Diagnostic Thresholds for Ambulatory Blood Pressure Moving Lower: A Review Based on a Meta-Analysis—Clinical Implications

Upper limits of normal ambulatory blood pressure (ABP) have been a matter of debate in recent years. Current diagnostic thresholds for ABP rely mainly on statistical parameters derived from reference populations. Recent findings from the International Database of Ambulatory Blood Pressure in Relation to Cardiovascular Outcome (IDACO) provide outcome-driven thresholds for ABP. Rounded systolic/diastolic thresholds for optimal ABP were found to be 115/75 mm Hg for 24 hours, 120/80 mm Hg for daytime, and 100/65 mm Hg for nighttime. The corresponding rounded thresholds for normal ABP were 125/75 mm Hg, 130/85 mm Hg, and 110/70 mm Hg, respectively, and those for ambulatory hypertension were 130/80 mm Hg, 140/85 mm Hg, and 120/70 mm Hg. However, in clinical practice, any diagnostic threshold for blood pressure needs to be assessed in the context of the patient's overall risk profile. The IDACO database is therefore being updated with additional population cohorts to enable the construction of multifactorial risk score charts, which also include ABP.     

Diagnostic thresholds for ambulatory blood pressure moving lower: a review based on a meta-analysis-clinical implications.

Upper limits of normal ambulatory blood pressure (ABP) have been a matter of debate in recent years. Current diagnostic thresholds for ABP rely mainly on statistical parameters derived from reference populations. Recent findings from the International Database of Ambulatory Blood Pressure in Relation to Cardiovascular Outcome (IDACO) provide outcome-driven thresholds for ABP. Rounded systolic/diastolic thresholds for optimal ABP were found to be 115/75 mm Hg for 24 hours, 120/80 mm Hg for daytime, and 100/65 mm Hg for nighttime. The corresponding rounded thresholds for normal ABP were 125/75 mm Hg, 130/85 mm Hg, and 110/70 mm Hg, respectively, and those for ambulatory hypertension were 130/80 mm Hg, 140/85 mm Hg, and 120/70 mm Hg. However, in clinical practice, any diagnostic threshold for blood pressure needs to be assessed in the context of the patient's overall risk profile. The IDACO database is therefore being updated with additional population cohorts to enable the construction of multifactorial risk score charts, which also include ABP.     

Development of diagnostic thresholds for automated measurement of blood pressures in adults.

In clinical medicine, blood pressure is usually measured by conventional sphygmomanometry. Although it seems simple at first sight, this procedure is fraught with potential sources of error, which may arise from the subject, the observer, the sphygmomanometer or the overall application of the technique. Automated techniques of blood pressure measurement, such as ambulatory monitoring and self-measurement, reduce the limitations of conventional sphygmomanometry. However, the diagnostic thresholds applicable for conventional sphygmomanometry cannot be extrapolated to automated measurements. During the past 10 years criteria for normality have gradually been developed for ambulatory blood pressure (ABP) monitoring of adults. First, the distribution of the ABP in normotensive subjects and untreated hypertensive patients who had initially been recruited and classified on the basis of their conventional blood pressure was studied. Second, authors of various epidemiological studies investigated the distributions of the conventional blood pressure and the ABP in the population at large. Third, authors of several reports attempted to validate the preliminary thresholds for ambulatory monitoring by correlating the ABP to left ventricular hypertrophy, other intermediary signs of target-organ damage or the incidence of cardiovascular morbidity or mortality. Finally, clinical trials should be mounted to prove that it is beneficial to patients as well as cost-effective to diagnose and treat hypertension on the basis of ambulatory monitoring rather than solely under the guidance of conventional sphygmomanometry. For measurements of systolic/diastolic ABP in adults, the proposed upper limits of normotension are 130/80 mmHg for the 24h blood pressure and 135/85 and 120/70 mmHg for the daytime and night-time blood pressures, respectively; for the self-measured blood pressure 135/85 mmHg might be the upper limit of normality. With regard to ABP monitoring, a large database already supports the proposed diagnostic thresholds in terms of their associations with left ventricular hypertrophy and with the incidence of cardiovascular complications; the evidence to validate the thresholds for the self-recorded blood pressure, to a large extent, must still be collected. In conclusion, the newer techniques of blood pressure measurement are now well established in the diagnosis and management of adult subjects with hypertension.     

Relationship between joint national committee-VI classification of hypertension and ambulatory blood pressure in patients with hypertension diagnosed by casual blood pressure

Background: White-coat hypertension has been diagnosed arbitrarily based on different criteria. In 1997, the Joint National Committee-VI (JNC-VI) reported a new classification of hypertension and strongly emphasized the importance of ambulatory blood pressure (ABP) monitoring. The report pronounced normal ABP values for the first time. Hypothesis: The study's aim was to clarify the relationship between casual blood pressure (BP) and ABP of patients with essential hypertension in each stage of JNC-VI classification, and the prevalence of white-coat hypertension diagnosed by using JNC-VI normal ABP criteria. Methods: Ambulatory blood pressure was monitored noninvasively in 232 patients with essential hypertension whose casual BP was ≥ 140/90 mmHg. The patients were classified according to JNC-VI classification, and their casual BP was compared with ABP. The criterion of white-coat hypertension was defined as casual BP ≥ 140/90 mmHg with normal ABP according to JNC-VI criteria (< 135/85 during daytime and < 120/75 during nighttime). Results: Mean ABP increased as the stage advanced, and the differences between casual BP and ABP also increased. There were considerable overlaps in the distribution of ABP among stages. The prevalence of white-coat hypertension was 13% overall: 30% of the patients with isolated systolic hypertension, 19% of those in stage 1,10% in stage 2, and 4% in stage 3. Conclusions: Classification of hypertension based on casual BP may not always correspond in severity to that based on ABP. Ambulatory blood pressure monitoring recommended by JNC-VI is very useful for the evaluation of hypertension to differentiate white-coat hypertension from true hypertension.     

Ambulatory monitoring predicts development of drug-treated hypertension in subjects with high normal blood pressure

BACKGROUND: High normal blood pressure (HNBP), i.e. blood pressure (BP) > or = 130/85 mmHg and <140/90 mmHg, is an important predictor of progression to established hypertension. DESIGN: The purpose of this retrospective study was the evaluation of the predictive value of ambulatory blood pressure monitoring (ABPM) for the development of drug-treated hypertension in subjects with HNBP and other risk factors. METHODS: We studied 127 subjects (69 M, 58 F, age 50 +/- 14 years): 59 subjects had normal BP (NBP: < 130/85 mmHg), 68 subjects had systolic and/or diastolic HNBP. All the subjects underwent ABPM. There were 21/68 (30.9%) subjects in the HNBP group vs. 1/59 (1.7%) in the NBP group with an elevated (>135/85 mmHg) daytime ambulatory blood pressure (ABP) (p < 0.01). RESULTS: After an average follow-up of 103 +/- 28 months, 27 subjects (39.7%) in the HNBP group and 4 subjects (6.8%) in the NBP group developed drug-treated hypertension (p < 0.01). An elevated daytime ABP correctly predicted development of drug-treated hypertension in 17/21 subjects (81%) of the HNBP group and in the only subject of the NBP group. Development of drug-treated hypertension was associated with higher office and ambulatory BP (p < 0.01) and pulse pressures (p < 0.05), longer follow-up (p < 0.05) and higher prevalence of hypercholesterolaemia and smoking (p < 0.01). CONCLUSIONS: We conclude that ABPM correctly predicts development of drug-treated hypertension in most subjects who were identified early as having a daytime mean ABP >135/85 mmHg. ABPM appears to be a useful clinical tool in the early diagnosis of hypertension in subjects with metabolic risk factors and smoking.     

The clinical significance of white-coat and masked hypertension

OBJECTIVE: Self-measured blood pressure (BP) and 24-hour ambulatory blood pressure (ABP) monitoring are used to define the arbitrary clinical categories of masked hypertension (MH) and white-coat hypertension (WCH). Severity of target organ damage and incidence of major cardiovascular events are greater in patients with MH than in patients whose BP is normal both inside and outside the doctor's office. METHODS: We reviewed studies that addressed the prognostic impact of MH and WCH. RESULTS: Overall, WCH was associated with a better outcome and MH to a poor outcome. We, however, need the criteria to identify the clinically normotensive patients at elevated pretest probability of MH in whom a broad use of self-measured home BP and 24-hour ambulatory BP as screening tests may be appropriate and cost effective. Clinical management of patients with MH should continue to be based on current guidelines and mostly related to target organ damage and associated clinical conditions because of the normal values of clinic BP in these patients. WCH is generally defined by the coexistence of persistently high office BP with normal daytime or 24-hour ABP. Daytime ABP normalcy has been defined by values<135/85 mmHg. Data, however, suggest that incidence of cardiovascular events tends to increase consistently above the cut-off value of 130/80 mmHg for daytime BP. CONCLUSION: The long-term outcome of patients with WCH remains uncertain. Data suggesting an increased risk of stroke need to be confirmed in wide-scale studies.     

Diagnostic criteria of white coat hypertension (WCH): consequences for the implications of WCH for target organs

In a sample comprising 51 normotensive subjects and 51 subjects with in-clinic arterial hypertension [blood pressures (BPs) > or = 140/90 mmHg), we investigated the prevalence of target organ damage [left ventricular hypertrophy (LVH) and retinal vasculopathy] in white coat hypertension (WCH) groups defined using: (a) the "optimal ambulatory BP" criterion of the Seventh International Consensus Conference (in-clinic BPs >140/90 mmHg, daytime mean BPs < 130/80 mmHg) and (b) the "normal ambulatory BP" criterion proposed in 1997 by Verdecchia and co-workers (in-clinic BPs >140/ 90 mmHg, daytime mean BPs < 135/85 mmHg), and we compared the results with those obtained for the normotensive group and for a WCH group defined as in a 1996 study of the same data. We found that the newer criteria did not alter the conclusions reached in 1996: namely, that WCH constitutes a state of risk intermediate between normotension and sustained hypertension, which demands in-depth evaluation and active monitoring, if not immediate therapy. We also found that when the WCH group was defined as those patients with in-clinic BPs > or = 140/90 mmHg and 24-h mean BPs < 121/78 mmHg, the prevalence of target organ damage was similar to that found in the control group. We conclude that if WCH status is to imply absence of elevated risk of target organ damage, then the ambulatory BP threshold defining WCH should be lower than the upper limit of ambulatory BPs among subjects who are normotensive in the clinic. The desirability of predicting target organ damage in both hypertensive and normotensive subjects using criteria combining in-clinic BPs, daytime mean ambulatory BPs and night-time mean ambulatory BPs is suggested.     

Normality of ambulatory blood pressure.

An operational threshold for making clinical decision on the basis of ambulatory blood pressure monitoring must be defined. This requires that the relationship between the ambulatory pressure and the incidence of cardiovascular complications be clarified beyond present understanding. Preliminary cut-off points for ambulatory monitoring were derived by averaging the 95th percentiles of the ambulatory blood pressure measurements for the normotensive subjects enrolled in various large-scale studies. According to this approach, the upper limits of normotension, calculated by rounding downwards, would be 130/80mmHg for the 24h blood pressure and 135/85 and 120/70mmHg for the daytime and night-time blood pressures. Abnormality, obtained by rounding upwards, would be blood pressure levels exceeding 135/85, 140/90 and 125/75mmHg, respectively.     

Identification of subjects with white-coat hypertension and persistently normal ambulatory blood pressure

OBJECTIVE: To assess the spontaneous changes in clinic blood pressure, ambulatory blood pressure (ABP) and left ventricular structure in untreated subjects with white-coat hypertension (WCH). DESIGN: A prospective observational study. PATIENTS AND METHODS: In 83 untreated subjects with WCH, 24 h non-invasive ABP monitoring and echocardiographic studies of the left ventricle were repeated after 0.5-6.5 years (mean 2.5) in the absence of antihypertensive drug treatment. WCH was defined by an average daytime ABP < 131/86 mmHg in women and < 136/87 mmHg in men. Ambulatory hypertension was defined by higher ABP values. RESULTS: In the whole population, the clinic blood pressure, ABP and left ventricular mass did not change from baseline to the follow-up visit, whereas the peak A: peak E ratio (where A is the velocity of transmitral blood flow after atrial contraction and E is the velocity during passive left ventricle filling) increased from 0.86 to 0.93. Sixty-three per cent of subjects remained in the WCH category at follow-up study; the remaining 37% shifted to the ambulatory hypertension category. The former group showed no changes in clinic blood pressure, ABP, left ventricular mass and peak A: peak E ratio. The clinic blood pressure of those who developed ambulatory hypertension did not change, whereas their ABP and peak A: peak E ratio increased and their left ventricular mass increased slightly but not significantly. The left ventricular mass increased from baseline to follow-up study by 6.2% in those who developed ambulatory hypertension and decreased by 1.6% in those who remained in the WCH category. The changes in left ventricular mass were associated with the changes in average 24 h systolic blood pressure, but not with the changes in clinic blood pressure. In a stepwise logistic regression analysis, average daytime diastolic blood pressure was the sole variable to enter the model and the probability of ambulatory hypertension at follow-up study was 20.0%percnt; in those with basal daytime ABP <130/80 mmHg, versus 81% in those with higher basal daytime blood pressure levels. CONCLUSION: After 0.5-6.5 years, WCH spontaneously evolved into ambulatory hypertension in 37% of subjects, with an accompanying rise in left ventricular mass. The probability of ambulatory hypertension increased with the baseline values of ABP, rather than with those of clinic blood pressure. WCH might be a prehypertensive state (particularly in subjects with higher baseline ABP levels) and should be defined by low levels of daytime ABP, possibly lower than 130/80 mmHg.     

How reliable is isolated clinical hypertension defined by a single 24-h ambulatory blood pressure monitoring?

BACKGROUND: Isolated clinical hypertension (ICH) is characterized by a persistently elevated clinic blood pressure in the presence of a normal day-time or 24-h ambulatory blood pressure (ABP). This definition is based on a single ABP monitoring (ABPM) and little attention has been focused on the reproducibility of this condition. OBJECTIVE: To investigate the reliability of the criteria currently recommended by major hypertension guidelines to detect ICH based on a single 24-h ABPM session. METHODS: A total of 611 never-treated grade 1 and 2 hypertensive patients (mean age 46 +/- 12 years) referred for the first time to our out-patient clinic, underwent repeated clinic blood pressure measurements, routine investigations, two 24-h periods of ABPM 1-4 weeks apart, cardiac and carotid ultrasound examinations. ABPM was always performed over a working day and the same daily activities were recommended during the two periods. ICH was diagnosed by the following criteria: (i) mean daytime values < 135/85 mmHg or (ii) mean 24-h blood pressure values < 125/80 mmHg during the first ABPM. RESULTS: The overall prevalence of ICH was 7.1% according to criterion (i) and 5.4% according to criterion (ii). Twenty (46.6%) of the 43 patients with mean daytime blood pressure values < 135/85 mmHg during the first ABPM, exceeded this cut-off value during the second ABPM period. Twenty-two (66.6%) of the 33 patients with mean 24-h blood pressure values < 120/80 mmHg during the first ABPM did not confirm a normal blood pressure profile during the second ABPM recording. Cardiovascular involvement was significantly lower in subjects with persistent normal ABP compared to those with non-reproducible ICH pattern or sustained hypertensives. CONCLUSIONS: These findings clearly indicate that: (i) the classification of ICH on the basis of a single ABPM, using the cut-offs suggested by major hypertension guidelines, has a limited short-term reproducibility and (ii) repeated ABPM recordings should be recommended to correctly diagnose patients with ICH and improve cardiovascular risk stratification.     

Comparison of awake ambulatory blood pressure and automated office blood pressure using linear regression analysis in untreated patients in routine clinical practice

The recent American hypertension guidelines recommended a threshold of 130/80 mmHg to define hypertension on the basis of office, home or ambulatory blood pressure (BP). Despite recognizing the potential advantages of automated office (AO)BP, the recommendations only considered conventional office BP, without providing supporting evidence and without taking into account the well documented difference between office BP recorded in research studies versus routine clinical practice, the latter being about 10/7 mmHg higher. Accordingly, we examined the relationship between AOBP and awake ambulatory BP, which the guidelines considered to be a better predictor of future cardiovascular risk than office BP. AOBP readings and 24‐hour ambulatory BP recordings were obtained in 514 untreated patients referred for ambulatory BP monitoring in routine clinical practice. The relationship between mean AOBP and mean awake ambulatory BP was examined using linear regression analysis with and without adjustment for age and sex. Special attention was given to the thresholds of 130/80 and 135/85 mmHg, the latter value being the recognized threshold for defining hypertension using awake ambulatory BP, home BP and AOBP in other guidelines. The mean adjusted AOBP of 130/80 and 135/85 mmHg corresponded to mean awake ambulatory BP values of 132.1/81.5 and 134.4/84.6 mmHg, respectively. These findings support the use of AOBP as the method of choice for determining office BP in routine clinical practice, regardless of which of the two thresholds are used for diagnosing hypertension, with an AOBP of 135/85 mmHg being somewhat closer to the corresponding value for awake ambulatory BP.     

Prognostic superiority of daytime ambulatory over conventional blood pressure in four populations: a meta-analysis of 7,030 individuals

OBJECTIVE: To investigate the multivariate-adjusted predictive value of systolic and diastolic blood pressures on conventional (CBP) and daytime (10-20 h) ambulatory (ABP) measurement. METHODS: We randomly recruited 7,030 subjects (mean age 56.2 years; 44.8% women) from populations in Belgium, Denmark, Japan and Sweden. We constructed the International Database on Ambulatory blood pressure and Cardiovascular Outcomes. RESULTS: During follow-up (median = 9.5 years), 932 subjects died. Neither CBP nor ABP predicted total mortality, of which 60.9% was due to noncardiovascular causes. The incidence of fatal combined with nonfatal cardiovascular events amounted to 863 (228 deaths, 326 strokes and 309 cardiac events). In multivariate-adjusted continuous analyses, both CBP and ABP predicted cardiovascular, cerebrovascular, cardiac and coronary events. However, in fully-adjusted models, including both CBP and ABP, CBP lost its predictive value (P >or= 0.052), whereas systolic and diastolic ABP retained their prognostic significance (P or= 0.21). In adjusted categorical analyses, normotension was the referent group (CBP < 140/90 mmHg and ABP < 135/85 mmHg). Adjusted hazard ratios for all cardiovascular events were 1.22 [95% confidence interval (CI) = 0.96-1.53; P = 0.09] for white-coat hypertension (>or= 140/90 and < 135/85 mmHg); 1.62 (95% CI = 1.35-1.96; P < 0.0001) for masked hypertension (< 140/90 and >or= 135/85 mmHg); and 1.80 (95% CI = 1.59-2.03; P < 0.0001) for sustained hypertension (>or= 140/90 and >or= 135/85 mmHg). CONCLUSIONS: ABP is superior to CBP in predicting cardiovascular events, but not total and noncardiovascular mortality. Cardiovascular risk gradually increases from normotension over white-coat and masked hypertension to sustained hypertension.     

Self-measured versus ambulatory blood pressure in the diagnosis of hypertension

OBJECTIVE: We examined to what extent self-measurement of blood pressure at home (HBP) can be an alternative to ambulatory monitoring (ABP) to diagnose white-coat hypertension. METHODS: In 247 untreated patients, we compared the white-coat effects obtained by HBP and ABP. The thresholds to diagnose hypertension were > or = 140/> or = 90 mmHg for conventional blood pressure (CBP) and > or = 135/> or = 85 mmHg for daytime ABP and HBP. RESULTS: Mean systolic/diastolic CBP, HBP and ABP were 155.4/100.0, 143.1/91.5 and 148.1/95.0 mmHg, respectively. The white-coat effect was 5.0/3.5 mmHg larger on HBP compared with ABP (12.3/8.6 versus 7.2/5.0 mmHg; P < 0.001). The correlation coefficients between the white-coat effects based on HBP and ABP were 0.74 systolic and 0.60 diastolic (P < 0.001). With ABP as a reference, the specificity of HBP to detect white-coat hypertension was 88.6%, and the sensitivity was 68.4%. CONCLUSION: Our findings are in line with the recommendations of the ASH Ad Hoc Panel that recommends HBP for screening while ABP has a better prognostic accuracy.     

White-coat hypertension: not guilty when correctly defined

The coexistence of persistently high office blood pressure with normal blood pressujre outside the medical setting is often referred to as 'white-coat', 'office' or 'isolated clinic' hypertension. The definition of normal blood pressure outside the medical setting is controversial. In our experience, not only the prevalence of white-coat hypertension, but also left ventricular mass measured echocardiographically and the prevalence of left ventricular hypertrophy in this condition markedly vary on going from more restrictive (lower) to more liberal (higher) limits of ambulatory blood pressure normalcy over quite a narrow range. In a prospective study, cardiovascular morbidities of healthy normotensive controls and subjects with white-coat hypertension did not differ. A more recent analysis of our database supports the use of qujite a restrictive definition of white-coat hypertension (average daytime blood pressure < 130/80 mmHg) in order to identify the minority of subjects who have a low risk of cardiovascular morbid events during the subsequent years. A recent document published by the American Society of Hypertension suggests that slightly higher upper limits of ambulatory blood pressure normalcy (i.e. average daytime blood pressure < 135 mmHg systolic and 85 mmHg diastolic) should be used. In a follow-up study by our group, 37% of subjects with white-coat hypertension spontaneously evolved into cases of ambulatory hypertension, with accompanying increases in left ventricular mass. In that study, the probability of a subject developing ambulatory hypertension increased with the baseline values of ambulatory blood pressure and it was quite low (20%) for those with daytime blood pressures below 130/80 mmHg. In two recent controlled studies, the rate of development of ambulatory hypertension over time for untreated subjects did not differ between the normotensive control group and the group with white-coat hypertension. A final answer regarding the clinical significance of white-coat hypertension will come from very large surveys of the natural history of this condition in the long term. For now, we suggest a verdict of innocence for white-coat hypertension when low values of daytime ambulatory blood pressure (i.e. < 130/80 mmHg) and absence of organ lesions and other risk factors coexist.     

Twenty-four hour ambulatory blood pressure in a population of elderly men

OBJECTIVES: The principal aim was to study ambulatory and office blood pressure in a population of elderly men. We also wanted to describe the prevalence of hypertension and investigate the blood pressure control in treated elderly hypertensives. DESIGN: A cross-sectional study of a population of elderly men, conducted between 1991 and 1995. SUBJECTS: Seventy-year-old men (n = 1060), participants of a cohort study that began in 1970. MAIN OUTCOME MEASURES: Office and 24 h ambulatory blood pressure. RESULTS: Average 24 h blood pressure in the population was 133 +/- 16/75 +/- 8 mmHg, and daytime blood pressure 140 +/- 16/80 +/- 9 mmHg. Corresponding values in untreated subjects (n = 685) were 131 +/- 16/74 +/- 7 and 139 +/- 16/79 +/- 8, respectively. An office recording of 140/90 mmHg corresponded to an ambulatory pressure of 130/78 (24 h) and 137/83 mmHg (daytime) in untreated subjects. In subjects identified as normotensives according to office blood pressure (n = 270), the 95th percentiles of average 24 h and daytime blood pressures were 142/80 and 153/85 mmHg, respectively. The prevalence of hypertension, defined as office blood pressure greater than or = 140/90 mmHg, was 66%. Despite treatment, treated hypertensives (n = 285) showed higher office (157/89 vs. 127/76 mmHg) and 24 h ambulatory (138/78 vs. 122/71 mmHg) pressures than normotensives (P < 0.05). Fourteen per cent of the treated hypertensives had an office blood pressure < 140/90 mmHg. CONCLUSIONS: Our results provide a basis for 24 h ambulatory blood pressure reference values in elderly men. The study confirms previous findings of a high prevalence of hypertension at older age. It also indicates that blood pressure is inadequately controlled in elderly treated hypertensives.     

Significance of white-coat hypertension in older persons with isolated systolic hypertension: a meta-analysis using the International Database on Ambulatory Blood Pressure Monitoring in Relation to Cardiovascular Outcomes population

The significance of white-coat hypertension in older persons with isolated systolic hypertension remains poorly understood. We analyzed subjects from the population-based 11-country International Database on Ambulatory Blood Pressure Monitoring in Relation to Cardiovascular Outcomes database who had daytime ambulatory blood pressure (BP; ABP) and conventional BP (CBP) measurements. After excluding persons with diastolic hypertension by CBP (≥90 mm Hg) or by daytime ABP (≥85 mm Hg), a history of cardiovascular disease, and persons <18 years of age, the present analysis totaled 7295 persons, of whom 1593 had isolated systolic hypertension. During a median follow-up of 10.6 years, there was a total of 655 fatal and nonfatal cardiovascular events. The analyses were stratified by treatment status. In untreated subjects, those with white-coat hypertension (CBP ≥140/<90 mm Hg and ABP <135/<85 mm Hg) and subjects with normal BP (CBP <140/<90 mm Hg and ABP <135/<85 mm Hg) were at similar risk (adjusted hazard rate: 1.17 [95% CI: 0.87-1.57]; P=0.29). Furthermore, in treated subjects with isolated systolic hypertension, the cardiovascular risk was similar in elevated conventional and normal daytime systolic BP as compared with those with normal conventional and normal daytime BPs (adjusted hazard rate: 1.10 [95% CI: 0.79-1.53]; P=0.57). However, both treated isolated systolic hypertension subjects with white-coat hypertension (adjusted hazard rate: 2.00; [95% CI: 1.43-2.79]; P<0.0001) and treated subjects with normal BP (adjusted hazard rate: 1.98 [95% CI: 1.49-2.62]; P<0.0001) were at higher risk as compared with untreated normotensive subjects. In conclusion, subjects with sustained hypertension who have their ABP normalized on antihypertensive therapy but with residual white-coat effect by CBP measurement have an entity that we have termed, "treated normalized hypertension." Therefore, one should be cautious in applying the term "white-coat hypertension" to persons receiving antihypertensive treatment.     

Normal ambulatory blood pressure: a clinical practice-based comparison of two recently published definitions

The European Society of Hypertension (ESH) has issued guidelines for the detection and treatment of hypertension. According to these guidelines, normal 24-h ambulatory blood pressure (ABP) is defined as lower than 125/80 mmHg. Another publication of ESH recommendations for blood pressure (BP) measurement defines normal awake and asleep blood pressure as lower than 135/85 and 120/70 mmHg, respectively. Our aim was to investigate the compatibility of these two recently proposed ABP cutoffs in clinical practice. We analysed 1495 consecutive ABP measurements. In all, 56% of the subjects were female; age 58 +/- 16 years; body mass index 27 +/- 4 kg/m(2); clinic BP 151+/-22/84 +/- 13 mmHg. Two-thirds were treated for hypertension, and 11% for diabetes. Subjects were classified as having normal 24-h BP if the corresponding value was <125/80 mmHg. Normal awake-sleep BP was diagnosed if awake BP was <135/85 mmHg and sleep BP was <120/70 mmHg. Concordance between the cutoffs was found in 93% of the subjects. Among the 7% discordant subjects, 4.5% were hypertensive applying the 24 h, but not awake-sleep, BP values, whereas only 2.5% were hypertensive according to awake-sleep, but not 24 h, BP values (P < 0.005). In Conclusion, in real-life ABP measurement, a good agreement was found between two recently issued ABP normality definitions. However, some subjects are classified as hypertensive only according to one of these methods, more often by the 24-h cutoff of 125/80. This discordance may be significant in large-scale clinical BP monitoring.     

An epidemiological approach to ambulatory blood pressure monitoring:the Belgian Population Study

BACKGROUND: In order to determine reference values for ambulatory blood pressure, a random population sample of 1057 persons, 20-88 years old, was investigated in a geographically defined area of Belgium. This article is the final report on the cross-sectional phase of this population survey. METHODS:Twenty-four-hour ambulatory pressure was recorded at 20 min intervals from 0800 to 2200 h and at 45 min intervals from 2200 to 0800 h. Conventional blood pressure was measured by trained nurses at the participants' homes and also in a subgroup of 532 persons at a locally organized clinic. A conventional blood pressure exceeding 140 mmHg systolic or 90 mmHg diastolic and the taking of antihypertensive drugs were the criteria used to distinguish between normotensive and hypertensive persons. RESULTS: In the 1057 patients, of whom 328 were hypertensive, 24 h, daytime (2200 to 0800 h) and night-time (0000 to 0600 h) pressures averaged 119/71, 125/77 and 108/62 mmHg, respectively. Compared with daytime values, blood pressures at home were 3.5/1.5 mmHg lower in 729 normotensive people but 11.6/4.5 mmHg higher in 328 hypertensive patients. In the normotensive subgroup the 95th percentiles of the 24 h, daytime and night-time pressures were 129/80, 137/88 and 121/72 mmHg, respectively. These boundaries were not materially altered when we considered only the 275 participants who had been normotensive both at home and at the clinic (127/79, 135/87 and 118/72 mmHg, respectively). When, in addition to the Belgian data, other reports on large cohorts were also analysed, the transition from normotension to hypertension on ambulatory measurement was likely to be within the ranges of 130-135/80-85, 135-140/85-90 and 120-125/70-75 mmHg for 24 h, daytime and night-time pressures, respectively. CONCLUSION: In comparison with other population surveys and with the earlier interim reports on the Belgian study, the present analysis produced remarkably consistent results with respect to the distributions of the ambulatory measurements. The working definitions of normality based on the 95th percentiles of the ambulatory measurements in the normotensive participants in the present survey and various other studies need further validation in terms of the incidence of cardiovascular complications. For this purpose, the Belgian participants as well as other cohorts are being prospectively followed.     

高血压患者24小时动态血压分析

对１００例高血压患者进行２４ｈ动态血压监测，结果２４ｈ动态血压波动规律呈双峰双谷状，第一高峰在上午７～１１时左右，第二高峰在下午１６～２１时左右，且收缩压第二高峰值明显高于第一高峰值，２４ｈ动态血压均值昼夜为１３９／８３ｍｍＨｇ，日间为１４０／８６ｍｍＨｇ，夜间为１３６／８０ｍｍＨｇ。血压负荷收缩压为４８％，舒张压为３２％。     

Ambulatory blood pressure normality: experience in the Ohasama Study

OBJECTIVE: To define the reference values of ambulatory blood pressure (APB) using results from the Ohasama study. RESULTS: The distribution criteria of 24 h ABP for the total population of Ohasama were 135/79 (mean + SD), 148/86 (mean + SD), and 146/85 mmHg (95th percentile), and those for normotensive subjects were 129/76 (mean + SD), 142/85 (mean + 2 SD) and 139/81 mmHg (95th percentile). The corresponding criteria [i.e. the 24 h ABP corresponding to 140/90 and 160/95 mmHg casual (clinical) blood pressure of the total population] were 125/76 and 132/76 mmHg. A long-term prospective study based on cardiovascular morbidity and mortality would provide the most meaningful values. For the prognostic criteria, based on nonparametric analysis, the hypertensive range of the 24 h ABP was postulated to be >/= 134/>/= 78 mmHg, whereas that based on parametric analysis was postulated to be >/= 134/ 79 mmHg. The lowest relative hazard was observed at 128/74 mmHg in parametric analysis. Thus, we tentatively propose reference values>/= 135/>/= 80 mmHg for hypertensive 24 ABP and < 125/< 75 mmHg for normotensive 24 h ABP.CONCLUSION: