Relationship between clinic and ambulatory blood pressure and mortality: an observational cohort study in 59 124 patients

Ambulatory blood pressure provides a more comprehensive assessment than clinic blood pressure, and has been reported to better predict health outcomes than clinic or home pressure. We aimed to examine associations of clinic and 24-h ambulatory blood pressure with all-cause and cardiovascular mortality in a large cohort of primary care patients referred for assessment of hypertension.

We did an observational cohort study using clinic and ambulatory blood pressure data obtained from March 1, 2004, to Dec 31, 2014, from the Spanish Ambulatory Blood Pressure Registry. This registry included patients from 223 primary care centres from the Spanish National Health System in all 17 regions of Spain. Mortality data (date and cause) were ascertained by a computerised search of the vital registry of the Spanish National Institute of Statistics. Complete data were available for age, sex, all blood pressure measures, and BMI. For each study participant, follow-up was from the date of their recruitment to the date of death or Dec 31, 2019, whichever occurred first. Cox models were used to estimate associations between usual clinic or ambulatory blood pressure and mortality, adjusted for confounders and additionally for alternative measures of blood pressure. For each measure of blood pressure, we created five groups (ie, fifths) defined by quintiles of that measure among those who subsequently died.