In their review of the use of evidence in hypertension guidelines, Parker and Glasziou point out that failure to measure blood pressure in both arms may lead to delay in diagnosis or inadequate treatment of high blood pressure.1 However, only 30% of GPs agree with recommendations to measure blood pressure in both arms, and even fewer actually do it. Similarly, it is important to see if patients who take their own blood pressure at home adhere to recommendations, both measuring and recording their readings correctly.
Assessing the reliability of patients' reports of home blood pressure measurements is crucial to see whether self-monitoring can be used by health professionals to provide precise estimates of the true blood pressure.2 Possible disadvantages of this technique include reporting bias and unsupervised alteration of medication. Newer blood pressure monitors offer the advantages of built-in printers or internal storage of all blood pressure measurements, which can be subsequently downloaded.3
We are completing recruitment for a Stroke Association funded trial of home blood pressure monitoring in 360 hypertensive stroke patients.4
Intervention patients are given a blood pressure monitor, shown how to use it, and asked to record their blood pressure once a week taking three readings each time. In Spring 2009 we conducted a pilot study to examine the reliability and accuracy of patients' blood pressure recordings and the degree to which patients might selectively record readings, therefore misreporting their blood pressure. We compared the actual readings downloaded from the blood pressure monitor with those recorded in the patient booklet over the previous month.
We found that most patients were recording their blood pressure accurately, and the measurements recorded were true readings. Although participants may be taking extra readings when their blood pressure was above target, there appeared to be little selectivity in the recording of blood pressure measurements. This is in line with a previous UK study from primary care.5 It suggests that stroke patients who are shown how to monitor their own blood pressure at home generally do it reliably and according to guidelines, an example that GPs who only ever take blood pressure in one arm might consider following!
REFERENCES
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