title: Long-term reproducibility of ambulatory blood pressure is superior to office blood pressure in the very elderly.
abstract: Although it is known that reproducibility of ambulatory blood pressure (BP) is superior to office BP in middle-aged subjects, little is known in older age groups. Hence, we compared the long-term reproducibility of ambulatory and office BP readings in subjects over the age of 75 years. A cohort of 72 subjects 75-90 years of age (mean, 82 years at baseline) had repeat office and ambulatory BPs 2 years apart under similar conditions. On the same day, patients underwent office BP measurements by a semi-automated device and then by ambulatory BP monitoring. Awake and sleep periods were divided according to a diary kept by each patient. The agreement between studies was assessed using the standard deviation of the differences (SDD) and Bland-Altman plots. There were minimal mean changes in office, 24-h, and awake and sleep mean BP values between baseline and 2 years later. The SDDs between visits were lower for 24-h BP compared with the office BP (11.7/5.9 mm Hg versus 17.8/9.0 mm Hg, P<0.01). The SDD for 24-h BP was also lower than the SDDs for the awake and sleep BP (P<0.05). Nocturnal BPs defined by absolute values were more reproducible than categories of dippers and non-dippers. These data demonstrate that long-term reproducibility of 24-h BP is superior to office measurements for very elderly subjects. In a clinical trial involving this age group, far fewer subjects would be required if 24-h BP was the primary efficacy endpoint rather than the office BP.
authors.affiliation: Division of Hypertension and Clinical Pharmacology, Calhoun Cardiology Center, University of Connecticut School of Medicine, Farmington, CT, USA.
authors.forename: P
authors.initials: P
authors.lastname: Campbell
authors.forename: N
authors.initials: N
authors.lastname: Ghuman
authors.forename: D
authors.initials: D
authors.lastname: Wakefield
authors.forename: L
authors.initials: L
authors.lastname: Wolfson
authors.forename: W B
authors.initials: WB
authors.lastname: White
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure; D001795:Blood Pressure Determination / Q000379:methods*; D018660:Blood Pressure Monitoring, Ambulatory; D001921:Brain / Q000473:pathology; D002940:Circadian Rhythm; D003071:Cognition; D015331:Cohort Studies; D006299:Health Services for the Aged; D006801:Humans; D008279:Magnetic Resonance Imaging; D009819:Office Visits; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013997:Time Factors