Limited reproducibility of 24-h ambulatory blood pressure monitoring

Abstract

Results of 24-h ambulatory blood pressure monitoring (ABPM) including average blood pressure, variability, and nocturnal dipping are considered the gold standard for diagnosis and the best predictor of the future end organ damage in chronic hypertension. Here we report on the reproducibility of ABPM results for these three measures over a period of months. A total of 35 hypertensive patients (43% female, mean age 64 years), underwent two separate ABPM recordings within 14 weeks, with unchanged medical treatment and lifestyle in the interim. The day and night average blood pressure, dipping status of systolic pressure, and the standard deviation of systolic and diastolic blood pressure as a measure of variability were compared between the two recordings. Individual values for average systolic and diastolic pressures showed only a modest correlation between the two measurements (r?=?0.56, r?=?0.81, p?<?0.01). Standard deviations of 24-h pressure were also positively but weakly correlated (r?=?0.4, p?<?0.001). The occurrence of dipping was reproducible in 71% of the patients. Average blood pressure, pressure variability, and dipping as assessed by ABPM are only moderately reproducible. Clinical decision-making based on single ABPM datasets should be made with caution, and repetition of ABPM seems justified in some cases.     

24-h ambulatory blood pressure and retinopathy in normoalbuminuric IDDM patients

Summary The role of blood pressure elevation in the incidence and progression of diabetic retinopathy is not clearly established and results have been conflicting. Blood pressure and urinary albumin excretion (UAE) are closely related. In order to evaluate the independent relationship between retinopathy and blood pressure elevation, precise information on UAE is essential, as confounding by renal disease (incipient or overt), cannot otherwise be excluded.The aim of the present study was to evaluate the association between diabetic retinopathy and 24-h ambulatory blood pressure (AMBP) in a group of well-characterized normoalbuminuric IDDM patients. In 65 normoalbuminuric (UAE < 20 μg/min) IDDM patients we performed 24-h AMBP (Spacelabs 90 207) with readings at 20-min intervals. Fundus photographs were graded independently by two experienced ophthalmologists. UAE was measured by RIA and expressed as geometric mean of three overnight collections made within 1 week. HbA_{1 c} was determined by HPLC. Tobacco use and level of physical activity were assessed by questionnaire. Fifteen patients had no detectable retinal changes [grade 1], 35 had grade 2 retinopathy; and 15 had more advanced retinopathy [grade 3–6]. Diastolic night blood pressure was significantly higher in patients with diabetic retinopathy compared to patients without retinopathy (68 ± 8 mmHg [grade 3–6] and 65 ± 6 mmHg [grade 2], compared to 61 ± 4 mmHg [grade 1], p = 0.02). Diurnal blood pressure variation was significantly blunted in the patients with retinopathy as indicated by a higher night/day ratio of diastolic blood pressure (84.6 % ± 4 [grade 3–6], and 81.2 % ± 6 [grade 2] compared to 79.1 % ± 4 [grade 1], p = 0.01). Heart rate tended to be higher in patients in group 2 and 3–6 compared to patients without retinopathy with p values of 0.07 and 0.11 for day-time and 24 h values, respectively. Mean HbA_{1 c} increased significantly with increasing levels of retinopathy (p < 0.01). Patients were similar regarding sex, age, tobacco use, and level of physical activity. Notably, UAE was almost identical in the three groups (5.0 × /÷1.7 [grade 1], 3.9 × /÷1.8 [grade 2], and 5.1 × /÷1.6 μg/min [grade 3–6]). In conclusion, night blood pressure is higher and circadian blood pressure variation blunted in patients with retinopathy compared to patients without retinopathy despite strict normoalbuminuria and similar UAE levels in the groups compared. Our data suggest that the association between blood pressure and diabetic retinopathy is present also when coexisting renal disease is excluded. Disturbed diurnal variation of blood pressure is a pathophysiological feature related to the development of both retinopathy and nephropathy in IDDM patients. [Diabetologia (1998) 41: 105–110] Received: 27 May 1997 and in revised form: 5 September 1997     

Brachial artery vasomotor function is inversely associated with 24-h ambulatory blood pressure

BACKGROUND: Impaired endothelial function has been reported in hypertensive individuals. The extent to which such changes reflect the co-existence of other cardiovascular disease risk factors rather than an independent association with blood pressure remains uncertain. OBJECTIVE: To assess the relationship between brachial artery vasomotor function and ambulatory blood pressure in hypertensive individuals and normotensive controls. METHODS: We assessed 24-h ambulatory blood pressure and brachial artery endothelial and smooth muscle function in 155 patients with hypertension and 40 normotensive controls. The vasomotor functions were determined by ultrasonographic assessment of vasodilator responses to flow and sublingual glyceryl trinitrate, respectively. Patients with hypertension were categorized as either treated (n = 85) or untreated (n = 70), and further subdivided on the basis of either no or at least one other cardiovascular risk factor. These included hyperlipidaemia, smoking, diabetes or a previous coronary or cerebrovascular event. RESULTS: Age- and sex-adjusted flow-mediated and glyceryl trinitrate-mediated responses were not significantly different in hypertensive individuals with respect to treatment status or the presence of risk factors when compared with controls. However, when data from all 195 study participants were pooled, 24-h ambulatory systolic blood pressure was inversely related to flow-mediated response (P = 0.002), and both systolic and diastolic blood pressure were inversely related to glyceryl trinitrate response (P < 0.001 and P = 0.009, respectively). Observed relationships were largely unaltered after further adjustment for body mass index, antihypertensive treatment or the presence of other risk factors. CONCLUSIONS: The finding of a direct and inverse relationship between the level of ambulatory blood pressure and flow-mediated and glyceryl trinitrate responses is consistent with a direct influence of blood pressure on conduit vessel vascular function.     

Impact of gender on 24-h ambulatory blood pressure and target organ damage

Differences between male and female subjects in mean 24 h blood pressure (BP) values and target organ damage such as left ventricular mass (LVMASS) and intima-media thickness (IMT) of carotid arteries were explained. The study population consisted of 1,445 subjects. All subjects underwent 24 h ambulatory BP monitoring, left ventricular echocardiography and measurement of IMT of carotid arteries. Men and women did not differ in age, body mass index (BMI) and clinic BP values. Mean 24 h systolic and diastolic BP were significantly higher in men compared to women. LVMASS corrected for body surface area or height(2.7), IMT of common (MCCA) and internal (MICA) carotid arteries were found to be significantly higher in men compared to women. Analysis of covariance showed that men had significantly higher LVMASS, MCCA and MICA than women, after adjustment for BMI, age, smoking status, mean 24 h systolic and diastolic BPs, fasting serum glucose, total cholesterol and triglycerides. These findings indicate that male sex could be an important predictor of higher mean 24 h BP and target organ damage for subjects of similar BMI and clinic BP values.     

Reference thresholds for 24-h, diurnal, and nocturnal ambulatory blood pressure mean values in pregnancy

OBJECTIVES: Several studies have indicated that the use of the 24-h mean of blood pressure, mainly using reference thresholds derived from the general non-pregnancy practice, does not provide a proper test for diagnosis of hypertension in pregnancy. This prospective study examines previously derived reference thresholds for the 24-h, diurnal, and nocturnal mean of blood pressure as potential screening tests for the diagnosis of hypertension in pregnancy. METHODS: We studied 235 normotensive and 168 hypertensive pregnant women, who provided 2430 blood pressure series sampled every 20 min during the day and every 30 min at night for 48 consecutive hours once every 4 weeks from the first obstetric visit until delivery. Sensitivity and specificity for each parameter are based on the comparison of the distributions of mean blood pressure values with reference thresholds previously established from an independent population of 113 pregnant women also evaluated monthly by 48-h ambulatory monitoring throughout gestation. RESULTS: Sensitivity of mean blood pressure values, above 70% at all stages of pregnancy, was higher than that obtained from clinic blood pressure measurements, which were always below 14%. The poorest results were consistently obtained for the nocturnal mean. Sensitivity was similar for the 24-h and the diurnal mean, with values ranging from 71% for diastolic blood pressure in the first trimester of pregnancy to 93% for systolic blood pressure in the third trimester. Systolic blood pressure consistently provided better sensitivity than diastolic blood pressure at all gestational ages. CONCLUSIONS: This prospective study on women systematically studied by 48-h ambulatory monitoring throughout gestation indicates that mean ambulatory blood pressure values provide higher sensitivity and specificity than conventional measurements. Moreover, results indicate that diagnosis of hypertension in pregnancy based on ambulatory blood pressure should be established from thresholds much lower than those currently used in clinical practice.     

Out-patient versus in-hospital ambulatory 24-h blood pressure monitoring in heart transplant recipients

OBJECTIVE: To study the effect of the environment--in-hospital vs. out-patient situation--on blood pressure as measured by ambulatory blood pressure monitoring (ABPM). PATIENTS AND METHODS: Twenty-four hour ABPM was performed sequentially in-hospital and again 9+/-3 days later on an out-patient basis, in 30 consecutive heart transplant recipients (27 men, median age 56 years, median time post-transplant 3 years). The same equipment was used on both occasions, without any interim change in medical treatment. RESULTS: Both systolic and diastolic blood pressure were higher in-hospital than as an out-patient: +7+/-7 and +6+/-5 mm Hg respectively for the 24-h average (P<0.001). Daytime and night-time pressures were affected similarly. Depending on the specific cut-off values used, 37 to 87% of the individual patients were hypertensive in-hospital; 31 to 73% of these had an acceptable blood pressure as an out-patient. The converse was very rare (0 to 3% of the total group). CONCLUSIONS: In heart transplant patients blood pressure as assessed from 24-h ABPM is lower in the home environment than during a hospital stay. The post-transplant attenuation of the circadian variation in blood pressure is not influenced by the environment. Checking an unsatisfactory in-hospital ABPM with an outpatient recording may obviate the need for an (intensified) antihypertensive treatment in a substantial number of patients.     

Experience with noninvasive ambulatory 24-hour blood pressure recording in a community hospital.

In 40 subjects (23 treated with antihypertensive medication), 24-h ambulatory blood pressure was measured with an oscillometric blood pressure monitor (Spacelabs model 90202). We studied applicability in the out-patient department with regard to patient tolerance, correlation with mercury manometer measurements, 24-h blood pressure variability and the use in detecting "white-coat" hypertension. The measurements were tolerated quite well except for complaints of sleep disturbance and local irritation from the cuff. The average percentage of missed measuring points was 9.2%. Correlation between blood pressure with the mercury manometer and the Spacelabs monitor (averages of three consecutive readings) was: systolic 0.87 and diastolic 0.73 (P less than 0.001). No evidence for systematic error between the two methods was found. Diurnal blood pressure variation was significant with an average night-time drop of 12 +/- 15 mmHg systolic and 12 +/- 11 mmHg diastolic. "Office" blood pressure measured with the Spacelabs monitor was in the hypertensive range for 28 patients (systolic greater than or equal to 160 and/or diastolic greater than or equal to 95 mmHg). Only 15 of these subjects still met the hypertension criteria on the basis of mean daytime ambulatory blood pressure values. When ambulatory blood pressures during arbitrary 3-h periods of the daytime were studied, the number of patients with established hypertension did not change. The patients with this "office" or "white-coat" hypertensive response could not be distinguished on the basis of variability in daytime blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)     

Seven-day (24-h) ambulatory blood pressure monitoring,self-reported depression and quality of life scores

OBJECTIVE: Effects of environmental conditions on blood pressure (BP) and heart rate (HR) variations as putative factors underlying the onset of vascular events. METHODS: BP and HR were monitored around the clock for 7 days on 54 residents from Urausu, Hokkaido, Japan. Daytime, night-time, and 24-h means served to identify dippers and non-dippers. Questionnaire-assessed depression and subjective quality of life were related to BP and HR by analyses of variance and linear regression. Statistical significance was at 5%. RESULTS: A circaseptan (about 7-day) component characterizes the 24-h mean and standard deviation (SD) of HR, and the daytime and day-night ratio of systolic BP. The SD of HR is higher on weekends and lower on Mondays and Thursdays. When awake, systolic BP is lowest on Sundays and the day-night ratio is optimal on weekends (Saturdays: 15.7 +/- 9.4%; Sundays: 14.0 +/- 13.2%). Depression was detected in 15 subjects, who had higher mean systolic and diastolic BP values (systolic BP: P = 0.028 Fridays, P = 0.021 Tuesdays; diastolic BP: P = 0.022 Mondays, P = 0.006 daytime Mondays) and a lower day-night ratio of diastolic BP (P = 0.012 Tuesdays, P = 0.005 Wednesdays, and P = 0.038 Thursdays). A depressive mood correlated positively with 24-h averages of systolic (P = 0.037) and diastolic (P = 0.030) BP. CONCLUSIONS: Depression (and subjective quality of life) can affect BP and HR variability. The results indicate the role that psychological factors may play in the pathogenesis of cardiovascular disease. Therapeutic implications are suggested for primary and secondary prevention.     

Assessment of blood pressure in patients with Type 2 diabetes: comparison between home blood pressure monitoring, clinic blood pressure measurement and 24-h ambulatory blood pressure monitoring.

AIMS: To compare a home blood pressure (BP) monitoring device and clinic BP measurement with 24-h ambulatory BP monitoring in patients with Type 2 diabetes mellitus (DM). METHODS: Fifty-five patients with type 2 DM had BP measured at three consecutive visits to the DM clinic by nurses using a stethoscope and mercury sphygmomanometer (CBP). Twenty-four-hour ambulatory BP was measured using a Spacelabs 90207 automatic cuff-oscillometric device (ABPM). Subjects were then instructed in how to use a Boots HEM 732B semiautomatic cuff-oscillometric home BP monitoring device and measured BP at home on three specified occasions on each of 4 consecutive days at varying times (HBPM). RESULTS: Correlations between HBPM and ABPM were r = 0.88, P < 0.001 for systolic BP and r = 0.76, P < 0.001 for diastolic BP, with correlations between CBP and ABPM being systolic r = 0.59, P < 0.001, diastolic r = 0.47, P < 0.001. HBPM agreed with ABPM more closely compared with CBP (CBP +10.9/+3.8 (95% confidence intervals (CI) 6.9, 14.8/1.6, 6.1) vs. HBPM +8.2/+3.7 (95% CI 6.0, 10.3/2.0, 5.4)). The sensitivity, specificity and positive predictive value of HBPM in detecting hypertension were 100%, 79% and 90%, respectively, compared with CBP (85%, 46% and 58%, respectively). CONCLUSIONS: In patients with Type 2 DM, home BP monitoring is superior to clinic BP measurement, when compared with 24-h ambulatory BP, and allows better detection of hypertension. It would be a rational addition to the annual review process. Diabet. Med. 18, 431-437 (2001)     

Noninvasive 24-h ambulatory blood pressure and cardiovascular disease: a systematic review and meta-analysis

OBJECTIVE: We systematically assessed the evidence regarding the association between noninvasive 24-h systolic blood pressure and incident cardiovascular events. METHODS: We searched PubMed, EMBASE, and the Cochrane Library through April 2007. Studies that prospectively followed at least 100 individuals for at least 1 year, and that reported at least one effect estimate of interest were included. Two independent investigators abstracted information on study design, subject characteristics, blood pressure measurements, outcome assessment, effect estimates, and adjustment for potential confounders. RESULTS: We identified 20 eligible articles based on 15 independent cohort studies. The association between 24-h systolic blood pressure and a combined cardiovascular endpoint was assessed in nine cohort studies, including 9299 participants who were followed up to 11.1 years and had 881 outcome events. The summary hazard ratio (95% confidence interval) per 10-mmHg increase of 24-h systolic blood pressure was 1.27 (1.18-1.38) (P < 0.001). Further adjustment for office blood pressure in four studies with 4975 participants and 499 outcome events provided a similar summary estimate [hazard ratio (95% confidence interval) per 10-mmHg increase of 24-systolic blood pressure 1.21 (1.10-1.33) (P < 0.001)]. Office blood pressure was usually assessed on a single occasion. We found no significant variability according to age, sex, population origin, baseline office blood pressure, follow-up time, diabetes, or study quality. There was a consistent association between 24-h systolic blood pressure and stroke, cardiovascular mortality, total mortality, and cardiac events with hazard ratio (95% confidence interval) per 10 mmHg increase of 24-h systolic blood pressure of 1.33 (1.22-1.44), 1.19 (1.13-1.26), 1.12 (1.07-1.17), and 1.17 (1.09-1.25), respectively. CONCLUSION: 24-h systolic blood pressure is a strong predictor of cardiovascular events, providing prognostic information independent of conventional office blood pressure.     

Characteristic findings on 24-h ambulatory blood pressure monitoring in a series of patients with Parkinson's disease

BACKGROUND: Patients with Parkinson's disease frequently present with orthostatic hypotension, prompting testing with 24-h ambulatory blood pressure monitoring (ABPM). The aim of our study was to identify characteristic patterns of blood pressure changes present on ABPM in a series of patients with Parkinson's disease. METHOD: We retrospectively identified 13 patients with Parkinson's disease who had undergone ABPM for evaluation of symptomatic orthostatic hypotension. The ABPM tracings were analyzed for the presence or absence of reversal of circadian pattern, postprandial hypotension, noncompensatory heart rate variability, and average daytime and nocturnal blood pressure values. RESULTS: Reversal of circadian rhythm was identified in 92.3%, postprandial hypotension in 100% and nocturnal hypertension in 100% of the cases. Some 61.5% of the patients exhibited daytime blood pressures in the prehypertensive range, and 23% had blood pressures in the stage 1 hypertension range per JNC 7 classification. CONCLUSION: The characteristic findings on 24-h ABPM in this series of patients with Parkinson's disease were the presence of reversal of circadian rhythm (93%), postprandial hypotension (100%) and nocturnal hypertension (100%).     

Effects of the long-acting calcium channel blocker barnidipine hydrochloride on 24-h ambulatory blood pressure

The effect of the long acting calcium channel blocker, barnidipine hydrochloride (barnidipine) on 24-h ambulatory blood pressure (ABP) was evaluated in J-MUBA (Japanese Multicentre Study on Barnidipine with Ambulatory Blood Pressure Monitoring). Following an observation period of two weeks, antihypertensive treatment with barnidipine was continued for at least six months. At the end of each period, ABP were measured. The patients were divided into high- and low-range groups based on ABP measurement. Throughout the 24 h, barnidipine exerted an excellent antihypertensive effect in the high-range group, but not in the low-range group. Barnidipine had comparable effects in the daytime and nighttime in inverted dippers and non-dippers, but it was more effective on daytime ABP than on nighttime ABP in dippers and in extreme dippers. Morning blood pressure before and after waking was evaluated before and after barnidipine administration in 233 patients. Barnidipine inhibited increases in blood pressure before and after waking, especially in surge-type patients whose blood pressure increased rapidly after waking. A positive correlation among 24-h ABP, daytime and night time ABP, morning blood pressure, and clinic blood pressure during the observation period and the antihypertensive effect of barnidipine was observed, with barnidipine exhibiting stronger antihypertensive effects in patients with persistently high blood pressure. It was concluded that the antihypertensive effects of barnidipine are maintained for 24 h but it has no excessive hypotensive effects on lower blood pressure and is thus a safe antihypertensive agent.     

早期慢性肾病患者动态血压变化与微量白蛋白尿的关系

目的分析早期慢性肾脏病（CKD）患者24h动态血压变化与尿微量白蛋白排泄率（UMAER）的关系。方法以25例正常人作为对照组（N组）,71例肾功能稳定的CKD1期患者作为疾病组（D组）。收集24h动态血压监测（ABPM）资料及肾功能、尿微量白蛋白（UMA）、尿肌酐（UCr）等临床资料,计算UMAER及其对数,分析早期D组24h动态血压变化特点及其与微量白蛋白尿（MAU）的关系。结果与N组相比,D组夜问收缩压、昼、夜及24小时平均舒张压均升高（P均〈0．05）;夜间收缩压下降率及舒张压下降率均低下（P均〈0．05）。D组高血压及非杓型血压发生率分别达47．9％、62．0％。与杓刭血压组相比,非杓型血压组Ln（UMAER）值及MAU发生率均增高（P均〈0．01）。相关性分析显示UMAER与夜间收缩压呈正相关（P〈0．05）、与夜间收缩压下降率及夜间舒张压下降率均呈负相关（P均〈0．05）。结论早期CKD患者即已出现血压升高及血压节律改变;MAU产生与早期CKD患者夜间高血压及非杓型血压关系更密切。     

Structural cardiac changes in relation to 24-h ambulatory blood pressure levels in borderline hypertension

Abstract. Objectives. To investigate left ventricular hypertrophy (LVH) in relation to 24-h ambulatory blood pressure (24-ABPM) and insulin levels in borderline hypertension. Design. A case-control study. Subjects. Borderline hypertensive men (diastolic blood pressure (DBP) 85–94 mmHg, n = 69) and age-matched normotensive controls (DBP ≤ 80 mmHg. n = 69) from a population screening programme. Main outcome measures. Echocardiography (M-mode). insulin (RIA) and 24-APBM (Del Mar P-IV) levels. Results. The borderline group showed a significant increase in septal thickness (10.4±1.5 vs. 9.7±1.5 mm. P < 0.01), peak systolic wall stress (218±38 vs. 202±38 10³ dynes cm^?2, P < 0.05) and a decrease in LV ejection time (28.4±2.5 vs. 29.5±2.1s, P < 0.01). The septum vs. posterior wall thickness ratio was significantly higher in the borderline group (1.13±0.14 vs. 1.06±0.14, P < 0.01). Casual BP levels did not correlate with LVH indices, while 24-ABPM systolic levels correlated strongly with LVH indices in the borderline group (r = 0.22–0.52, P < 0.05) but not in the normotensive group. Insulin levels correlates strongly with LVH indices in the normotensive group (r = 0.34–0.47, P < 0.01) but not the borderline, group. Conclusions. Signs of asymmetric LVH and altered ventricular function are already detectable in borderline hypertension. The data also suggest that early structural cardiac changes are related to ambulatory blood pressure profile, but not to casual blood pressure or trophic factors such as insulin.