the weighted bootstrap method for each subject. The proposed methodology is likely the only one currently available that can provide CIs for single-sample blood pressure measurements.

Abstract P349: A Randomized Trial of a High Potassium Dietary Intervention to Lower Blood Pressure in Urban African Americans With Hypertension in the Primary Care Setting: The “Five Plus Nuts and Beans” Trial

Background: African Americans and persons with low income have greater exposure to poor food environments and are more likely to have deficiencies in micronutrients that lower blood pressure (BP). Objective: We conducted a 2-arm randomized trial to test the hypothesis that delivery of nutritional advice to adopt a diet rich in potassium, tailored to availability of foods from a local supermarket, relevant to patients’ preferences, and combined with provision of targeted foods by a food delivery system, will reduce BP in urban African Americans with hypertension. Methods: We recruited adults with controlled hypertension from an urban primary care clinic in Baltimore City, Maryland, and implemented the trial in partnership with a community supermarket and the Baltimore City Health Department. Participants in the DASH-Plus intervention group received 8 weeks of dietary advice and coach assistance with weekly online ordering of high potassium foods ($30/week) delivered by the supermarket to a neighborhood public library. Participants in the control group received a printed DASH diet brochure along with a debit account of equivalent value at the same supermarket. The primary outcome was BP. Results: We randomized 123 participants and had 100% follow-up. At baseline, mean (SD) age was 58.6 (9.5) years, 71% were women, median household income was $20K-$30K/yr, BMI was 34.5 (8.2) kg/m 2 , and 28% had diabetes. At follow-up, compared to the control group, there was no effect on SBP and DBP, but the intervention group had significant increases in self-reported fruit and vegetable consumption, dietary intake of potassium, and in measured urine potassium excretion, along with a significant decrease in urine sodium excretion (see table). Conclusion: Our intervention program in urban African Americans with controlled hypertension did not reduce BP, but improved dietary patterns. Limitations of this pragmatic trial approach included medication changes during the trial that affected BP and reliance on a single BP measurement at follow-up.

Abstract P044: Ten-Year Blood Pressure Trajectories and Long-Term Risk of Cardiovascular Mortality: The Minnesota Business and Professional Men Study

Introduction: We characterised 10[[Unable to Display Character: &amp;#8209;]]year trajectories of annual blood pressure (BP) measurements and studied the added value on long-term cardiovascular disease (CVD) mortality in comparison to a single baseline BP measurement. Methods: This study is based on data from 266 men, aged 45 to 55 years, who participated in the Minnesota Business and Professional Men Study. BP was measured annually between 1947[[Unable to Display Character: &amp;#8209;]]1957, a time when only very high levels of BP were treated. Men who did not die before 1957 and did not have a history of myocardial infarction or stroke were included. We identified BP trajectories by means of finite mixture group-based trajectory modelling (PROC TRAJ in SAS). For each individual, time to death was defined as the difference in years between 1957 and year of death (the last man died in 2002). Cox proportional hazards analysis was used to examine BP trajectories in relation to CVD mortality. Results: All 266 men died and 142 (53.4%) from CVD, with mean (± sd) time to death 21±10 years. We identified four systolic BP trajectories with baseline mean systolic BP levels ranging from 112 (SBP1) to 165 (SBP4) mmHg. This difference of 53 mmHg in baseline systolic BP level was associated with a hazard ratio (HR) of 2.4 (95% CI: 1.5-3.8) for CVD mortality. From age 45 to 65, mean systolic BP levels of the four trajectories (Figure 1A) increased from 0.4 to 2.1 mmHg/year for SBP1 to SBP4. For systolic BP trajectories, the HR of CVD mortality increased from 1.6 (SBP2) to 4.2 (SBP4), compared to men in SBP1 (Figure 1A). A similar pattern was observed for diastolic BP (Figure 1B). Conclusion: In this population of middle[[Unable to Display Character: &amp;#8209;]]aged US men, the increase in BP was strongest in those with the highest BP levels. Trajectories of BP predicted CVD mortality much better than a single BP measurement.

Impact of Measurement Error on Testing Genetic Association with Quantitative Traits

Measurement error of a phenotypic trait reduces the power to detect genetic associations. We examined the impact of sample size, allele frequency and effect size in presence of measurement error for quantitative traits. The statistical power to detect genetic association with phenotype mean and variability was investigated analytically. The non-centrality parameter for a non-central F distribution was derived and verified using computer simulations. We obtained equivalent formulas for the cost of phenotype measurement error. Effects of differences in measurements were examined in a genome-wide association study (GWAS) of two grading scales for cataract and a replication study of genetic variants influencing blood pressure. The mean absolute difference between the analytic power and simulation power for comparison of phenotypic means and variances was less than 0.005, and the absolute difference did not exceed 0.02. To maintain the same power, a one standard deviation (SD) in measurement error of a standard normal distributed trait required a one-fold increase in sample size for comparison of means, and a three-fold increase in sample size for comparison of variances. GWAS results revealed almost no overlap in the significant SNPs (p<10−5) for the two cataract grading scales while replication results in genetic variants of blood pressure displayed no significant differences between averaged blood pressure measurements and single blood pressure measurements. We have developed a framework for researchers to quantify power in the presence of measurement error, which will be applicable to studies of phenotypes in which the measurement is highly variable.