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In patients with mild hypertension the decision to treat is an important issue that has again come to the fore with the availability of several new techniques for measuring blood pressure. The rise in blood pressure induced by the act of measurement itself, referred to as the "white coat reaction," may lead to a false diagnosis of hypertension. This is one reason why 40% of the patients included in large scale hypertension trials subsequently became normotensive with placebo.[2,3]
The guidelines from the World Health Organisation-International Society of Hypertension (ISH) take this into account and recommend multiple mesurements over six months before treatment is started. The basis for such a policy is, firstly, that multiple measurements may be expected to give a closer estimation of the true blood pressure and, secondly, that repetition of measures over time may decrease the reaction induced by the visit to the doctor. This protocol is presently the gold standard for the decision to treat mild hypertension because epidemiological data, classification of hypertension, and evaluation of treatment efficacy are all based on clinic readings and because the white coat reaction has been shown to diminish considerably after four months. This protocol, however, is tedious, risks losing patients to follow up, and the extent of its correct use by general practitioners is unknown. Consequently, it may prove to be less useful than expected when applied in reality.
Ambulatory blood pressure monitoring is a widely accepted method of measuring blood pressure, which avoids the white coat reaction' and becomes increasingly acceptable to patients as the equipment gets smaller. The value of a single ambulatory record in predicting the need for treatment has never been compared with that of a reference method. We assessed the predictive value of one 12 hour ambulatory blood pressure record for the decision to treat patients with mild hypertension by comparing it with the decision made during the six months' follow up in the clinic, according to the WHO-ISH protocol.
Patients and methods
A total of 154 men and women who were referred to the hypertension clinic of the Broussais University Hospital for evaluation of their hypertension were screened for inclusion in the present study. The inclusion criteria were (a) casual diastolic blood pressure between 90 and 110 mm Hg; (b) absence of symptomatic cardiovascular disease; (c) absence of secondary hypertension; and (d) willingness to participate in the study. Patients already taking drugs for hypertension were not necessarily excluded. Those patients in whom the indication for pharmaceutical treatment was questionable were considered for the inclusion after at least a 15 day wash out period.
Each patient fulfilling the inclusion criteria was referred at least two weeks after the screening visit to the physician in charge of the study. Patients were included if their casual blood pressure without treatment remained in the 90-104 mm Hg range at this consultation. The 12 hour ambulatory recording was performed after this visit with the Spacelabs 5200 monitor. Each patient then attended four additional visits at the outpatient clinic over six months. The ambulatory monitoring results were not made available to the physician in charge of the patients until the end of the study. The decision to treat was based on diastolic blood pressure figures obtained at the clinic according to the WHO-ISH guidelines (diastolic blood pressure > 100 mm Hg at the third and fourth visit and > 9 5 mm Hg at the fifth visit).
The decision made by the physician was then compared retrospectively with the decision that would have been from the ambulatory recording alone. Patients were arbitrarily classified as …