Association between different measurements of blood pressure variability by ABP monitoring and ankle-brachial index.
BACKGROUND
Blood pressure (BP) variability has been associated with cardiovascular outcomes, but there is no consensus about the more effective method to measure it by ambulatory blood pressure monitoring (ABPM). We evaluated the association between three different methods to estimate BP variability by ABPM and the ankle brachial index (ABI).


RESULTS
In a cross-sectional study of patients with hypertension, BP variability was estimated by the time rate index (the first derivative of SBP over time), standard deviation (SD) of 24-hour SBP; and coefficient of variability of 24-hour SBP. ABI was measured with a doppler probe. The sample included 425 patients with a mean age of 57 ± 12 years, being 69.2% women, 26.1% current smokers and 22.1% diabetics. Abnormal ABI (≤ 0.90 or ≥ 1.40) was present in 58 patients. The time rate index was 0.516 ± 0.146 mmHg/min in patients with abnormal ABI versus 0.476 ± 0.124 mmHg/min in patients with normal ABI (P = 0.007). In a logistic regression model the time rate index was associated with ABI, regardless of age (OR = 6.9, 95% CI = 1.1- 42.1; P = 0.04). In a multiple linear regression model, adjusting for age, SBP and diabetes, the time rate index was strongly associated with ABI (P < 0.01). None of the other indexes of BP variability were associated with ABI in univariate and multivariate analyses.


CONCLUSIONS
Time rate index is a sensible method to measure BP variability by ABPM. Its performance for risk stratification of patients with hypertension should be explored in longitudinal studies.
Hospital de Clínicas de Porto Alegre, Brazil.
Estefânia
E
Wittke
Sandra C
SC
Fuchs
Flávio D
FD
Fuchs
Leila B
LB
Moreira
Elton
E
Ferlin
Fábio T
FT
Cichelero
Carolina M
CM
Moreira
Jeruza
J
Neyeloff
Marina B
MB
Moreira
Miguel
M
Gus
D000368:Aged; D055109:Ankle Brachial Index / Q000706:statistics & numerical data*; D001794:Blood Pressure; D018660:Blood Pressure Monitoring, Ambulatory / Q000379:methods; D001938:Brazil; D048909:Diabetes Complications / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D005260:Female; D006801:Humans; D006973:Hypertension / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D012306:Risk; D012907:Smoking