Along with ambulatory blood pressure, home blood pressure monitoring is an approach capable of providing information on the behaviour of this haemodynamic variable outside the clinical ward, thereby overcoming many limitations of sphygmomanometric (or clinic) blood pressure measurements.
This paper will highlight the main elements of novelty of the new Guidelines for blood pressure monitoring at home, issued by an “ad-hoc” Committee of the European Society of Hypertension (1).
1 - “True” blood pressure values
Self-measurement of blood pressure at home provides information regarding the “true” blood pressure values (i.e. values free of a significant “white-coat” effect) of a given patient. The procedure therefore allows us to overcome a major limitation of clinic blood pressure measurement, i.e. its dependence on the so-called “alarm reaction” which artefactually increases blood pressure values and may act as a confounder in the diagnosis of hypertension (2).
Home blood pressure, although unable to provide the large amount of information on daily live blood pressure guaranteed by ambulatory blood pressure monitoring, allows us to obtain information on blood pressure behaviour in daily life of major clinical and therapeutic relevance.
2 - Shared advantages of home blood pressure measurements and ambulatory blood pressure measurements.
Along with the lack of any significant “white-coat” effect, home blood pressure shares some of the advantages of ambulatory blood pressure, regarded by experts as the “gold standard” approach in the field. These include:
- the elevated reproducibility of the data acquired,
- the ability of the approach to predict the presence and progression of organ damage as well as the risk of cardiovascular events better than office values,
- the limited economic burden and
- the possibility to improve patient’s compliance to treatment and blood pressure control (1).
3 – Studies evaluating the predictive information on cardiovascular morbidity and mortality of home blood pressure measurements.
The ability of the approach to provide predictive information on cardiovascular morbility and mortality has been investigated in about 15 prospective studies carried out in the past few years. The results of these studies can be summarized as follows.
First, home blood pressure is more closely associated with the risk of cardiovascular events than clinic blood pressure in a wide range of subjects’ age (3-4).
Second, this asspciation does also occur in elderly people and is present regardless the low or the high number of blood pressure evaluations on which home blood pressure is based (1-5).
Third, the predictive value of home blood pressure involves also the progression of renal failure in patients with chronic kidney disease or the morbility and mortality related to stroke and to acute coronary heart events (1).
Finally, evidence has been provided that home blood pressure values may predict better than clinic blood pressure in presence of metabolic abnormalities (particularly those affecting glucose and lipid profile) as well as of target organ damage (6-7).
In the Pressioni Arteriose Monitorate E Loro Associazioni (PAMELA) study we found that home blood pressure carries a predictive power of detecting left ventricular hypertrophy as well as mayor dysmetabolic alterations, such as prediabetes, diabetes as well as metabolic syndrome (6-7).
Guidelines on home blood pressure monitoring address two further methodological issues related to this procedure (1). They indeed recognize some limitations of the approach, such as:
- lack of nighttime blood pressure measurement,
- the difficulties to obtain accurate and technically valid blood pressure evaluation, particularly in aged individuals and
- the chance to induce anxiety for blood measurement in the patients and thus the possibility that the patient modifies the therapeutic approach independently on the doctor’s advice. Finally, doctors (and patients) should keep clearly in mind that normality values are lower than the sphygmomanometric ones and slightly higher than ambulatory blood pressure values (Table 1).
- Indications for Home Blood Pressure monitoring.
A number of clinical conditions may take benefit from the use of home blood pressure (1). These include, for example, the assessment of “isolated office” or “white coat” hypertension, i.e. a condition detectable in about 15% of the general population and characterized by a persistent elevation in office blood pressure while home blood pressure (or 24 hour ambulatory blood pressure) is perfectly normal(8). These may also include the reverse phenomenon, i.e. “masked hypertension”, known as the condition characterized by an elevated ambulatory or home blood pressure and normal clinic blood pressure (8).
Another compelling indication of the approach is represented by the evaluation of antihypertensive drug treatment, particularly in the difficult task to identify “true” resistant hypertensive patients (9).
Finally, home blood pressure monitoring may be indicated to improve patient’s compliance to treatment as well as blood pressure control. This latter objective of the approach has a major clinical relevance, taking into account that a consistent faction of the treated hypertensive patients display a poor blood pressure control, and that this is particularly the case in high or very high risk individuals (9).
5 - Unsolved Issue Related To Home Blood Pressure Monitoring.
The Guidelines document also highlights another still unsolved issue related to the use of home blood pressure (1). These include the use of the approach in special populations, such as children, adolescents, elderly, pregnant women, obese patients, in which the lack of reference values for normality and/or technical difficulties in obtaining blood pressure measurements may make more difficult the use of this approach in the above mentioned conditions. This is also the case for cardiac arrhythmias (particularly atrial fibrillation) due to fact that the accuracy of the blood pressure measurement is lost or heavily impaired when an irregular or a chaotic cardiac rhythm is present.
Table 1 : Blood Pressure normality values for office, home and 24 hour ambulatory blood pressure according to ESH/ESC Guidelines (9),
|Office or clinic||140||90|
Home Blood Pressure: Practical Recommendations
The European Society of Hypertension / European Society of Cardiology Guidelines for the management of hypertension emphasize, in the document issued in 2007, some practical recommendations. These recommendations, which are also present in the home blood pressure monitoring document (1), can be schematically summarized as follows:
- Recommend use of validated equipments.
- Prefer semiautomatic rather than mercury sphygmomanometric devices.
- Recommend that patients obtain blood pressure measurements in the sitting position.
- Do not request an excessive number of measurements during the daytime, but rather look for two blood pressure measurements (morning and evening), possibly before the drugs administration.
- Recommend to the patient accurate transcription of the time of the blood pressure reading as well as of the blood pressure values.
- Consider that, as for ambulatory blood pressure normality, values are lower than office blood pressure.
The content of this article reflects the personal opinion of the author/s and is not necessarily the official position of the European Society of Cardiology.