George S. Stergiou

Reproducibility of home and ambulatory blood pressure in children and adolescents.

ObjectiveTo evaluate the reproducibility of blood pressure measured at home (HBP) in comparison with ambulatory (ABP) and clinic blood pressure (CBP) in children and adolescents. Participants and methodsIndividuals aged 8–17 years who had been referred for elevated CBP were included. CBP was measured at two visits, HBP on 5 days and ABP for 24u2009h. A second session including all the above measurements was performed after 8 weeks. The reproducibility of CBP (second visit of each session), HBP (average of days 2–5 of each session) and ABP (average 24-h, awake and asleep) was quantified using test–retest correlations coefficients (r) and the standard deviation of differences (SDD) between repeated measurements. ResultsSixteen individuals were included [mean age 13.3±2.9 (SD)] years, range 8–17, nine boys]. According to Task Force CBP criteria, eight were classified as hypertensives, three as high normal and five as normotensives. The reproducibility of HBP (systolic/diastolic r, 0.74/0.82, SDD 7.0/4.3) was superior to that of CBP (r, 0.63/0.80, SDD 10.4/6.3). However, ABP appeared to provide the most reproducible values (r, 0.87/0.84, SDD 5.5/4.3 for 24-h ABP; r, 0.85/0.76, SDD 5.9/5.0 for awake; r, 0.76/0.79, SDD 7.0/5.0 for asleep ABP). Aspects of the diurnal ABP variation were poorly reproducible (r, 0.62/0.14, SDD 6.8/5.5 for awake-asleep ABP difference; r, 0.55/0.26, SDD 0.07/0.11 for awakeu2009:u2009asleep ratio). ConclusionThese data suggest that in children and adolescents home blood pressure measurements are more reproducible than clinic measurements. However, 24-h ambulatory monitoring appears to provide the most reproducible blood pressure values.

Self measured and ambulatory blood pressure in assessing the ‘white-coat’ phenomenon

Ambulatory blood pressure monitoring (ABPM) and self blood pressure monitoring (SBPM) at home offer clear advantages compared to conventional office blood pressure readings [4–17], at least when accurately validated devices are used [18,19] and appropriate reference values are considered [20–22]. These advantages include not only avoidance of the alerting reaction associated with a ‘white coat effect’, but also a higher reproducibility of the average blood pressure values recorded, the lack of a significant placebo effect, the possibility to monitor blood pressure repeatedly over time, the collection of ‘objective’ measurements, free from digit preference and observer bias, and a better prediction of outcome compared to ‘casual’ office blood pressure readings. In particular, SBPM at home offers the possibility of obtaining repeated measurements at different times of the day for several days, weeks, months and even years, which may allow a multiple daily assessment of the blood pressure effects of treatment over a wide time interval. The higher reproducibility of the average values derived from repeated SBPM also carries practical advantages when calculating the sample size of a trial, allowing for a lower number of subjects to be recruited. Such detailed and robust information can be obtained at a lower cost compared to ABPM, and its handling is now made much easier by recent technological progress in data storage, data printing and data tele-transmission [4]. Among these advantages, the possibility offered by both ABPM and SBPM for obtaining blood pressure measurements free from interference by the white coat effect has probably been the most important reason for their progressively increasing clinical use. This feature has also led to the proposal of considering the difference between office and either home blood pressure or daytime average ABP as surrogate [23] measures of the ‘white-coat effect’ [24]. Because of its simple implementation, such an indirect approach has been employed in several studies assessing the frequency and/or the clinical relevance of the white-coat phenomenon. This approach is still being proposed despite recent evidence indicating that the surrogate quantification of the ‘white-coat effect’ derived from the difference between clinic and home or daytime average blood pressure values is unable to faithfully reflect the ‘real’ white-coat effect, as directly assessed through continuous blood pressure recordings obtained immediately before and during the physician’s visit [25–29].

White-coat hypertension and masked hypertension in children.

The use of ambulatory blood pressure monitoring in addition to the conventional office measurements makes possible the detection of individuals with white-coat hypertension and masked hypertension. In children referred for elevated blood pressure, both these phenomena appear to be common (10-15% for each). In a population of healthy children, white-coat hypertension appears to be as common as hypertension, whereas masked hypertension appears to be more common than white-coat hypertension or hypertension. In children with persistent white-coat or masked hypertension, assessment of target organ damage by echocardiography is required. Preliminary evidence suggests that, in contrast to white-coat hypertension, which is not associated with target organ damage, masked hypertension in children is associated with increased left ventricular mass. Children with masked hypertension should be followed up and possibly treated for hypertension if the phenomenon persists or there is evidence of target organ damage.

Self blood pressure monitoring at home by wrist devices: a reliable approach?

In this issue of the Journal, Kikuya et al. [1] describe the results obtained by assessing the accuracy of two wrist and two arm cuff devices for self-blood pressure measurement (self-BPM). Factors affecting the accuracy of wrist devices are also addressed. Their ®nal conclusion is that wrist devices are less reliable than arm devices and therefore their use should be discouraged, a conclusion that is of major clinical relevance given the wide adoption of wrist self-BPM devices in clinical practice. In spite of some methodological problems that deserve to be critically discussed, this paper is of particular interest because it focuses attention on a few speci®c aspects often disregarded in the validation of wrist blood pressure measuring devices. Before addressing this issue in detail, however, some more general considerations on wrist blood pressure measurement might be useful to set the scene.

Self blood pressure measurement at home: how many times?

The need for repeated blood pressure measurements Blood pressure in humans is characterized by continuous and pronounced variations over time due to the complex interplay of several different mechanisms [1]. This has led to the recommendation that blood pressure should be repeatedly measured, before taking any diagnostic or therapeutic decision in hypertensive patients. The recent 2003 European Society of Cardiology (ESC) and European Society of Hypertension (ESH) Guidelines for hypertension management [3], emphasized that this recommendation should apply to all available blood pressure monitoring techniques, including ambulatory blood pressure monitoring (ABPM) over 24 h, conventional blood pressure measurements in the physician’s office and self blood pressure monitoring at the patient’s home (HBP). This recommendation has been consistently supported by the evidence that the availability of a large number of blood pressure readings carries important advantages in the clinical management of hypertensive patients, at least when making use of ABPM [4] and when considering blood pressure measurements obtained in the physician’s office or in the clinic [5,6].

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.

The optimal schedule for self-monitoring of blood pressure by patients at home

The optimal schedule for home blood pressure monitoring should represent the usual level of home blood pressure, give a reproducible value, and have prognostic ability. Therefore, outcome studies, as well as short-term trials assessing the reproducibility of home blood pressure, its stability over time and its relationship with ambulatory blood pressure should be taken into account. A review of this evidence suggests that the optimal schedule should be based on 12–14 measurements, and even more measurements up to 25 are desirable. Morning and evening measurements should be obtained, with at least duplicate measurements per occasion. Measurements on the initial day should preferably be discarded.

Masked, white coat and sustained hypertension: comparison of target organ damage and psychometric parameters

Masked hypertension is defined as low clinic and elevated out-of-clinic pressure (blood pressure, BP) assessed either by patients at home or by ambulatory monitoring. This study compared the cardiovascular status and psychometric characteristics of masked, white coat and sustained hypertensives. Three groups of consecutive subjects with masked (n=100, age 59±11 years), white coat (n=100, 60±10 years) and sustained hypertension (n=100, 60±11 years) diagnosed by ambulatory BP monitoring were compared. Masked hypertensives had higher educational level, exercised more frequently, received fewer drugs and sensed more responsibilities at work than at home. Their left ventricular hypertrophy indexes fall in-between those with white coat and sustained, the latter having the highest values. The estimated total cardiovascular risk was intermediate between white coat and sustained, whereas their cardiovascular morbidity and renal disease was higher than that of white coat and similar to sustained. Psychological profile analysis showed lower score for type-A personality and their mood behaviour in the hypomania–euthymia range compared with white coat and sustained hypertensives. The cardiovascular risk of masked hypertensives is higher than that of white coat and similar to sustained. Masked hypertensives have higher educational level, better physical training and different personality/mood pattern than white coat and sustained.

Prognostic value of home blood pressure measurement.

Although self-monitoring of blood pressure by patients at home is being widely used in clinical practice, the evidence on its prognostic value is still limited. Five long-term studies with nearly 60u2009000 patients/year have provided prognostic information for home blood pressure measurements. Differences exist among these studies regarding the population characteristics, the sample size and follow-up, the methodology and protocol for office and home blood pressure measurement and the adjustment procedure for other risk factors. All these studies, nevertheless, showed systolic home blood pressure to be a significant predictor of cardiovascular risk, and three of them also showed prognostic value of diastolic home blood pressure. Moreover, the prognostic value of home blood pressure appeared to be consistently superior to that of conventional office measurements. The prognostic significance of the white coat and the masked hypertension phenomena detected by home measurements were investigated in two studies, one in treated hypertensive patients and another in a general population sample. These studies showed that patients with white-coat phenomenon have similar cardiovascular risk as those with low office and home blood pressure, whereas the masked hypertension phenomenon is associated with high risk as in patients with uncontrolled hypertension. In conclusion, the available evidence suggests that home blood pressure has strong prognostic value, which appears to be superior to that of the conventional office measurements. More outcome studies on the prognostic value of home blood pressure, however, are needed.

Office Blood Pressure Measurement With Electronic Devices: Has the Time Come?

A lthough the conventional auscultatory office blood pressure (BP) measurement has been the cornerstone of hypertension management, it has important drawbacks and often does not reflect the individual’s true BP. This is mainly due not only to the white-coat phenomenon but also to the fact that physicians rarely follow the recommended methodology for BP measurement.1 Measurements taken by a nurse provide lower and more reliable BPs than those taken by physicians but again are subject to the drawbacks of the auscultatory technique and the observer bias. An alternative and technologically modern approach is to abandon the auscultatory technique and use validated electronic devices, as currently accepted for ambulatory and home BP monitoring. In this issue of the American Journal of Hypertension, Myers et al.2 showed that office BP taken by an electronic device (BpTRU) is lower than that taken by nurses using mercury devices. The authors suggested that this is probably due to minimization of the white-coat effect, and that this method can replace the conventional office measurement. This information is important and definitely points to the future of office BP measurement. However, the lower BP with the BpTRU approach deserves special attention. This might be attributed either to a systematic underestimation of BP in all subjects or to the elimination of the white-coat effect in some. Unfortunately, this issue remains unresolved since out-of-office BP was not assessed. If the former is true, then new (lower) diagnostic thresholds for this method should be defined. An interesting point in the study by Myers et al.2 is that automated office BP measurements were taken in the absence of the observer. When office BP taken by physicians was compared with that taken by nurses, and by an automated device in the absence of an observer, the automated device gave the lowest average BP.3 However, 15 readings were averaged with the automated device compared to 3 readings with the other methods, which probably contributed considerably to the BP difference.