Diagnostic value of strategy for the detection of white coat hypertension based on ambulatory and home blood pressure monitoring

Practical Aspects of Home and Ambulatory Blood Pressure Monitoring

Out-of-office blood pressure (BP) monitoring is becoming increasingly important in the diagnosis and management of hypertension. Home BP and ambulatory BP monitoring (ABPM) are the two forms of monitoring BP in the out-of-office environment. Home BP monitoring is easy to perform, inexpensive, and engages patients in the care of their hypertension. Although ABPM is expensive and not widely available, it remains the gold standard for diagnosing hypertension. Observational studies show that both home BP and ABPM are stronger predictors of hypertension-related outcomes than office BP monitoring. There are no clinical trials showing their superiority over office BP monitoring in guiding the treatment of hypertension, but the consistency of observational data make a compelling case for their preferential use in clinical practice.

Home blood pressure monitoring in the diagnosis and treatment of hypertension: a systematic review

BACKGROUND

It is recognized that for the reliable assessment of blood pressure (BP) and the accurate diagnosis of hypertension, out-of-office BP measurement with ambulatory (ABPM) or home BP monitoring (HBPM) is often required. The clinical usefulness of ABPM is well established. However, despite the wide use of HBPM, only in the last decade convincing evidence on its usefulness has accumulated.

METHODS

Systematic review of the evidence on applying HBPM in the diagnosis and treatment of hypertension (PubMed, Cochrane Library, 1970-2010).

RESULTS

Sixteen studies in untreated and treated subjects assessed the diagnostic ability of HBPM by taking ABPM as reference. Seven randomized studies compared HBPM vs. office measurements or ABPM for treatment adjustment, whereas many studies compared HBPM with office measurements in assessing the antihypertensive drug effects. Several studies with different design investigated the role of HBPM vs. office measurements in improving patients' compliance with treatment and hypertension control rates. The evidence on the cost-effectiveness of HBPM is limited. The studies reviewed consistently showed moderate diagnostic agreement between HBPM and ABPM, and superiority of HBPM compared to office measurements in diagnosing uncontrolled hypertension, assessing antihypertensive drug effects and improving patients' compliance and hypertension control. Preliminary evidence suggests that HBPM has the potential for cost savings.

CONCLUSIONS

There is conclusive evidence that HBPM is useful for the initial diagnosis and the long-term follow-up of treated hypertension. These data are useful for the optimal application of HBPM, which is widely used in clinical practice. More studies on the cost-effectiveness of HBPM are needed.

Preventing misdiagnosis of ambulatory hypertension: algorithm using office and home blood pressures

OBJECTIVES

An algorithm for making a differential diagnosis between sustained and white coat hypertension (WCH) has been proposed - patients with office hypertension undergo home blood pressure monitoring (HBPM) and those with normal HBP levels undergo ambulatory blood pressure monitoring (ABPM). We tested whether incorporating an upper office blood pressure (OBP) cut-off in the algorithm, higher than the traditional 140/90 mmHg, reduces the need for HBPM and ABPM.

METHODS

Two hundred twenty-nine normotensive and untreated mildly hypertensive participants (mean age 52.5 +/- 14.6 years, 54% female participants) underwent OBP measurements, HBPM, and 24-h ABPM. Using the algorithm, sensitivity, specificity, and positive and negative predictive values (PPV, NPV) for sustained hypertension and WCH were assessed. We then modified the algorithm utilizing a systolic and diastolic OBP cut-off at a specificity of 95% for ambulatory hypertension - those with office hypertension but OBP levels below the upper cut-off underwent HBPM and subsequent ABPM, if appropriate.

RESULTS

Using the original algorithm, sensitivity and PPV for sustained hypertension were 100% and 93.8%, respectively. Despite a specificity of 44.4%, NPV was 100%. These values correspond to specificity, NPV, sensitivity, and PPV for WCH, respectively. Using the modified algorithm, the diagnostic accuracy for sustained hypertension and WCH did not change. However, far fewer participants needed HBPM (29 vs. 84) and ABPM (8 vs. 15).

CONCLUSION

In this sample, the original and modified algorithms are excellent at diagnosing sustained hypertension and WCH. However, the latter requires far fewer participants to undergo HBPM and ABPM. These findings have important implications for the cost-effective diagnosis of sustained hypertension and WCH.

Role of ambulatory and home blood pressure recording in clinical practice

Because of shortcomings of the office blood pressure (BP) measurement in individuals with hypertension (eg, white coat and masked hypertension effects, terminal digit bias, and large variability in BP among a small number of readings), use of out-of-office blood pressure measurements has become more common in clinical practice. The presence of the syndromes of white-coat and masked hypertension creates the concern that the office BP measurements are not reflective of an individual patient's true BP values. Home (or self) and ambulatory BP assessments have been used in numerous types of clinical trials and have demonstrated their usefulness as reliable research and clinical tools. In this article, we review the recent literature on the benefits and limitations of home (self) and ambulatory monitoring of the BP in clinical practice. In particular, how it relates to the diagnosis of patients with various presentations of hypertension and to cardio-vascular outcomes with long-term follow-ups of population cohorts.

Detecting white coat and reverse white coat effects in clinic settings using measures of blood pressure habituation in the clinic and patient self-monitoring of blood pressure

To examine the utility of blood pressure (BP) habituation within and across multiple clinic visits and patient-determined home BP monitoring for detecting white coat (WCE) and reverse white coat effects (RWCE) commonly observed in medical settings, 54 patients undergoing evaluation for hypertension in an internal medicine group practice were categorized according to the magnitude of differences between systolic BP (SBP) and diastolic BP (DBP) obtained in the clinic and through ambulatory BP monitoring. BPs were measured four times during three separate clinic visits, during a 1-week home BP monitoring period, and during a single 24-h ambulatory monitoring period. Patients whose mean clinic and average daytime BPs were within +/-5 mm Hg were categorized as having stable BP; patients whose clinic BPs were >5 mm Hg of their daytime BPs were categorized as showing a WCE and patients whose average daytime BPs were >5 mm Hg of their clinic BPs were categorized as showing a RWCE. Results revealed that degree of habituation occurring between the first and third clinic visits significantly predicted magnitude of both the WCE and RWCE for SBP, with greater habituation being associated with the WCE and lesser habituation associated with the RWCE. Greater SBP habituation within clinic visits was associated with the WCE for SBP and greater DBP habituation within clinic visits was associated with the WCE for DBP. Lesser DBP habituation within clinic visits was associated with the RWCE for both SBP and DBP. Home BP monitoring did not contribute to predicting either WCE or RWCE.

[Home blood pressure self-monitoring. Influence of the mean calculation used on the diagnosis of white-coat hypertension]

OBJECTIVE

To describe the variations in the diagnosis performance of home blood pressure self-monitoring (hBPSM) with different methods for mean calculation, in order to diagnose white-coat hypertension (WCH).

DESIGN

Multi-centre, descriptive, and comparative study to assess the diagnosis performance of a test method.

SETTING

Four primary health care centres.

PARTICIPANTS

A total of 157 recently-diagnosed, untreated patients with mild-moderate hypertension took part in the study.

METHODS

The results obtained with hBPSM (3 consecutive days with readings in triplicate, morning-night) were compared with a "gold standard" out-patient blood pressure reading (OutBP).

RESULTS

Systolic and diastolic BP values of the first day and first reading (morning-night) were higher than the remaining days and readings (linear trend P< .001). Results in hBPSM diagnostic performance using all readings to calculate the mean were: sensitivity (S), 47.6%; specificity (Sp), 77.4%; positive and negative predictive values (PPV and NPV), 58.8% and 68.6%, with positive and negative probability coefficients (PPC and NPC), 2.10 and 0.67. When readings with greater patient alarm reaction (first day and first reading, morning-night) were removed, greater values of S (61.9%) were obtained, albeit at expense of an excessive loss in Sp (64.5%) and without improvement in PPC (1.74).

CONCLUSIONS

The diagnostic performance of hBPSM in WCH was low and failed to improve with the use of different systems to calculate mean BP.

Home blood pressure self-monitoring: diagnostic performance in white-coat hypertension

OBJECTIVE

To determine the diagnostic performance of home blood pressure self-monitoring in white-coat hypertension using a 3-day reading program.

MATERIAL AND METHODS

One hundred and ninety nontreated patients recently diagnosed with mild-moderate hypertension, selected consecutively at four primary healthcare centers in the city of Barcelona, were included. Each patient underwent morning and night home blood pressure self-monitoring with readings in triplicate for three consecutive days, followed by 24-h ambulatory blood pressure monitoring. The normality cut-off point value for home blood pressure self-monitoring and daytime ambulatory blood pressure monitoring was 135/85 mmHg.

RESULTS

Sixty-three patients were diagnosed with white-coat hypertension with home blood pressure self-monitoring (34.8%; 95% confidence interval: 27.9-42.2) and 74 with ambulatory blood pressure monitoring (41.6%; 95% confidence interval: 33.7-48.4). No statistically significant differences were observed between home blood pressure self-monitoring values and those of diurnal ambulatory blood pressure monitoring [137.4 (14.3)/82.1 (8.3) mmHg vs. 134.8 (11.3)/81.3 (9.5) mmHg]. Home blood pressure self-monitoring diagnostic performance parameters were sensitivity 50.0% (95% confidence interval: 38.3-61.7), specificity 75.7% (95% confidence interval: 66.3-83.2), positive and negative predictive values 58.7% (95% confidence interval: 45.6-70.8) and 68.6% (95% confidence interval: 59.4-76.7), respectively, and positive and negative probability coefficients 2.05 and 0.66, respectively. Analysis of different normality cut-off points using a receiver operating characteristic curve failed to produce significant improvement in the diagnostic performance of home blood pressure self-monitoring.

CONCLUSIONS

The diagnostic accuracy of a 3-day home blood pressure self-monitoring reading program in white-coat hypertension was poor. Ambulatory blood pressure monitoring continues to be the test of choice for this indication.

Prevalence and determinants of isolated clinic hypertension in the Finnish population: the Finn-HOME study

BACKGROUND

Previous studies performed in selected hypertensive subjects have reported several possible determinants of isolated clinic hypertension (ICH). The purpose of this study was to assess the prevalence and determinants of ICH in a randomly selected nationwide population.

METHODS

We studied a representative sample of the general adult population (1440 45-74-year-old subjects) in Finland not treated for hypertension. The subjects were drawn from the participants of a multidisciplinary epidemiological survey, the Health 2000 Study. Subjects included in the study underwent a clinical interview, determination of serum lipids and glucose, measurement of clinic and home blood pressure (BP), and psychometric tests for psychological distress, hypochondriasis, depression, and alexithymia. The diagnosis of ICH was based on a clinic BP of 140/90 mmHg or greater and a home BP less than 135/85 mmHg.

RESULTS

The prevalence of ICH in the untreated Finnish adult population was 15.6 and 37.5% among untreated clinic hypertensive individuals. In a multivariate logistic regression analysis, ICH was associated with mildly elevated systolic and diastolic BP, lower body mass index (BMI), and non-smoking status. Subjects with ICH represent an intermediate group between the normotensive and sustained hypertensive individuals where cardiovascular risk is concerned (age, BP, diabetes prevalence, lipid profile, and BMI).

CONCLUSION

ICH is a common phenomenon in the general population. Non-smoking individuals with mildly elevated BP and low BMI have a higher risk of ICH. Physicians should disassociate the diagnosis of ICH from any psychosocial disorders, but should remember that patients with ICH have an increased risk of cardiovascular disease.

Use of home blood-pressure monitoring in the detection, treatment and surveillance of hypertension

PURPOSE OF REVIEW

Use of home blood-pressure monitoring is increasing but the technique and the equipment have limitations. We provide an overview of recent evidence in this rapidly evolving field.

RECENT FINDINGS

Home blood-pressure monitoring is an acceptable method for screening patients for hypertension. There is increasing evidence supporting the predictive power of home blood pressure for stroke risk even in the general population. The identification of white-coat and masked hypertension remains an important role for home blood-pressure monitoring. Unvalidated equipment and poor patient technique are major concerns. The purchase of devices needs to be linked to a simple patient-education programme, which is perhaps an opportunity for collaboration between healthcare providers and commercial companies. Devices that store the blood-pressure measurements in the memory are preferred to ensure accuracy of reporting. Data-transmission systems providing automatic storage, transmission and reporting of blood pressure, direct involvement of the patient and potentially a reduced number of hospital/general practitioner visits, offer significant advantages. To reduce patient anxiety, overuse of home blood-pressure monitoring should be avoided but there is the potential for self-modification of treatment, subject to certain safeguards.

SUMMARY

Self-monitoring of blood pressure is developing rapidly, linked to increasing awareness of the impact of reducing high blood pressure on public health and the marketing/advertising strategies used to sell automatic devices. Home blood-pressure monitoring has a role in the detection and management of blood pressure, but not at the expense of careful blood-pressure measurement in the office and adherence to national guidelines.

Self-measurement of blood pressure at home in the management of hypertension

To be suitable for the management of hypertension, self-measurement of blood pressure (BP) at home should follow international recommendations. The use of accurate and validated measuring devices is an important prerequisite. Upper arm BP monitors are the first choice, while wrist and finger devices cannot be recommended. Measurements should, preferentially, be downloaded from the memory of a device or printed. Reference values have been proposed, but were mostly based on cross-sectional observations and have not yet been widely validated by prospective outcome studies. Currently, levels of home BP of <135 mm Hg systolic and 85 mm Hg diastolic are usually considered normal. Home BP measurement is sometimes recommended as an alternative to ambulatory BP monitoring to diagnose white-coat hypertension.However, home BP measurement cannot replace ambulatory BP monitoring in the diagnosis of hypertension (white-coat), but both techniques have complementary roles. The appropriateness of home BP measurement to guide antihypertensive treatment has only been tested in one large-scale randomized trial: the THOP (Treatment of Hypertension Based on Home or Office Blood Pressure) trial. The THOP trial showed that antihypertensive treatment based on home instead of office BP led to less intensive drug treatment, but also to less BP control with no differences in general wellbeing and left ventricular mass. Home BP monitoring also contributed to the identification of patients with white-coat hypertension. On balance, most evidence supports the view that office BP measurement remains the key in the diagnosis and treatment of hypertension. Treatment can be started without confirmation of elevated office BP in patients with high office BP and target organ damage, or a high cardiovascular risk profile. In patients with raised office BP but without target organ damage (white-coat hypertension), or with normal office BP but unexplained target organ damage (masked hypertension), ambulatory or home BP monitoring or both must be used to confirm the diagnosis. Few longitudinal studies have addressed the long-term prognostic meaning of home BP measurement. Until more prospective data become available, management of hypertension exclusively based on self-measurement of BP at home cannot be recommended.

New European, American and International guidelines for hypertension management: agreement and disagreement

Hypertension is a leading cause of morbidity and mortality worldwide and its control rates remain poor. In 2003, several official organizations presented new guidelines for hypertension management. These guidelines were developed using an evidence-based interpretation of the available information. Recommendations on hypertension prevention, diagnosis, patients' evaluation, decision to treat, antihypertensive drug selection and goals of treatment are included. There is considerable agreement among the new guidelines and only a few points of disagreement, that are of minor significance. Emphasis has been placed on the simplicity of recommendations in order for them to be easily applied by primary care physicians. This review focuses on the key messages of the 2003 guidelines and the areas of agreement and disagreement among them.

White-coat hypertension: a clinical review

White-coat hypertension (WCHT), also called 'isolated office or clinic hypertension', is defined as the occurrence of blood pressure (BP) values higher than normal when measured in the medical environment, but within the normal range during daily life, usually defined as average daytime ambulatory BP (ABP) or home BP values (<135 mm Hg systolic and <85 mm Hg diastolic). The prevalence of WCHT varies from 15% to over 50% of all patients with mildly elevated office BP (OBP) values. In untreated hypertensive patients, the probability of WCHT especially increases with female gender and a mildly elevated OBP level. The value of other possible determinants such as (non) smoking status, duration of hypertension, left ventricular mass, number of OBP measurements, educational level, etc. is less consistently shown. Although, for various reasons, studies evaluating the long-term effects of WCHT are not always easy to interpret, most data indicate that persons with WCHT have a worse or equal cardiovascular prognosis than normotensives, but a better one than those with sustained hypertension. WCHT is sometimes considered a prehypertensive state, but data on the long-term evolution of subjects with WCHT are scarce. Patients with WCHT and a high cardiovascular risk or proven target organ damage should be pharmacologically treated. Subjects with uncomplicated WCHT should probably not receive medical therapy, but a close follow-up, including regular assessment of other risk factors and measurement of OBP (every 6 months) and ABP (every 1 or 2 years), is warranted.