2.1 Detection of hypertension

Routine blood pressure measurement is of value in detecting hypertension and also provides a useful record of baseline blood pressure in normotensive patients. As hypertension occurs commonly and is often asymptomatic, a proactive strategy is required to ensure its detection at a community level. There is a lack of data regarding the process of detection of hypertension in older people, but in younger patients this has been achieved using different practice-based strategies.^{35, 36, 37, 38, 39, 40}

Case finding is one approach, where hypertension is detected when the patient rather than the doctor initiates the consultation. Blood pressure checks may be done during any consultations but are particularly suitable for inclusion in new patient examinations.

For patients over the age of 75, a blood pressure check should be performed in those who attend for their annual health care check.

Practices should also have a strategy for case finding in the 60-75 year age group.

Case finding should be considered as an ongoing process where blood pressure measurements are performed in the target population at regular intervals. Follow up recordings are required to establish a diagnosis of hypertension following an initial high reading (see section 2.3). Audit is an important element of any case finding strategy.

2.2 Measurement of blood pressure

Before blood pressure measurements are taken there is a need for patients to understand the potential benefits and implications of treating hypertension. Blood pressure control should form part of a cardiovascular risk reduction strategy. Lifestyle changes should be emphasised and other risk factors addressed.

Detailed advice on the measurement of blood pressure has been published by the British Hypertension Society.⁴¹ An updated version on CD-ROM has been published by the BMJ in 1999 and is recommended for consultation by all health professionals involved in hypertension management. A video is also available (see Annex 3).

Blood pressure measurement is critical to the management of hypertension. Validated equipment should be used and the recommendations of the British Hypertension Society on blood pressure measurement should be followed. Evidence level IV

Important points to be considered in recording the patient's blood pressure are noted in Table 3. In practice it may not be possible to meet the ideal conditions described in all circumstances.

Table 3

Important points in recording blood pressure

2.2.1 Home and ambulatory blood pressure recording

Home blood pressure checking may improve the effectiveness of management and can help check compliance/concordance. Ambulatory blood pressure monitoring has also proved useful in certain circumstances, for example in borderline situations, in suspected "white coat" hypertension (patients whose blood pressure is consistently elevated in the GP surgery or the hospital clinic but normal at other times), and in apparent refractory hypertension. The British Hypertension Society also recommends use of ABPM when clinic blood pressure shows unusual variability and when symptoms suggest the possibility of hypotension.²¹

There are limited data available about the prognostic value of home and ambulatory blood pressure monitoring devices: further studies are required to clarify their role in the management of blood pressure problems and the recommendations of a BHS working party are awaited and will be considered on review of this guideline.

It should be noted that the normal range for blood pressure levels when using home and ambulatory BP monitoring devices is set lower than surgery recording. It is likely that the upper limit of normal is around 135/85 mm Hg for home and ambulatory blood pressure monitoring.^{42, 43} The results of longitudinal studies are awaited.

The normal range for home blood pressure measurements and ambulatory blood pressure monitoring is lower than "normal" surgery or clinic values.

2.3 Diagnosis of hypertension

This requires careful consideration and requires at least three repeated blood pressure measurements over a period varying from days to months. The frequency of visits will be dictated by the severity of hypertension and co-morbidity. Clearly those at highest risk will require more rapid assessment to confirm the diagnosis, facilitate investigation and commence treatment.

Recommendations for review following initial blood pressure measurement to facilitate the diagnosis of hypertension adapted from JNC-VI¹⁹ are shown in Table 4. Anyone who has a high reading on one or more occasion should have their blood pressure re-measured at least annually.

The average of three blood pressure readings should be taken as the baseline blood pressure.

Table 4

Recommendations for review following initial blood pressure measurement (adapted from JNC-VI¹⁹)

* If systolic and diastolic categories are different, follow recommendations for shorter review period.
** Modify review period according to reliable information about past blood pressure measurements, other cardiovascular risk factors, or target organ disease.