To explore the association of different types of blood pressure (BP) variability measures estimated from either short-term ambulatory reading-to-reading or long-term clinic visit-to-visit BP records with long-term survival in an elderly treated hypertensive population.
A subset of patients (n = 508) aged at least 65-years was studied from the Second Australian National Blood Pressure study. We estimated SBP and DBP BP variability as the SD of ambulatory (24-h, daytime, night-time) and clinic visit-to-visit BP directly from all corresponding on-treatment within-individual BP records. Ambulatory ‘weighted day–night’ variability was calculated as a weighted mean of daytime and night-time SD. Cox-proportional hazard models adjusted for baseline risk factors (Model 1) and corresponding on-treatment BP (Model 2) or average night-time SBP (best predictive BP measure for outcome) (Model 3) were used to determine the relationship between long-term outcome and BP variability.
Over a median of 10.6 years, 101 patients died from any cause, of which 51 deaths were cardiovascular. We observed increase in ‘daytime’ and ‘weighted day–night’ SBP/DBP variability was significantly associated with increased all-cause mortality in all models. For cardiovascular mortality, only ‘weighted day–night’ SBP variability significantly predicted risk in all models (Model 3 hazard ratio: 1.09, 95% confidence interval: 1.00–1.19, P = 0.04). Long-term BP variability was not associated with any outcome. On direct comparison, both ‘daytime’ and ‘weighted day–night’ BP variability measures provided similar prognostic information.
Short-term ‘daytime’ and ‘weighted day–night’ SBP variability from ambulatory BP recordings was a better predictor of mortality in elderly treated hypertensive patients than long-term BP variability from visit-to-visit BP recordings.
aCentre of Cardiovascular Research & Education in Therapeutics, Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria
bDepartment of Clinical Pharmacology, College of Medicine and Public Health, Flinders University, Adelaide, South Australia
cSydney Medical School, University of Sydney, New South Wales
dBaker Heart and Diabetes Institute, Melbourne, Victoria
eSchool of Medicine, University of Western Australia, Royal Perth Hospital
fSchool of Public Health, Curtin University, Perth, Western Australia, Australia
Correspondence to Enayet K. Chowdhury, Department of Epidemiology and Preventive Medicine, Monash University, 6th Floor, Alfred Centre, 99 Commercial Rd, Melbourne, VIC, 3004, Australia. Tel: +61 3 99030524; fax: +61 3 9903 0556; e-mail: firstname.lastname@example.org
Abbreviations: ABPM, ambulatory blood pressure monitoring; AIC, Akaike's Information Criterion; ANBP2, Second Australian National Blood Pressure study; BP, blood pressure
Received 22 June, 2017
Revised 20 October, 2017
Accepted 15 November, 2017
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