Use of home blood pressure measurements to diagnose "white coat hypertension' in general practice.

Mercury sphygmomanometers are the gold standard in blood pressure (BP) measurement. However, white coat hypertension can only be diagnosed by using either continuous ambulatory monitoring or home BP recording. Between 10% and 20% of patients under treatment for hypertension have white coat hypertension and most do not need medication. There have been no reports from general practice in the UK of the use of home recording which seems well suited to it. The aim of this study was to confirm the feasibility of carrying out validation procedures of a UA751 semi-automatic sphygmomanometer and to use it to diagnose white coat hypertension in one practice. Firstly, the validation consisted of tests based on the British Hypertension Societies (BHS) published methods. Simultaneous BP measurements were made with the UA751 and a mercury sphygmomanometer, using a t-tube, of 45 random normotensive and hypertensive patients. Validation readings were mercury instrument means 155/83 (s.d.s 25 and 11), UA751 means 156/85 (s.d.s 25 and 10). The proportion of acceptable differences between the readings placed the UA751 in the BHS Guidelines Grade 'B'. Secondly, to detect white coat hypertension, 52 consecutive new or poorly controlled hypertensive patients took a series of home BP readings. Five patients with white coat hypertension were found. We concluded that it is feasible to use the UA751 to diagnose white coat hypertension in general practice where most hypertensive patients are exclusively managed. Used for this specific purpose, it would be extremely cost effective, precluding many patients from unnecessary medication and saving substantial costs in drugs and other resources.