impact of baseline systolic blood pressure on visit-to-visit blood pressure variability: the kailuan study

Anxin Wang,1–5,* Zhifang Li,6,* Yuling Yang,6 Guojuan Chen,6 Chunxue Wang,1–4 Yuntao Wu,7 Chunyu Ruan,7 Yan Liu,7 Yilong Wang,1–4 Shouling Wu7 1Department of Neurology, Beijing Tiantan Hospital, Capital Medical University, 2China National Clinical Research Center for Neurological Diseases, 3Center of Stroke, Beijing Institute for Brain Disorders, 4Beijing Key Laboratory of Translational Medicine for Cerebrovascular Disease, 5Department of Epidemiology and Health Statistics, School of Public Health, Capital Medical University, Beijing, 6Graduate School, 7Department of Cardiology, Kailuan Hospital, North China University of Science and Technology, Tangshan, People’s Republic of China *These authors contributed equally to this work 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.Conclusion: 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. Keywords: blood pressure variability, coefficient of variation, standard deviation, systolic blood pressure