AMBULATORY MONITORING makes it possible to record blood pressure (BP) throughout the day while subjects engage in their routine activities. In comparison with conventional BP measurements, automated recordings are devoid of digit preference and observer bias and minimize the white-coat effect.1 As a consequence of these advantages and the large number of measurements, a single ambulatory BP recording provides a reliable estimate of a person's BP. To gain equivalent information, conventional BP readings must be standardized and repeated at frequent intervals.2 Furthermore, several studies support the hypothesis that ambulatory BP, in comparison with conventional BP, is better correlated with hypertensive target organ damage, such as left ventricular hypertrophy, [3][4][5]
ContextThe clinical use of ambulatory blood pressure (BP) monitoring requires further validation in prospective outcome studies.Objective To compare the prognostic significance of conventional and ambulatory BP measurement in older patients with isolated systolic hypertension.Design Substudy to the double-blind placebo-controlled Systolic Hypertension in Europe (Syst-Eur) Trial, started in October 1988 with follow up to February 1999. The conventional BP at randomization was the mean of 6 readings (2 measurements in the sitting position at 3 visits 1 month apart). The baseline ambulatory BP was recorded with a noninvasive intermittent technique.Setting Family practices and outpatient clinics at primary and secondary referral hospitals.Participants A total of 808 older (aged Ն60 years) patients whose untreated BP level on conventional measurement at baseline was 160 to 219 mm Hg systolic and less than 95 mm Hg diastolic.Interventions For the overall study, patients were randomized to nitrendipine (n = 415; 10-40 mg/d) with the possible addition of enalapril (5-20 mg/d) and/or hydrochlorothiazide (12.5-25.0 mg/d) or to matching placebos (n = 393).
Main Outcome MeasuresTotal and cardiovascular mortality, all cardiovascular end points, fatal and nonfatal stroke, and fatal and nonfatal cardiac end points.Results After adjusting for sex, age, previous cardiovascular complications, smoking, and residence in western Europe, a 10-mm Hg higher conventional systolic BP at randomization was not associated with a worse prognosis, whereas in the placebo group, a 10-mm Hg higher 24-hour BP was associated with an increased relative hazard rate (HR) of most outcome measures (eg, HR, 1.23 [95% confidence interval {CI}, 1.00-1.50] for total mortality and 1.34 [95% CI, 1.03-1.75] for cardiovascular mortality). In the placebo group, the nighttime systolic BP (12 AM-6 AM) more accurately predicted end points than the daytime level. Cardiovascular risk increased with a higher night-to-day ratio of systolic BP independent of the 24-hour BP (10% increase in night-to-day ratio; HR for all cardiovascular end points, 1.41; 95% CI, 1.03-1.94). At randomization, the cardiovascular risk conferred by a conventional systolic BP of 160 mm Hg was similar to that associated with a...
