Anthropometric and lifestyle factors associated with white-coat, masked and sustained hypertension in a Chinese population

OBJECTIVE: We investigated to what extent anthropometric and lifestyle factors contributed to the classification of Chinese individuals into groups with white-coat, masked and sustained hypertension (HT). METHODS: We measured the office and ambulatory blood pressure (BP) in 694 Chinese enrolled in the JingNing population study (45.7% men; mean age, 48.4 years). In multivariate-adjusted analyses, we determined the correlates of both types of BP and the factors contributing to white-coat HT (conventional and daytime BP > or =140/90 and <135/85 mmHg, respectively), masked HT (<140/90 and > or =135/85 mmHg) and sustained HT (> or =140/90 and > or =135/85 mmHg), relative to normotension (<140/90 and <135/85 mmHg). RESULTS: In continuous analyses, the conventional and daytime BPs were positively associated with age, body mass index and urinary sodium, and inversely with urinary potassium. The prevalence of white-coat, masked and sustained HT was 7.8, 10.8, and 35.0%, respectively. In line with the continuous analyses, the risk of sustained hypertension increased with age [odds ratio (OR), 2.11 per 10 years], body mass index (OR, 1.27 per 1 kg/m2) and urinary sodium (OR, 1.18 per 50 mmol/day), but was inversely associated with urinary potassium (OR, 0.34 per 25 mmol/day). Furthermore, the risk of white-coat and masked HT increased with age (OR, 1.79 and 1.40, respectively) and body mass index (OR, 1.14 and 1.12). Women were less likely to have masked hypertension than men (OR, 0.39). CONCLUSIONS: Sex, age, body mass index, and urinary sodium and potassium excretion contribute to the risk of white-coat, masked and sustained HT in Chinese.     

Incidence of cardiovascular events in white-coat, masked and sustained hypertension versus true normotension: a meta-analysis

OBJECTIVE: To perform a meta-analysis on the incidence of cardiovascular events in white-coat hypertension (WCHT), masked and sustained hypertension in comparison with true normotension. METHODS: We searched for individual studies, in which the adjusted relative risk of incident cardiovascular events was assessed in patients with WCHT, masked and sustained hypertension versus normotension in the same study population. For each type of hypertension, the weighted overall hazard ratio (HR) and 95% confidence intervals (CI) were calculated. RESULTS: Seven studies were identified, involving a total of 11 502 participants. Four studies were performed in the population, two in primary care and one in specialist care. Two studies were exclusively on treated hypertensive patients; individuals on antihypertensive treatment were included in all the other studies except one. Cut-off blood pressure was 140/90 mmHg for office blood pressure in all studies and 135/85 mmHg (83 in one study) for out-of-office blood pressure. The average age of the study populations was 63 years; 53% were men. The endpoint consisted of cardiovascular death in one study and of various aggregates of fatal and non-fatal cardiovascular events in the others. During an average follow-up of 8.0 years, there were 912 first cardiovascular events. The overall adjusted HR versus normotension was 1.12 (95% CI 0.84-1.50) for WCHT (P = 0.59), 2.00 (1.58-2.52) for masked hypertension (P < 0.001), and 2.28 (1.87-2.78) for sustained hypertension (P < 0.001). CONCLUSION: The meta-analysis indicates that the incidence of cardiovascular events is not significantly different between WCHT and true normotension, whereas the outcome is worse in patients with masked or sustained hypertension.     

Hypertensive Pregnancy Disorders and Future Renal Disease

Ambulatory blood pressure (BP) monitoring provides valuable information on a person’s BP phenotype. Abnormal ambulatory BP phenotypes include white-coat hypertension, masked hypertension, nocturnal nondipping, nocturnal hypertension, and high BP variability. Compared to people with sustained normotension (normal BP in the clinic and on ambulatory BP monitoring), the limited research available suggests that the risk of developing sustained hypertension (abnormal BP in the clinic and on ambulatory BP monitoring) over 5 to 10 years is approximately two to three times greater for people with white-coat or masked hypertension. More limited data suggest that nondipping might predate hypertension, and no studies, to our knowledge, have examined whether nocturnal hypertension or high ambulatory BP variability predict hypertension. Ambulatory BP monitoring may be useful in identifying people at increased risk of developing sustained hypertension, but the clinical utility for such use would need to be further examined.     

Neurogenic abnormalities in masked hypertension

Patients with hypertension exhibit an increased sympathetic activity. No information exists as to whether this is the case in normotensive individuals in whom there is an increased ambulatory blood pressure, a condition termed "masked" hypertension. We studied 18 middle-aged subjects with masked hypertension in whom we measured muscle sympathetic nerve traffic (peroneal nerve and microneurography) and beat-to-beat arterial blood pressure at rest and during baroreceptor deactivation and activation. Measurements also included anthropometric values and insulin sensitivity (homeostasis model assessment index). Data were compared with those of 20 normotensive subjects, 18 subjects with white-coat hypertension, and 20 patients with "in-office" and "out-of-office" hypertension. All of the individuals were pharmacologically untreated and age-matched with subjects with masked hypertension. Patients with in- and out-of-office and white-coat hypertension displayed resting sympathetic nerve activity values significantly greater than normotensive subjects (75.8+/-2.5 and 70.8+/-2.2 versus 45.5+/-2.0 bursts per 100 heartbeats respectively; P<0.01). This was the case also for masked hypertension (73.5+/-2.4 bursts per 100 heartbeats; P<0.01), the degree of the sympathetic activation being similar for magnitude to that seen in the other 2 hypertensive conditions. Compared with normotensive subjects, baroreflex-heart rate control was significantly attenuated in all of the hypertensive states, whereas baroreflex-sympathetic control was unaffected. Homeostasis model assessment index was increased in patients with in- and out-of-office and white-coat hypertension, with a further increase in masked hypertension and a direct relation with resting sympathetic nerve traffic (r=0.46; P<0.01). These data provide the first evidence that masked hypertension is characterized by a marked sympathetic overdrive. They further show that the neurogenic alterations are coupled with metabolic and baroreflex abnormalities.     

Reproducibility of masked hypertension determined from morning and evening home blood pressure measurements over a 6-month period.

Recently, the existence of so-called masked hypertension has attracted attention. In this study, the reproducibility of masked hypertension determined from morning and evening home blood pressure measurements was examined over a 6-month period. Home blood pressure measurements were taken consecutively for 7 days in volunteers at a company in 2002 and again in 2003. The 503 Japanese subjects (329 male, 174 female, mean age: 39.4 years), who were not taking antihypertensive drugs, were asked to measure their home blood pressure three times every morning and three times every evening. We defined casual blood pressure > or =140 (systolic) or > or =90 (diastolic) mmHg and home blood pressure > or =135 or > or =85 mmHg as hypertension. We also defined normotension as <140 and <90 mmHg in casual blood pressure and <135 and <85 mmHg in home blood pressure. We examined the reproducibility of four blood pressure categories (normotension, hypertension, white-coat hypertension, and masked hypertension) over a 6-month period. When measured in morning home blood pressure, the reproducibility of masked hypertension (59.1%) was significantly higher than that of white-coat hypertension (25.0%) and similar to that of hypertension (67.6%). However, the reproducibility of masked hypertension (23.5%) was similar to that of white-coat hypertension (32.0%) and significantly lower than that of hypertension (66.7%) when determined using evening home blood pressure. The concordances in the four blood pressure categories between the two periods were 0.582 (kappa coefficient) and 0.463 when determined using morning and evening home blood pressure data, respectively. In conclusion, the reproducibility of masked hypertension over a 6-month period was moderate in an urban Japanese population when evaluated by morning home blood pressure.     

Clinic and ambulatory heart rate in sustained and white-coat hypertension

BACKGROUND: Sustained and white-coat hypertensives show hypertension in the office setting but different blood pressure values outside the clinical environment. So far, only a few incomplete data on heart rate are available inside and outside the clinical setting in these groups of patient. The aim of this study was to evaluate clinic and ambulatory heart in sustained hypertensives, white-coat hypertensives and normotensives. METHODS: We selected 236 sustained hypertensives, 236 white-coat hypertensives and 236 normotensives matched for age, gender and body mass index, and with a similar occupation. The subjects had been submitted to clinic evaluation and the non-invasive monitoring of blood pressure and heart rate. White-coat hypertension was defined as clinic hypertension and a daytime blood pressure of less than 135/85 mmHg. RESULTS: The clinic heart rate was significantly higher in sustained hypertensives and white-coat hypertensives than in normotensives (76 +/- 11 versus 75.5 +/- 10 versus 70 +/- 9 beats/min [bpm], respectively, P < 0.05). The daytime heart rate was significantly higher in sustained hypertensives than in white-coat hypertensives and normotensives (79.4 +/- 10 versus 74.6 +/- 8.5 versus 74.5 +/- 8.5 bpm, respectively, P < 0.05), as were the night-time heart rate (67 +/- 8.5 versus 63 +/- 8 versus 63 +/- 8 bpm, respectively, P < 0.05) and 24 h heart rate (76.3 +/- 9 versus 72 +/- 7.8 versus 72 +/- 8 bpm, respectively, P < 0.05). When men and women were analyzed separately, the same trend was observed. CONCLUSIONS: The clinic heart rate is similar in sustained and white-coat hypertensives, but the ambulatory heart rate is lower in white-coat hypertensives. As ambulatory heart rate is more representative of 24 h heart rate load and may be a better indicator of the detrimental effect of heart rate, our findings suggest that white-coat hypertensives are at lower cardiovascular risk than sustained hypertensives.     

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.     

Diagnosis of hypertension in children and adolescents based on home versus ambulatory blood pressure monitoring

OBJECTIVE: To investigate the usefulness of home blood pressure measurements in comparison with ambulatory monitoring in the diagnosis of sustained, white-coat hypertension and masked hypertension in children and adolescents. SUBJECTS AND METHODS: One hundred and two subjects, referred for elevated blood pressure, were assessed with clinic (two visits), home (6 days) and awake ambulatory blood pressure measurements [64 boys, mean age 12.8 +/- 2.9 (SD) years, range 6-18 years]. RESULTS: Office hypertension was diagnosed in 38 subjects, ambulatory hypertension in 31 and home hypertension in 23 (P = 0.07). On the basis of clinic and ambulatory blood pressure, 52% of subjects were normotensive, 20% hypertensive, 18% had white-coat hypertension and 11% masked hypertension, whereas on the basis of clinic and home blood pressure, 55, 15, 23 and 8%, respectively. There was an agreement between ambulatory and home blood pressure in the diagnosis of hypertension in 82 cases (80%). When a 5-mmHg gray zone of diagnostic uncertainty was applied above and below the diagnostic thresholds, there were only eight cases with clinically important disagreement. By taking ambulatory blood pressure as the reference method for the diagnosis of hypertension, the sensitivity, specificity and positive and negative predictive values of home blood pressure were 55, 92, 74 and 82%, respectively, for the diagnosis of white-coat hypertension 89, 92, 70 and 98%, respectively, and for masked hypertension 36, 96, 50 and 93%, respectively. CONCLUSION: In children and adolescents, there is a reasonable agreement between home and ambulatory blood pressure measurements as diagnostic methods in hypertension. Home blood pressure appears to be a useful diagnostic test in this population, particularly for the detection of white-coat hypertension.     

Repeated office blood pressure controls reduce the prevalence of white-coat hypertension and detect a group of white-coat normotensive patients

BACKGROUND: The aim of this study was to evaluate whether repeated office blood pressure controls may change the prevalence of white-coat hypertension among hypertensive patients. METHODS: We studied 221 newly diagnosed, never-treated hypertensive patients, all men, aged 31-60 years. On the first visit, they underwent sitting blood pressure measurements (two readings were taken by mercury sphygmomanometer and averaged) and non-invasive 24 h ambulatory blood pressure monitoring (ABPM) every 15 min. Thereafter, each patient made four further visits over an 8-week period. On each visit, three sitting readings were taken and averaged. On the last visit, ABPM was performed again. Subjects who had hypertension in the clinic but whose daytime ambulatory blood pressure was less than 134/90 mmHg were considered to have white-coat hypertension. RESULTS: On the first visit, all patients were, by definition, clinically hypertensive and ABPM detected a prevalence of white-coat hypertension of 25.8%. On the following visits, the prevalence of clinical hypertensive patients progressively declined; on the last visit, the 82.3% of all patients resulted yet clinical hypertensive: on ambulatory blood pressure 71.9% were sustained hypertensives, whereas 10.4 had white-coat hypertension. Of the patients originally labelled as hypertensive, 17.7% proved to be clinically normotensive: 13.6% had also daytime ambulatory blood pressure in the normal range, whereas 4.1% showed elevated blood pressure during daytime ABPM (white-coat normotensives). CONCLUSION: These data suggest that repeated office blood pressure controls in newly diagnosed hypertensives reduce the number of office hypertensive patients, reduce the number of white-coat hypertensive patients and detect a small group of white-coat normotensive patients.     

Integrating Out-of-Office Blood Pressure in the Diagnosis and Management of Hypertension

Guidelines for the diagnosis and monitoring of hypertension were historically based on in-office blood pressure measurements. However, the US Preventive Services Task Force recently expanded their recommendations on screening for hypertension to include out-of-office blood pressure measurements to confirm the diagnosis of hypertension. Out-of-office blood pressure monitoring modalities, including ambulatory blood pressure monitoring and home blood pressure monitoring, are important tools in distinguishing between normotension, masked hypertension, white-coat hypertension, and sustained (including uncontrolled or drug-resistant) hypertension. Compared to in-office readings, out-of-office blood pressures are a greater predictor of renal and cardiac morbidity and mortality. There are multiple barriers to the implementation of out-of-office blood pressure monitoring which need to be overcome in order to promote more widespread use of these modalities.     

Analysis of ambulatory blood pressure monitoring: the problem of 'white-coat' hypertension, responders and non-responders

OBJECTIVE: To analyse a randomized study undertaken to compare the antihypertensive efficacy of dihydropyridine calcium antagonists in patients with essential hypertension. METHOD: Blood pressure was measured both conventionally by a doctor and by non-invasive ambulatory monitoring. RESULTS: During amlodipine therapy (5 mg once a day for 4 weeks, n = 121), the mean daytime diastolic blood pressure was lowered by 8.2+/-7.1 and 0.9+/-7.4 mmHg (means +/- SD) in patients with a pretreatment daytime diastolic blood pressure >/= 90 (n = 89) and < 90 mmHg (n = 32), respectively. In 60 (67%) among the 89 patients who had an initial daytime diastolic blood pressure >/= 90 mmHg the daytime diastolic blood pressure was lowered by >/= 5 mmHg, with a mean fall of 12.0+/- 5.2 mmHg. The decrease in daytime diastolic blood pressure averaged 0.6+/- 3.5 mmHg in the remaining non-responder patients (n = 29). CONCLUSION:It seems important to evaluate the efficacy of a given antihypertensive drug by analysing patients with white-coat hypertension separately from responders to the medication. This allows one to gain maximum information concerning the effect of therapy in the individual hypertensive patients.     

The sympathetic nervous system in hypertension: assessment by blood pressure variability and ganglionic blockade

OBJECTIVE: To determine if the contribution of the sympathetic nervous system to blood pressure could be evidenced by low-frequency oscillations of systolic blood pressure (LF(SBP)), reflecting vascular sympathetic modulation, or by the decrease in blood pressure after autonomic blockade. DESIGN: We studied multiple system atrophy (MSA) patients, in whom supine hypertension is maintained by residual sympathetic tone ('positive controls'); pure autonomic failure (PAF) patients, in whom supine hypertension is largely independent of sympathetic tone ('negative controls'); essential hypertensive patients (HTN) and normotensive subjects (NTN). RESULTS: Supine systolic blood pressure (SBP) was 204 +/- 8, 185 +/- 6, 177 +/- 9 and 130 +/- 4 mmHg in MSA, PAF, HTN and NTN, respectively. LF(SBP) was higher in MSA and HTN (5.7 +/- 1.5 and 5.8 +/- 1.4 mmHg(2) compared to NTN and PAF (3.3 +/- 0.5 and 1.1 +/- 0.5 mmHg(2). Trimethaphan 2-4 mg/min induced complete autonomic blockade and lowered SBP below 125 mmHg in all NTN and all but one MSA (to 111 +/- 3 and 97 +/- 9 mmHg). SBP remained elevated in PAF (164 +/- 7 mmHg). Responses in HTN were variable; SBP decreased below 125 mmHg in three and remained elevated in four patients. The decrease in LF(SBP) correlated with the reduction in SBP, with a steeper slope in MSA and HTN compared to NTN (29.0 +/- 5.5, 8.4 +/- 1.6 and 3.6 +/- 1.2 mmHg/mmH (2), respectively). CONCLUSION: Ganglionic blockade, alone or coupled to LF(SBP), discriminated between human models of sympathetic-dependent (MSA) and independent (PAF) hypertension. This approach may aid in assessing the contribution of the sympathetic nervous system in essential hypertension, in which sympathetic dependence is variably expressed.     

White-coat effect in normotension and hypertension

OBJECTIVES: The difference between clinic and daytime ambulatory blood pressure is referred to as the white-coat effect. In this study, we investigated (i) the magnitude of the white-coat effect in subjects with different daytime ambulatory blood pressure levels, and (ii) the association of the white-coat effect with left ventricular mass. METHODS: A total of 1581 subjects underwent clinic blood pressure readings, 24-h ambulatory blood pressure monitoring and left ventricular echocardiographic assessment. Their mean daytime systolic blood pressure varied from 88.0 to 208.9 mmHg and their mean daytime diastolic blood pressure from 40.3 to 133.0 mmHg. RESULTS: A negative correlation was found between the systolic or diastolic white-coat effect and the systolic or diastolic daytime ambulatory blood pressure (r = -0.22, P < 0.000 and r = -0.50, P < 0.000, respectively). Left ventricular mass significantly correlated with ambulatory blood pressure (P < 0.001), but there was no association between left ventricular mass and clinic blood pressure or white-coat effect. Furthermore, the white-coat effect was reversed at the highest level of systolic or diastolic daytime ambulatory blood pressure (systolic over 170 mmHg or diastolic over 100 mmHg) when systolic or diastolic daytime ambulatory blood pressure was higher than systolic or diastolic clinic blood pressure (ambulatory blood pressure hypertension). CONCLUSIONS: The white-coat effect shows an inverse association with daytime ambulatory blood pressure level (systolic or diastolic), being significantly more prominent for levels below 140/80 mmHg for systolic/diastolic daytime ambulatory blood pressure and reversed with daytime ambulatory blood pressure levels above 170/100 mmHg.     

Masked hypertension and target organ damage in treated hypertensive patients

BACKGROUND: Recent studies have shown that an elevated ambulatory or home blood pressure (BP) in the absence of office BP-a phenomenon called masked hypertension-is associated with poor cardiovascular prognosis. However, it remains to be elucidated how masked hypertension modifies target organ damage in treated hypertensive patients. METHODS: A total of 332 outpatients with chronically treated essential hypertension were enrolled in the present study. Patients were classified into four groups according to office (<140/90 or >or=140/90 mm Hg) and daytime ambulatory (<135/85 or >or=135/85 mm Hg) BP levels; ie, controlled hypertension (low office and ambulatory BP), white-coat hypertension (high office but low ambulatory BP), masked hypertension (low office but high ambulatory BP), and sustained hypertension (high office and ambulatory BP). Left ventricular mass index, carotid maximal intima-media thickness, and urinary albumin levels were determined in all subjects. RESULTS: Of the patients, 51 (15%), 65 (20%), 74 (22%), and 142 (43%) were identified as having controlled hypertension, white-coat hypertension, masked hypertension, and sustained hypertension, respectively. Left ventricular mass index, maximal intima-media thickness, and urinary albumin level in masked hypertension were significantly higher than in controlled hypertension and white-coat hypertension, and were similar to those in sustained hypertension. Multivariate regression analyses revealed that the presence of masked hypertension was one of the independent determinants of left ventricular hypertrophy, carotid atherosclerosis, and albuminuria. CONCLUSIONS: Our findings indicate that masked hypertension is associated with advanced target organ damage in treated hypertensive patients, comparable to that in cases of sustained hypertension.     

Masked nocturnal hypertension and target organ damage in hypertensives with well-controlled self-measured home blood pressure.

It has been reported that masked hypertension, a state in which patients show normal clinic blood pressure (BP) but elevated out-of-clinic BP by self-measured home BP, is a predictor of cardiovascular morbidity much like sustained hypertension. In addition, nocturnal BP is closely associated with cardiovascular disease. This might mean that ambulatory and self-measured home BP monitoring each provide independent information. We performed ambulatory BP monitoring, self-measured home BP monitoring, echocardiography and carotid ultrasonography in 165 community-dwelling subjects. We subclassified the patients according to the ambulatory and self-measured home BP levels as follows: in the masked nocturnal hypertension group, the self-measured home BP level was <135/85 mmHg and the ambulatory nocturnal BP level was >or=120/75 mmHg; in the normotensive group, the self-measured home BP level was <135/85 mmHg and the ambulatory nocturnal BP level was <120/75 mmHg. The intima-media thickness (IMT) and relative wall thickness (RWT) were greater in the masked nocturnal hypertension group than in the normotensive group (IMT: 0.76+/-0.20 vs. 0.64+/-0.14 mm, p<0.05; RWT: 0.50+/-0.14 vs. 0.41+/-0.10, p<0.05). Even in hypertensives with well-controlled self-measured home BP, elevated ambulatory nocturnal BP might promote target organ damage. We must rule out masked hypertension using self-measured home BP monitoring, and we might also need to rule out nocturnal masked hypertension using ambulatory BP monitoring.     

The Norwegian office-, home-, and ambulatory blood pressure study (NOHA)

OBJECTIVES: To evaluate the use of ambulatory blood pressure monitoring in comparison with home and office blood pressure in every-day general practice. METHODS: In a multicenter survey sixty-two practitioners previously unfamiliar with ambulatory blood pressure monitoring performed a total of 1162 (mean 18 +/- 16; range 3-94) 24-h ambulatory- and home blood pressure measurements in normotensive subjects or patients with untreated or treated hypertension. RESULTS: In subjects with office blood pressure <140/90 mmHg average 24-h ambulatory blood pressure (Tenso 24 monitors) was 126/79 mmHg, home blood pressure (Tenso Plus semiautomatic sphygmomanometers) was 128/ 84 mmHg, and office blood pressure (standard sphygmomanometer) was 130/82 mmHg. Patients with office blood pressure > or = 140/90 mmHg had 24-h ambulatory blood pressure averaging 141/88 mmHg, home blood pressure 149/93 mmHg, and office blood pressure 157/95 mmHg. The difference between office-, home-, and ambulatory blood pressure increased with age. Expected differences were found between the three blood pressure modalities according to indication of examination (borderline -, "white-coat" -, and therapy refractory hypertension). Indices of hypertension related end-organ damage were positively correlated with home and ambulatory blood pressure but not with office blood pressure. Overall the performance of home- and ambulatory blood pressure in this general practice setting was similar to that seen by specialized blood pressure units. CONCLUSION: This study demonstrates the practical utility of home- and ambulatory blood pressure measurement in every-day general practice. Both methods are easy to introduce and the quality of blood pressure data obtained in every-day general practice are comparable to those obtained in hypertension clinics and trial centers.     

Controversies in Hypertension III: Dipping,Nocturnal Hypertension,and the Morning Surge

A comprehensive approach to hypertension requires out-of-office determinations by home or ambulatory monitoring. The 4 phenotypes comparing office and out-of-office pressures in treated and untreated patients include normotension, hypertension, white-coat phenomena, and masked phenomena. Components of out-of-office pressure may be equally as important as mean values. Nighttime pressures are normally 10%-20% lower than daytime (normal “dipping”) pressures. Abnormalities include dipping more than 20% (extreme dippers), less than 10 % (nondippers), or rising above daytime (risers) and have been associated with elevated cardiovascular risk. Nighttime pressure may be elevated (nocturnal hypertension) in isolation or together with daytime hypertension. Isolated nocturnal hypertension theoretically changes white-coat hypertension to true hypertension and normotension to masked hypertension. Pressure normally peaks in the morning hours (“morning surge”) when cardiovascular events are most common. Morning hypertension may result from residual nocturnal hypertension or an exaggerated surge and has been associated with enhanced cardiovascular risk, especially in Asian populations. Randomized trials are needed to determine whether altering therapy based solely on either abnormal dipping, isolated nocturnal hypertension, or an abnormal surge is justified.     

The Role of Out-of-Clinic Blood Pressure Measurements in Preventing Hypertension

Purpose of Review

One of the possible strategies for preventing hypertension is identifying high-risk people and then implementing lifestyle modifications or therapeutic interventions. Out-of-clinic blood pressure measurements, either home or ambulatory blood pressure monitoring, may identify people with early blood pressure elevation or white-coat or masked hypertension and potentially help prevent hypertension. In this review, we will summarize the evidence on the role of out-of-clinic blood pressure measurements in preventing hypertension either from prehypertension or high normal or elevated blood pressure, or from white-coat or masked hypertension.

Recent Findings

Early blood pressure elevation, either termed as prehypertension or as high normal or elevated blood pressure, identified by home blood pressure monitoring was associated with a 3- to 5-fold risk of sustained hypertension. White-coat and masked hypertension, identified by either home or ambulatory blood pressure monitoring, was associated with a 2- to 4-fold risk of sustained hypertension.

Summary

Out-of-office blood pressure measurements may potentially help prevent hypertension. However, to prove reversibility, controlled clinical trials are required.

     

Cardiovascular risk in white-coat and sustained hypertensive patients

We compared cardiovascular outcome between patients with white-coat and sustained hypertension who had previously participated in the Ambulatory Blood Pressure Monitoring and Treatment of Hypertension (APTH) trial. Baseline characteristics, including office and ambulatory blood pressure (BP), were measured during the 2-month run-in period of the APTH trial. During follow-up, information on the occurrence of major cardiovascular events (death, myocardial infarction, stroke and heart failure), achieved office BP and treatment status was obtained. At entry, 326 patients had sustained hypertension (daytime ambulatory BP ≥140 mmHg systolic and/or ≥90 mmHg diastolic) and 93 had daytime ambulatory BP below these limits and were classified as white-coat hypertensives. During 2088 patientyears of follow-up (median follow-up 5.3 years), all major cardiovascular events ( n = 22) occurred in the patients with sustained hypertension (rate 12.7 per 1000 patient-years, p = 0.02 for between-group difference). Furthermore, multiple Cox regression confirmed that after adjustment for important covariables, daytime ambulatory BP - but not office BP at entry - significantly and independently predicted cardiovascular outcome. After additional adjustment for office BP, daytime ambulatory BP still predicted the occurrence of major cardiovascular events. Although white-coat hypertension was less frequently associated with antihypertensive drug treatment during follow-up, it carried a significantly better prognosis than sustained hypertension.     

Masked hypertension in obstructive sleep apnea syndrome

BACKGROUND: Ambulatory blood pressure (BP) monitoring (ABPM) detects subjects with normal clinic but high ambulatory 24-h BP, that is, masked hypertension. METHODS: One hundred and thirty newly diagnosed obstructive sleep apnea syndrome (OSAS) patients, free of recognized cardiovascular disease were included (111 men, age = 48 +/- 1 years, BMI = 27.6 +/- 0.4 kg/m, respiratory disturbance index (RDI = 42 +/- 2/h). Clinic BP, 24-h ABPM, baroreflex sensitivity (BRS), echocardiography and carotid intima-media thickness (IMT) were assessed. RESULTS: Forty-one patients (31.5%) were normotensive, 39 (30.0%) exhibited masked hypertension, four (3.1%) white-coat hypertension and 46 (35.4%) hypertension. Significant differences were found between normotensive, masked hypertensive and hypertensive patients in terms of BRS (10.5 +/- 0.8, 8.0 +/- 0.6 and 7.4 +/- 0.4 ms/mmHg, respectively, P < 0.001), carotid IMT (624 +/- 17, 650 +/- 20 and 705 +/- 23 microm, respectively, P = 0.04) and left ventricular mass index (37 +/- 1, 40 +/- 2 and 43 +/- 1 g/height2.7, respectively, P = 0.003). A clinic systolic BP more than 125 and a diastolic BP more than 83 mmHg led to a relative risk (RR) of 2.7 and a 90% positive predictive value for having masked hypertension. CONCLUSION: Masked hypertension is frequently underestimated in OSAS and is nearly always present when clinic BP is above 125/83 mmHg.