Neil Atkins

Superiority of ambulatory over clinic blood pressure measurement in predicting mortality: the Dublin outcome study.

The purpose of this study was to determine if ambulatory blood pressure measurement predicted total and cardiovascular mortality over and beyond clinic blood pressure measurement and other cardiovascular risk factors; 5292 untreated hypertensive patients referred to a single blood pressure clinic who had clinic and ambulatory blood pressure measurement at baseline were followed up in a prospective study of mortality outcome. Multiple Cox regression was used to model time to total and cause-specific mortality for ambulatory blood pressure measurement while adjusting for clinic blood pressure measurement and other risk factors at baseline. There were 646 deaths (of which 389 were cardiovascular) during a median follow-up period of 8.4 years. With adjustment for gender, age, risk indices, and clinic blood pressure, higher mean values of ambulatory blood pressure were independent predictors for cardiovascular mortality. The relative hazard ratio for each 10-mm Hg increase in systolic blood pressure was 1.12 (1.06 to 1.18; P<0.001) for daytime and 1.21 (1.15 to 1.27; P<0.001) for nighttime systolic blood pressure. The hazard ratios for each 5-mm Hg increase in diastolic blood pressure were 1.02 (0.99 to 1.07; P=NS) for daytime and 1.09 (1.04 to 1.13; P<0.01) for nighttime diastolic pressures. The hazard ratios for nighttime ambulatory blood pressure remained significant after adjustment for daytime ambulatory blood pressure. These results have 2 important clinical messages: ambulatory measurement of blood pressure is superior to clinic measurement in predicting cardiovascular mortality, and nighttime blood pressure is the most potent predictor of outcome.

Accuracy of the SpaceLabs 90207 determined by the british hypertension society protocol

Results: The three recorders passed the before-use interdevice variability assessment, after which 84% of inflations recorded with these devices during the in-use phase gave valid readings, and the three devices subsequently passed the after-use interdevice variability assessment. The main validation test was carried out on one device in 86 subjects with a wide range of pressures, the results being analysed according to a grading system from A to D. The SpaceLabs 90207 acheived B rating for both systolic and diastolic pressures and also satisfied the criteria for accuracy of the Association for the Advancement of Medical lnstrumentation (AAMI), with an average difference (f s.d.1 of 1 f 7 and 3 f 6 mmHg for systolic and diastolic pressure, respectively. Subject acceptability was good. The manufacturers manual was satisfactory overall, but contained a number of errors and omissions.

European Society of Hypertension International Protocol revision 2010 for the validation of blood pressure measuring devices in adults.

The Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Ireland, dabl Ltd., Blackrock Co., Dublin, Ireland, Hypertension Center, Third University Department of Medicine, Sotiria Hospital, Athens, Greece, Istituto Scientifico Ospedale San Luca, IRCCS, Instituto Auxologico Italiano, Milan, Italy, Societe Francaise d’Hypertension Arterielle, Filiale de la Societe Francaise de Cardiolgie, Paris, France, The Department of Clinical Pharmacology and Therapeutics, Tohoku University Graduate School of Pharmaceutical Science and Medicine, Sendai, Japan, Centre for Epidemiological Studies and Clinical Trials, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China, University Clinic Bonn, Department of Internal Medicine, Bonn, Germany and Guy’s and St Thomas’ Hospitals, London, UK

Ambulatory Arterial Stiffness Index as a Predictor of Cardiovascular Mortality in the Dublin Outcome Study

We hypothesized that the dynamic relation between diastolic and systolic blood pressure over 24 hours provides a measure of arterial stiffness and might, therefore, predict cardiovascular mortality over and above pulse pressure. At baseline, while not on antihypertensive medication, 11 291 patients (mean age, 54.6 years; 5965 women) underwent ambulatory blood pressure monitoring. Using all of the blood pressure readings, we plotted diastolic against systolic blood pressure from each individual and calculated the regression slope. The ambulatory arterial stiffness index (AASI) was defined as 1 minus this regression slope. Over a median follow-up of 5.3 years, 566 cardiovascular deaths occurred, including 151 from stroke and 358 from cardiac disorders. Before and after adjustment for other cardiovascular risk factors, AASI and pulse pressure significantly predicted total cardiovascular mortality. AASI was a stronger predictor than pulse pressure for stroke (mutually adjusted relative hazard ratios for 1 SD increase, 1.21 versus 1.04; P=0.02 versus 0.66) with the opposite trend for cardiac mortality (relative hazard ratios, 1.03 versus 1.21; P=0.63 versus 0.002). In subjects with normal daytime ambulatory blood pressure (<135/<85 mm Hg), AASI was more predictive than pulse pressure of cardiovascular mortality (1.26 versus 0.96; P=0.04 versus 0.70) and of stroke mortality (1.81 versus 1.12; P=0.007 versus 0.58), whereas neither independently predicted cardiac mortality (1.11 versus 0.89; P=0.47 versus 0.40). AASI is a novel measure of arterial stiffness, which can be readily determined from ambulatory blood pressure recordings and which independently predicts cardiovascular mortality, even in normotensive subjects.

TWENTY-FOUR-HOUR AMBULATORY BLOOD PRESSURE IN MEN AND WOMEN AGED 17 TO 80 YEARS : THE ALLIED IRISH BANK STUDY

In order to determine reference values for ambulatory blood pressure, a sample of 815 healthy bank employees (399 men and 416 women), aged 17-79 years, were investigated. Ambulatory blood pressure was recorded over 24 h, taking measurements at 30-min intervals. Blood pressure was also measured by trained observers in the clinic. Ambulatory blood pressure in the 815 subjects averaged 118/72 mmHg over 24 h, 124/78 mmHg during the day (1000-2259 h) and 106/61 mmHg at night (0100-0659 h). Office blood pressure, measured by an observer, was 4/2 mmHg lower (p less than 0.0001) than daytime ambulatory pressure. The 95th centiles for the daytime ambulatory pressure in men were: 114/88 mmHg for the age group 17-29 years (n = 107); 143/91 mmHg from 30-39 years (n = 123); 150/98 mmHg from 40-49 years (n = 109); and 155/103 mmHg in 50-79 year old men (n = 60); for the corresponding age groups in women, the 95th centiles of the daytime pressure were: 131/83 mmHg (n = 174); 132/85 mmHg (n = 149); 150/94 mmHg (n = 55); and 177/97 mmHg (n = 38).

State of the Market: A Review of Ambulatory Blood Pressure Monitoring Devices

The introduction of 24-hour ambulatory blood pressure measurement into clinical practice created a large market for ambulatory blood pressure measurement devices. Forty-three such devices from 31 manufacturers or suppliers are now available to satisfy a market demand that is likely to increase. The aim of this article is to identify the devices available and then to examine critically any validation studies assessing accuracy and performance. Of the 43 devices available 18 have been validated according to the protocols of the Association for the Advancement of Medical Instrumentation (AAMI) or the British Hypertension Society (BHS) in 25 reported studies. In 9 of these studies the protocol was not adhered to, and the results, which are therefore questionable, are noted but not considered further. Fourteen devices were evaluated according to the accuracy criteria of both protocols, and of these 9 fulfilled the requirements. From this review of 43 devices on the market it may be concluded that, at the time of writing, there is published evidence for only 9 devices meeting the generally accepted AAMI and BHS criteria for accuracy and performance; these are the A&D TM-2420 models 6 and 7 and TM-2421, CH-Druck, Nissei ABPM DS-240, Profilomat, QuietTrak, and SpaceLabs SL-90202 and SL-90207.

Diagnosis of White Coat Hypertension by Ambulatory Blood Pressure Monitoring

White coat hypertension (WCH) is common in referred hypertensive patients. Ambulatory blood pressure monitoring (ABPM) is not free from the white coat syndrome. We examined the use of the elevation of the first and last measurements of ABPM for diagnosis of WCH in a hypertensive population that had been referred to a hospital-based hypertension unit. Data were obtained on 1350 patients for clinic and ABPM parameters. WCH, as diagnosed by conventional clinic blood pressure (BP) measurement, was compared with a variety of alternative methods determined from ABPM. In all cases, mean daytime pressure was <135 mm Hg/85 mm Hg with an elevation of clinic BP >/=140 mm Hg systolic or 90 mm Hg diastolic. The definitions tested for this elevation were first hour mean pressure, first reading, maximum reading in first hour, last hour mean pressure, last reading, maximum reading in the last hour and maximum reading in first or last hour. Elevation of the maximum pressure in the first hour or last hour above 140 mm Hg systolic or 90 mm Hg diastolic showed a high level of agreement (kappa=0.91) with classical WCH for diagnosis of the white coat syndrome. Termed ambulatory white coat hypertension, patients with this finding were older than classic white coat patients and had higher daytime (127+/-6/78+/-5 mm Hg versus 121+/-5.5/74+/-6 mm Hg, P<0.005 for systolic and diastolic) and nighttime (114+/-11/67+/-8 mm Hg versus 106+/-9/61+/-6 mm Hg, P<0.005 for systolic and diastolic) pressures. They also had a significantly greater Sokolow-Lyon index (leads V(1)+V(5), 21+/-7 mV versus 18+/-6 mV). Elevation of BP above 140 mm Hg systolic or 90 mm Hg diastolic in the first or last hour of monitoring diagnoses patients with a white coat response in whom there is a higher BP profile than in patients with classic white coat response alone. We suggest, therefore, that this is a better measure of the white coat phenomenon.

Ambulatory blood pressure in normotensive and hypertensive subjects: Results from an international database

Objective To delineate more precisely an operational threshold for making clinical decisions based on ambulatory blood pressure (ABP) measurement by studying the ABP in subjects who were diagnosed as either normotensive or hypertensive by conventional blood pressure (CBP) measurement. Subjects: Twenty-four research groups recruited 7069 subjects. Of these, 4577 were normotensive (CBP 140/90 mmHg), 719 were borderline hypertensive (systolic CBP 141–159 mmHg or diastolic CBP 91–94 mmHg) and 1773 were definitely hypertensive. Of the subjects in the last of these categories, 1324 had systolic hypertension (systolic CBP 21 60 mmHg) and 131 0 had diastolic hypertension (diastolic CBP 295 mmHg). Combined systolic and diastolic hypertension was present in 861 subjects. Hypertension had been diagnosed from the mean of two to nine (median two) CBP measurements obtained at one to three (median two) visits. Results The 95th centiles of the ABP distributions in the normotensive subjects were (systolic and diastolic, respectively) 133 and 82 mmHg for 24-h ABP, 140 and 88mmHg for daytime ABP and 125 and 76mmHg for night-time ABP, respectively. Of the subjects with systolic hypertension, 24% had 24-h systolic ABP 4 33 mmHg. Similarly, 30% of those with diastolic hypertension had 24-h diastolic ABP 432 mmHg. The probability that hypertensive subjects had 24-h ABP below these thresholds tended to increase with age and was two- to fourfold greater if the CBP of the subject had been measured at only one visit and if fewer than three CBP measurements had been averaged for establishing the diagnosis of hypertension. By contrast, for each 1 O-mmHg increment in systolic CBP, this probability decreased by 54% for 24-h systolic ABP and by 26% for 24-h diastolic ABP, and for each 5-mmHg increment in diastolic CBP it decreased by 6 and 9%, respectively. In comparison with 24-h ABP, the overlap in the daytime and night-time ABP between normotensive and hypertensive subjects was of similar magnitude and was influenced by the same factors. Conclusions The ABP distributions of the normotensive subjects included in the present international database were not materially different from those in previous reports in the literature. One-fifth to more than one-third of hypertensive subjects had an ABP which was below the 95th centile of the ABP of normotensive subjects, but this proportion decreased if the hypertensive subjects had shown a higher CBP upon repeated measurement. The prognostic implications of elevated CBP in the presence of normal ABP remain to be determined.

Short report: Ambulatory blood pressure in normotensive compared with hypertensive subjects

Objective: To delineate more precisely an operational threshold for making clinical decisions based on ambulatory blood pressure (ABP) measurement by studying the ABP in subjects who were diagnosed as either normotensive or hypertensive by conventional blood pressure (CBP) measurement. Subjects: Twenty-four research groups recruited 7069 subjects. Of these, 4577 were normotensive (CBP ≥140/90mmHg), 719 were borderline hypertensive (systolic CBP 141–159mmHg or diastolic CBP 91–94mmHg) and 1773 were definitely hypertensive. Of the subjects in the last of these categories, 1324 had systolic hypertension (systolic CBP ≤160 mmHg) and 1310 had diastolic hypertension (diastolic CBP ≤95 mmHg). Hypertension had been diagnosed from the mean of two to nine (median two) CBP measurements obtained at one to three (median two) visits. Results: The 95th centiles of the 24-h ABP distributions in the normotensive subjects were (systolic and diastolic, respectively) 133 and 82 mmHg. Of the subjects with systolic hypertension, 24% had 24-h systolic ABP <133 mmHg. Similarly, 30% of those with diastolic hypertension had 24-h diastolic ABP <82 mmHg. The probability that hypertensive subjects had 24-h ABP below these thresholds tended to increase with age and was two- to fourfold greater if the CBP of the subject had been measured at only one visit and if fewer than three CBP measurements had been averaged for establishing the diagnosis of hypertension. By contrast, for each 10-mmHg increment in systolic CBP, this probability decreased by 54% for 24-h systolic ABP and by 26% for 24-h diastolic ABP, and for each 5-mmHg increment in diastolic CBP it decreased by 6 and 9%, respectively. Conclusions: The ABP distributions of the normotensive subjects included in the present international database were not materially different from those in previous reports in the literature. One-fifth to more than one-third of hypertensive subjects had an ABP which was below the 95th centile of the ABP of normotensive subjects, but this proportion decreased if the hypertensive subjects had shown a higher CBP upon repeated measurement. The prognostic implications of elevated CBP in the presence of normal ABP remain to be determined.

Ambulatory blood pressure monitoring predicts cardiovascular events in treated hypertensive patients--an Anglo-Scandinavian cardiac outcomes trial substudy.

Background Results of the Anglo-Scandinavian cardiac outcomes trial-blood pressure lowering arm (ASCOT-BPLA) showed significantly lower rates of coronary and stroke events in individuals allocated an amlodipine–perindopril combination drug regimen than in those allocated an atenolol–thiazide combination drug regimen. The aims of the ambulatory blood pressure (ABP) substudy of ASCOT were to examine the impact of the two blood pressure (BP)- lowering regimens on ambulatory pressures, test to what extent the between-treatment differences in cardiovascular outcome could be attributed to differences in ABP and assess whether ABP provides predictive information additional to that of clinic blood pressure (CBP) in treated hypertensive patients. Methods and results One thousand, nine hundred and five patients from four ASCOT centres had repeated ABPs performed over a median follow-up period of 5.5 years. As in the whole ASCOT population, CBP values were lower in amlodipine–perindopril-treated patients compared with those treated with atenolol–thiazide [between-regimen difference {95% confidence intervals (CIs)}]: [−1.5 (−2.4 to −0.5)/−1.2 (−1.8 to +0.5) mmHg]. Daytime BP during follow-up was higher in patients treated with amlodipine–perindopril therapy [+1.1 (0.1–2.1)/+1.6 (0.8–2.3) mmHg]; night-time systolic, but not diastolic BP, was lower in patients treated with amlodipine–perindopril therapy [−2.2 (−3.4 to +0.9)/+0.8 (0.0–1.6) mmHg]. The relative risk of a cardiovascular event associated with a 1 SD increment in accumulated mean BP was 1.35 (1.18–1.53) for clinic systolic BP, 1.30 (1.14–1.49) for daytime systolic BP and 1.42 (1.24–1.62) for night-time systolic BP. With adjustment for baseline variables, treatment regimen and clinic systolic BP, the hazard ratios were 1.17 (1.00–1.36) and 1.25 (1.08–1.47) for daytime and night-time systolic BP, respectively. The between-regimen adjusted hazard ratio for cardiovascular events (amlodipine–perindopril therapy versus atenolol–thiazide therapy) was 0.74 (0.55–1.01) and increased to 0.81 (0.60–1.10) after further adjustment for clinic systolic BP. Further, adjustment for night-time systolic BP increased the hazard ratio to 0.85 (0.62–1.16). Conclusion The amlodipine–perindopril and atenolol–thiazide regimens had different effects on daytime and night-time ABP, which may have contributed to the lower rates of events in patients treated with amlodipine–perindopril therapy. Both CBP and ABP were significantly associated with rates of cardiovascular events. ABP nocturnal pressures provided complimentary and incremental utility over CBP in the prediction of cardiovascular risk in treated hypertensive patients. These data support the use of ABP to assess the effect of antihypertensive treatment in clinical practice.