Background: The aim of this study is to clarify associations between orthostatic blood pressure (BP) change, as well as possible physiological factors, and day-to-day home BP variability, a promising risk factor for cardiovascular outcomes.
Methods: Study participants were 6,465 community residents (age 58.3 years). Home BP was measured every morning and evening for 7 days. Orthostatic BP was calculated as the maximum difference between BP measured while sitting and remeasured after 1 and 3 minutes standing.
Results: Frequency of individuals who showed orthostatic BP decline was as follows: systolic BP (SBP) change ≥-20 mm Hg: 2.6%, ≥-10 mm Hg: 14.1%. These subgroups showed larger home SBP variability (average real variability: 11.3 ± 5.3, 8.7 ± 3.9 mm Hg) when compared with orthostatic normotensives (7.6 ± 3.7 mm Hg) (all P < 0.001). Multiple linear regression analysis adjusted for major covariates, including seated BP, identified orthostatic BP drop as an independent determinant for morning BP variability (≥-20 mm Hg: β = 0.037, P = 0.003; ≥-10 mm Hg: β = 0.026, P = 0.036) but not for evening BP variability. Carotid hypertrophy was significantly associated with home BP variability (morning: β = 0.052, P = 0.001; evening: β = 0.065, P < 0.001) and showed a U-shaped association with orthostatic BP change. Plasma B-type natriuretic peptide level, a previously suggested factor for BP variability, did not show significant association with morning and evening BP variability.
Conclusion: Orthostatic BP decline was significantly associated with morning BP variability. Large artery atherosclerosis was a common risk factor.