title: Impact of baseline systolic blood pressure on visit-to-visit blood pressure variability: the Kailuan study.
abstract: BACKGROUND
  To investigate the relationship between baseline systolic blood pressure (SBP) and visit-to-visit blood pressure variability in a general population.
  
  
  METHODS
  This is a prospective longitudinal cohort study on cardiovascular risk factors and cardiovascular or cerebrovascular events. Study participants attended a face-to-face interview every 2 years. Blood pressure variability was defined using the standard deviation and coefficient of variation of all SBP values at baseline and follow-up visits. The coefficient of variation is the ratio of the standard deviation to the mean SBP. We used multivariate linear regression models to test the relationships between SBP and standard deviation, and between SBP and coefficient of variation.
  
  
  RESULTS
  Approximately 43,360 participants (mean age: 48.2±11.5 years) were selected. In multivariate analysis, after adjustment for potential confounders, baseline SBPs <120 mmHg were inversely related to standard deviation (P<0.001) and coefficient of variation (P<0.001). In contrast, baseline SBPs ≥140 mmHg were significantly positively associated with standard deviation (P<0.001) and coefficient of variation (P<0.001). Baseline SBPs of 120-140 mmHg were associated with the lowest standard deviation and coefficient of variation. The associations between baseline SBP and standard deviation, and between SBP and coefficient of variation during follow-ups showed a U curve.
  
  
  CONCLUSIONS
  Both lower and higher baseline SBPs were associated with increased blood pressure variability. To control blood pressure variability, a good target SBP range for a general population might be 120-139 mmHg.
authors.affiliation: Department of Neurology, Beijing Tiantan Hospital, Capital Medical University; China National Clinical Research Center for Neurological Diseases; Center of Stroke, Beijing Institute for Brain Disorders; Beijing Key Laboratory of Translational Medicine for Cerebrovascular Disease; Department of Epidemiology and Health Statistics, School of Public Health, Capital Medical University, Beijing.
authors.forename: Anxin
authors.initials: A
authors.lastname: Wang
authors.affiliation: Graduate School.
authors.forename: Zhifang
authors.initials: Z
authors.lastname: Li
authors.affiliation: Graduate School.
authors.forename: Yuling
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Graduate School.
authors.forename: Guojuan
authors.initials: G
authors.lastname: Chen
authors.affiliation: Department of Neurology, Beijing Tiantan Hospital, Capital Medical University; China National Clinical Research Center for Neurological Diseases; Center of Stroke, Beijing Institute for Brain Disorders; Beijing Key Laboratory of Translational Medicine for Cerebrovascular Disease.
authors.forename: Chunxue
authors.initials: C
authors.lastname: Wang
authors.affiliation: Department of Cardiology, Kailuan Hospital, North China University of Science and Technology, Tangshan, People's Republic of China.
authors.forename: Yuntao
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Cardiology, Kailuan Hospital, North China University of Science and Technology, Tangshan, People's Republic of China.
authors.forename: Chunyu
authors.initials: C
authors.lastname: Ruan
authors.affiliation: Department of Cardiology, Kailuan Hospital, North China University of Science and Technology, Tangshan, People's Republic of China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Neurology, Beijing Tiantan Hospital, Capital Medical University; China National Clinical Research Center for Neurological Diseases; Center of Stroke, Beijing Institute for Brain Disorders; Beijing Key Laboratory of Translational Medicine for Cerebrovascular Disease.
authors.forename: Yilong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Cardiology, Kailuan Hospital, North China University of Science and Technology, Tangshan, People's Republic of China.
authors.forename: Shouling
authors.initials: S
authors.lastname: Wu
keywords: blood pressure variability; coefficient of variation; standard deviation; systolic blood pressure