title: Is blood pressure during the night more predictive of cardiovascular outcome than during the day?
abstract: The objective of this study was to investigate the prognostic significance of the ambulatory blood pressure (BP) during night and day and of the night-to-day BP ratio (NDR). We studied 7458 participants (mean age 56.8 years; 45.8% women) enrolled in the International Database on Ambulatory BP in relation to Cardiovascular Outcome. Using Cox models, we calculated hazard ratios (HR) adjusted for cohort and cardiovascular risk factors. Over 9.6 years (median), 983 deaths and 943 cardiovascular events occurred. Nighttime BP predicted mortality outcomes (HR, 1.18-1.24; P<0.01) independent of daytime BP. Conversely, daytime systolic (HR, 0.84; P<0.01) and diastolic BP (HR, 0.88; P<0.05) predicted only noncardiovascular mortality after adjustment for nighttime BP. Both daytime BP and nighttime BP consistently predicted all cardiovascular events (HR, 1.11-1.33; P<0.05) and stroke (HR, 1.21-1.47; P<0.01). Daytime BP lost its prognostic significance for cardiovascular events in patients on antihypertensive treatment. Adjusted for the 24-h BP, NDR predicted mortality (P<0.05), but not fatal combined with nonfatal events. Participants with systolic NDR of at least 1 compared with participants with normal NDR (> or = 0.80 to <0.90) were older, at higher risk of death, but died at higher age. The predictive accuracy of the daytime and nighttime BP and the NDR depended on the disease outcome under study. The increased mortality in patients with higher NDR probably indicates reverse causality. Our findings support recording the ambulatory BP during the whole day.
authors.affiliation: Department of Cardiovascular Diseases, Division of Hypertension and Cardiovascular Rehabilitation, Studies Coordinating Centre, University of Leuven, Leuven, Belgium.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: José
authors.initials: J
authors.lastname: Boggia
authors.forename: Lutgarde
authors.initials: L
authors.lastname: Thijs
authors.forename: Tine W
authors.initials: TW
authors.lastname: Hansen
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kikuya
authors.forename: Kristina
authors.initials: K
authors.lastname: Björklund-Bodegård
authors.forename: Tom
authors.initials: T
authors.lastname: Richart
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Ohkubo
authors.forename: Tatiana
authors.initials: T
authors.lastname: Kuznetsova
authors.forename: Christian
authors.initials: C
authors.lastname: Torp-Pedersen
authors.forename: Lars
authors.initials: L
authors.lastname: Lind
authors.forename: Hans
authors.initials: H
authors.lastname: Ibsen
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Imai
authors.forename: Jiguang
authors.initials: J
authors.lastname: Wang
authors.forename: Edgardo
authors.initials: E
authors.lastname: Sandoya
authors.forename: Eoin
authors.initials: E
authors.lastname: O'brien
authors.forename: Jan A
authors.initials: JA
authors.lastname: Staessen
mesh_terms: D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000502:physiology*; D018660:Blood Pressure Monitoring, Ambulatory; D002318:Cardiovascular Diseases / Q000209:etiology / Q000503:physiopathology*; D002940:Circadian Rhythm / Q000502:physiology*; D015331:Cohort Studies; D016208:Databases, Factual; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012307:Risk Factors; D016019:Survival Analysis