The relationship between casual and ambulatory blood pressure in essential hypertension: the influence of work, duration of hypertension and antihypertensive treatment.

Casual blood pressure (BP) and ambulatory BP (mean 24-h BP) were determined in 23 untreated patients with essential hypertension and in 11 normotensive healthy control subjects. Mean 24-h BP was significantly lower than casual BP in patients with essential hypertension, but not in control subjects. This was demonstrated in the patients who did not work during the ambulatory BP monitoring and in the patients with newly recognized hypertension, whereas no differences were revealed either in the patients who went to work or had a known duration of hypertension longer than 6 months. The size of the difference between casual BP and mean 24-h BP was unaffected by antihypertensive therapy with metoprolol and also individually reproducible. An accordance between casual and ambulatory BP measurements in evaluation of the efficacy of antihypertensive treatment was found in 75% of the patients. Casual BP and mean 24-h BP were weakly correlated both before and during antihypertensive treatment. It is concluded that the higher casual BP than ambulatory BP in essential hypertension may be a specific characteristic of the disease. Both work and known duration of hypertension longer than 6 months eliminate the difference between casual ambulatory BP in essential hypertension. Ambulatory BP monitoring seems to be superior to casual BP measurements in the evaluation of antihypertensive treatment.