The white-coat effect in treated hypertension

OBJECTIVE: To determine the occurrence of the white-coat effect in patients already receiving antihypertensive therapy. METHODS: A review of data from several studies in which the prevalence of a white-coat effect was determined in different populations of patients receiving antihypertensive therapy. RESULTS: In an initial series of 71 treated hypertensive patients being studied in a tertiary care centre, we noted a white-coat effect (office minus ambulatory blood pressure >/= 20/10 mmHg) in 52 patients. This finding was confirmed in a larger series of similar patients with 106 of 152 having a white-coat effect. A white-coat effect was also more common in women (70 of 87) than in men (36 of 65). Similar findings were observed in untreated hypertensive patients in the community with 91 of 147 patients having a white-coat effect on the basis of routine office blood pressure readings taken by family physicians. CONCLUSION: The white-coat effect is common in patients being administered antihypertensive therapy and should be considered as part of their management in clinical practice.     

Estimate of white-coat effect and arterial stiffness

OBJECTIVES: Blood pressure (BP) measured in the office is usually higher than the average ambulatory BP, a difference generally taken as an estimate of the white-coat effect. This study was designed to assess whether such a difference is associated with impairment of the conduit arterial system. METHODS: We calculated the difference between office and average daytime peak systolic blood pressure (DeltaSBP) in 2778 hypertensive participants (1240 women) of the Progetto Ipertensione Umbria Monitoraggio Ambulatoriale cohort. Arterial stiffness was evaluated using an adjusted office pulse pressure to stroke volume ratio (PP/SV), measured at rest, which has previously been shown to predict cardiovascular outcome independent of echocardiographic left ventricular hypertrophy. Effective arterial elastance was also estimated. RESULTS: Across quintiles of PP/SV, significant linear, positive trends were found with age, the proportion of women, plasma glucose and triglyceride levels (0.05 > P < 0.0001). Heart rate measured in the office increased mildly with quintiles of PP/SV (P < 0.05). After adjusting for age, sex, body weight and office heart rate, DeltaSBP progressively increased with increasing quintiles of PP/SV (P for trend < 0.0001), whereas stroke volume decreased, paralleling the increase in left ventricular relative wall thickness (both P < 0.0001) and left ventricular mass index (P < 0.05). The significant increase in effective arterial elastance with quintiles of PP/SV was also independent of peak systolic BP, in addition to age, sex, heart rate and body weight. CONCLUSIONS: The difference between office BP and ambulatory BP, an estimate of the white-coat effect, is strongly associated with increased arterial stiffness, evaluated by a two-element fluid system accumulator.     

Performance of the automated BpTRU measurement device in the assessment of white-coat hypertension and white-coat effect

OBJECTIVES: BpTRU (VSM MedTech Ltd, Vancouver, Canada) is an automated oscillometric device that provides serial blood pressure measurements in an office setting in the absence of a healthcare professional. We sought to determine whether the white-coat effect is reduced by a blood pressure measurement protocol using BpTRU compared with casual office measurements. Secondarily, we also sought to determine whether a blood pressure measurement protocol using BpTRU reduced white-coat hypertension compared with the casual office measurements, and reduced white-coat effect and white-coat hypertension compared with blood pressure obtained by a research nurse. METHODS: Blood pressure was measured in 107 adult hypertensive patients referred for ambulatory blood pressure monitoring using an ambulatory blood pressure monitor, a standardized protocol by a trained research nurse, and a protocol using BpTRU (five readings over 25 min, using the 5-min blood pressure measurement interval setting). Casual office blood pressure was also recorded in the family physicians' offices. Using the mean daytime ambulatory blood pressure as the reference standard, the proportion of patients with white-coat effect and white-coat hypertension were determined for measurements obtained by BpTRU, the research nurse, and the family physicians' offices. RESULTS: Casual office blood pressure measurements demonstrated a white-coat effect in 39 (36.4%) patients; seven (6.5%) patients demonstrated a white-coat effect using BpTRU (P<0.0001). White-coat hypertension was also less common using BpTRU than with the casual office readings (13 vs. 1 patient, P<0.0001). White-coat effect was also reduced with BpTRU compared with the research nurse measurements. Unfortunately, percentage agreement for the diagnosis of hypertension between the protocol using BpTRU and the reference standard was only 48%. This resulted in substantial misclassification of hypertension by the BpTRU measurement protocol. CONCLUSIONS: Although BpTRU reduces white-coat effect and white-coat hypertension, blood pressure is underestimated by the device, leading to misclassification of hypertension. BpTRU, when set at 5-min blood pressure measurement intervals, should not be used in clinical practice.     

Anxiety and outcome expectations predict the white-coat effect

OBJECTIVE: To determine whether elevated clinic blood pressure compared with daytime ambulatory blood pressure, referred to as the white-coat effect, is associated with anxiety and increased blood pressure expectancy in the doctor's office. METHODS: The 24-h ambulatory blood pressure measurements and physicians' blood pressure measurements were obtained in 226 normotensive and hypertensive study participants. Anxiety levels were assessed multiple times during the clinic visit using a Visual Analog Scale. Participants' expectations regarding the clinic visit were assessed using a six-item scale (Expectations of Outcomes Scale). The white-coat effect was computed as the difference between the mean clinic blood pressure and the mean daytime ambulatory blood pressure. Multiple regression analysis was performed to examine the association between anxiety, outcome expectations and the white-coat effect, adjusting for age, sex, and ambulatory blood pressure level. RESULTS: As predicted, outcome expectations and anxiety during the clinic visit were significantly associated with the white-coat effect. Results of the regression analysis indicated that only expectancy had an independent effect on the systolic white-coat effect; however, both anxiety and expectancy had independent effects on the diastolic white-coat effect. CONCLUSION: Our results provide empirical support to the hypothesis that anxiety and blood pressure expectancy may elevate clinic blood pressure.     

影响乙肝疫苗免疫效果的因素

影响乙型肝炎病毒(HBV)疫苗免疫的因素很多,政府和民众对乙型肝炎(乙肝,HB)了解和认识程度、经济等状况、有关行政部门的重视程度和管理力度决定是否推行HBV疫苗免疫接种;接种者的年龄及个体差异、用药情况、疫苗的种类、接种方案、接种方法和剂量、是否辅用佐剂等对接种后能否尽早产生保护性抗-HBs均有不同程度的直接影响．对不同人群、不同个体应采用不同的接种方案和剂量,必要时应用佐剂或免疫调节剂．     

The white-coat hypertension response

This study was designed to determine the clinical characteristics of hypertensive patients whose blood pressures are substantially higher in the medical office than in their natural environments. Thirty-nine percent of patients enrolled in a nonpharmacologic hypertension treatment program had systolic or diastolic office blood pressures (OBPs) that were at least 10 mm Hg higher than their ambulatory blood pressures (ABPs). Although these white-coat responders (WCRs) had higher systolic OBPs than did non-white-coat responders (NRs), both their systolic (p<0.02) and their diastolic (p<0.0001) ABPs were significantly lower than those of NRs. Furthermore, patients with white-coat hypertension did not have greater blood pressure reactivity in their natural environments, suggesting that their blood pressure elevations may be specific to the medical setting. White-coat hypertensives were older (p<0.005), had less angry dispositions (p<0.01), and reported less overt anger expression (p<0.005). They were also taking more antihypertensive medications than were the other patients in the study (p<0.001).     

Determinants of the white-coat effect in normotensives and never-treated mild hypertensives

The prognostic significance of the white-coat effect (WCE) is unclear. Knowledge of the predictors of the WCE may help illuminate the clinical significance of this phenomenon. The purpose of this study was to (i) compare characteristics of subjects demonstrating a WCE, those not demonstrating a WCE, and those demonstrating a reverse WCE and (ii) determine clinical features that may influence the size of the WCE. Forty-one subjects with normotension or mild hypertension who had never been treated with antihypertensive medications were recruited for the study. All subjects underwent a battery of anthropometrical measurements and clinic blood pressure (BP) measurements. To calculate arterial compliance, impedance cardiography was used to measure resting stroke volume in each subject. All subjects performed a laboratory mental stress protocol to determine the size of the BP reactivity. Ambulatory blood pressure (ABP) profiles were studied in each subject with the use of an oscillometric ABP recorder. White-coat effect was determined by subtracting the awake period of the ambulatory systolic blood pressure (SBP) from the clinical SBP. Subjects were grouped according to the size of their WCE. Those who showed a WCE of 5 mmHg and above were assigned to the WCE group; those who showed a WCE of between -5 and 5 mmHg were assigned to the no white coat effect (NWCE) group; those who exhibited a WCE of -5 mmHg and lower were assigned to the reverse white-coat effect (RWCE) group. Subjects with a positive WCE had significantly higher body mass index (BMI) than those without a WCE and those with a RWCE. The WCE group had significantly higher clinic SBP and heart rate (HR) than the RWCE group. Arterial compliance was significantly lower in the WCE group as compared to the NWCE group and the RWCE group. The three groups had comparable ABP profiles. In terms of BP variability, the increase in SBP in response to mental stress did not differ among the three study groups nor did the 24-hour and awake BP variability. For the sample as a whole, clinic HR and clinic-ambulatory SBP difference were higher and arterial compliance were lower in women than in men. Furthermore, clinic SBP significantly correlated with the systolic WCE (r = 0.40, P = 0.009). When men and women were analyzed separately, the correlation between clinic SBP and the systolic WCE was significant in women (r = 0.63, P = 0.001) but not in men (P = 0.95). Multiple linear regression showed that sex (P = 0.013) and clinical SBP (P = 0.003) were the only two variables that significantly influenced the systolic WCE. These two variables together accounted for 29% of the variation in the systolic WCE. In conclusion sex and clinic BP are two major determinants of the WCE. The results of this study indicate that WCE is not related to higher stress reactivity or higher BP variability.     

Clinical implications of white-coat effect among patients attending at a lipid clinic

We evaluated clinical implications of the white-coat effect (WCE) in cardiovascular (CV) risk stratification in the primary prevention setting of a Lipid Clinic. We compared home self blood pressure measurement (SBPM) with office blood pressure (BP) readings and BP measured by a nurse before and after the visit on consecutive subjects, free of previous CV diseases, attending at a Lipid Clinic for a first visit. Additionally, we evaluated whether and to what extent the difference between these measurements affect the 10-year cardiovascular risk calculated according to current guidelines. Mean home self-measured systolic and diastolic BP values were significantly lower than physician's and nurse's readings (p=0.000). A WCE was observed in 60.3% of patients during the physician's visit, and in 33.9% and 36.6% of nurse's measurements before and after visit, respectively. Compared with computation of SBPM, inclusion in risk predictive model of systolic BP values obtained by physician and nurse (before or after visit) resulted in significantly higher calculated CV risk (p=0.000) and in a higher risk-class allocation in 16.5%, 8.5% and 9.4% of patients, respectively (p=0.000). Our findings show that among patients attending at a Lipid Clinic there is a high prevalence of WCE, which is roughly halved when nurse's BP measurements were considered. Nurse's BP measurements before or after the doctor's visit may reduce, but not eliminate at all, the clinic overestimation of BP. The WCE associated with physician's office visit carries a substantial probability of 10-year CV risk overestimation in the primary prevention setting.     

白衣高血压对糖尿病患者血管并发症的影响

目的 探讨白衣高血压对T2DM患者血管并发症发生的影响.方法 T2DM患者测量血压和24 h动态血压监测后分为正常血压（Con）组109例和白衣高血压（WCH）组39例.患者进行糖尿病慢性肾脏疾病（CKD）和DR检查.结果 两组临床和生化指标差异无统计学意义.24 h动态血压监测WCH组日间SBP、脉压、血压水平均高于Con组.WCH组大量白蛋白尿发生率高于Con组（OR=4.9,P＜0.01）;增生性视网膜病变发生高于Con组（OR=3.9,P＜0.01）.结论 患有白衣高血压的T2DM患者发生血管并发症的危险性增加.     

The effect of antihypertensive treatment with dihydropyridine calcium antagonists on white-coat hypertension

OBJECTIVE: To investigate the interrelations between blood pressure variables and treatment effects in white-coat and established hypertensive patients. DESIGN: A substudy on data from a randomized clinical trial on two dihydropyridine calcium antagonists, in which treatment intensity relied on office blood pressure, but with ambulatory blood pressure recordings performed before and after treatment. PATIENTS: Ninety-two hypertensive patients from general practices. RESULTS: Office and ambulatory blood pressures were only poorly correlated (r = 0.27-0.49). There was no significant correlation between treatment effects evaluated in terms of office and ambulatory blood pressures. Seventeen patients were classified as white-coat hypertensives; these differed in that their office blood pressure declined more with placebo, but similarly when administered active treatment, whereas their ambulatory blood pressure was not affected. An initial ambulatory blood pressure amounting to 127.4/84.8 mmHg was associated with no ambulatory treatment effect on average. CONCLUSION: These findings expose the shortcomings of office blood pressure measurements and strengthen the conception that white-coat hypertensives should not be treated pharmacologically.     

Determinants of white-coat hypertension

BACKGROUND: The prevalence of white-coat hypertension (WCH) is considerable in patients referred with elevated office blood pressure. Failure to recognise this phenomenon can lead to the inappropriate use of antihypertensive medications. We undertook this study to determine the profile of patients with WCH. METHODS: Baseline clinic and daytime ambulatory blood pressures were available from 5716 patients referred over a 22-year period. Individuals were considered to have WCH if they had an elevated clinic blood pressure measurement greater than 140/90 mmHg and normal daytime mean ambulatory blood pressure. Mean age was 53.6 years and 53.2% were female. RESULTS: The overall prevalence of white-coat hypertension was 15.4%. A higher prevalence was seen amongst older adults, females, and non-smokers. CONCLUSION: Multivariate logistic regression analysis confirmed these characteristics as independent predictors of WCH.     

Beneficial effect of cilnidipine on morning hypertension and white-coat effect in patients with essential hypertension.

Home blood pressure has a higher predictive power for cardiovascular events than office blood pressure, and there is a particularly close association between morning blood pressure at home and the incidence of cardiovascular events and mortality in the early morning. In this study, we evaluated the efficacy of a long-acting N-type and L-type calcium channel blocker, cilnidipine, in reducing morning blood pressure at home and in ameliorating the white-coat effect. Fifty-eight subjects diagnosed with both essential hypertension and morning hypertension (43 currently being treated, 15 new patients) were prescribed cilnidipine at a dosage of 10-20 mg per day for 8 weeks. After the addition of or a change to cilnidipine, the morning systolic blood pressure (SBP) was controlled to less than 135 mmHg in 25 (58%) out of the 43 patients currently receiving antihypertensive medication. The office SBP in 24 out of those 25 patients was also maintained under 140 mmHg. In the 15 newly treated patients, the morning SBP of 12 patients (80%) was controlled to less than 135 mmHg after administration of cilnidipine. At baseline, 17 patients showed a clear white-coat effect, in which the difference between office blood pressure and home blood pressure was 20/10 mmHg or more. The white-coat effect was depressed significantly after cilnidipine administration. These results suggest that cilnidipine may serve as a useful antihypertensive medication in the treatment of morning hypertension, and also attenuate the white-coat effect in patients with essential hypertension.     

Prevalence of the white-coat effect at multiple visits before and during treatment

OBJECTIVE: To investigate the prevalence and persistence of the white-coat effect (WCE) and white-coat hypertension (WCH) on multiple blood pressure measurement occasions in hypertensive patients with and without treatment. DESIGN: Essential hypertensive patients in whom we took office blood pressure measurements (OBPM) at eight visits (three readings per visit) performed self blood pressure measurements (SBPM) for 1 week prior to each visit (42 readings per week) over a period of 1 year. All measurements were performed with the same automatic device (Omron 705CP). In addition, 24-h ambulatory blood pressure monitoring (ABPM) was performed at the start and at the end of the study. At the start, patients did not use any medication but on subsequent visits they were treated on the basis of their SBPM values. WCH was defined as an OBPM-value > or = 140 and/or 90 mmHg and a SBPM or daytime ABPM value < 135/85 mmHg. This definition was used irrespective of treatment. We also determined the prevalence of a substantial WCE (OBPM 20 mmHg systolic or 10 mmHg diastolic higher than SBPM or daytime ABPM). SETTING: Patients were recruited at hospital or general practice. PATIENTS: A total of 163 mild-to-moderate essential hypertensive patients with a mean age of 56 years (56% males). RESULTS: At eight blood pressure (BP) measurement occasions, 75% of all patients had a substantial WCE at least once, while 57% had WCH at least once. One-third of the patients consistently had a substantial WCE and 14% consistently had WCH on three or more occasions The magnitude of the WCE was significantly related to the height of blood pressure in treated but not in untreated patients. CONCLUSION: In some patients, WCH or a substantial WCE occurs consistently on multiple OBPM visits. Especially in untreated patients, the magnitude of the WCE varies widely among individuals. These results support the incorporation of SBPM and/or ABPM into optimal management of hypertension, not only to prevent misdiagnosis in untreated patients but also to determine the need for adjusting antihypertensive therapy in treated subjects.     

The white-coat effect is associated with increased blood pressure reactivity to physical activity

OBJECTIVE: The aim of this study was to test the hypothesis that blood pressure (BP) reactivity to the stress of a clinic visit, the so-called white-coat effect, is associated with increased BP reactivity to physical activity. DESIGN: Patients referred to our clinic for assessment of hypertension prospectively underwent 24-h ambulatory BP monitoring and simultaneous actigraphy. METHODS: The difference between mean clinic BP and mean daytime ambulatory BP was considered to be a measure of the white-coat effect. Presence or absence of a white-coat effect (clinic-daytime difference > 0 mmHg) was added to a mixed model regression of BP on mean activity score for the 10-min interval preceding BP measurement. RESULTS: The group (n = 421) was heterogeneous in age, gender, mean 24-h BP and use of antihypertensive medications. A total of 259 patients had a systolic white-coat effect; for diastolic BP there were 264. Female patients exhibited a significantly larger white-coat effect. Coefficients for the regressions of both systolic and diastolic blood pressure on physical activity levels were significantly higher in those who had a white-coat effect. CONCLUSIONS: These data suggest increased BP reactivity to activity in those with a white-coat effect. Patients with a prominent white-coat effect may experience greater BP load during normal daily activities as a consequence of increased BP reactivity. In patients with white-coat hypertension, this may contribute to target-organ damage.     

Serum cortisol in the white-coat phenomenon

BACKGROUND: The rise in blood pressure associated with a clinic visit (the white-coat phenomenon) may result from anxiety or an alerting reaction. There is evidence to suggest that glucocorticoids may be involved in the mechanism of stress-related blood pressure elevation, but the relationship between the white-coat phenomenon and glucocorticoids has not been assessed. DESIGN: Forty-eight young subjects with essential hypertension were compared with 12 control normotensive subjects. METHODS: Home blood pressure monitoring for 7 days and serum cortisol at 0900 h and 2 h rest at 1100 h were measured. The white-coat phenomenon was calculated for systolic and diastolic blood pressure and average home blood pressure. RESULTS: The serum cortisol level was significantly greater at 0900 h than that at 1100 h in the hypertensive subjects and was higher in the hypertensive subjects than in the normotensive subjects (21.5 +/- 0.5 versus 14.3 +/- 0.9 μg/dl), but there was no difference between serum cortisol levels at 1100 h in the two groups. The magnitude of the white-coat phenomenon, which was greater in the hypertensive subjects than in the normotensive group (22 +/- 2/12 +/- 1 versus 4 +/- 3/1 +/- 3 mmHg), correlated with serum cortisol at 0900 h, but not at 1100 h. The higher level of serum cortisol at 0900 h was confirmed by another measurement conducted 4 months later in a subsample of the hypertensive subjects ( n = 18). CONCLUSIONS: These results suggest that the white-coat phenomenon is related to the transient increase in serum cortisol or psychological stress, or both, which can trigger arousal of the hypothalamic pituitary adrenocortical axis.