Background: The clinical significance of long-term seasonal variations in self-measured home blood pressure (BP) has not been elucidated for the cardiovascular disease prevention.
Methods and results: Eligible 2787 patients were classified into 4 groups according to the magnitude of their seasonal variation in home BP, defined as an average of all increases in home BP from summer (July-August) to winter (January-February) combined with all decreases from winter to summer throughout the follow-up period, namely inverse- (systolic/diastolic, <0/<0 mm Hg), small- (0-4.8/0-2.4 mm Hg), middle- (4.8-9.1/2.4-4.5 mm Hg), or large- (≥9.1/≥4.5 mm Hg) variation groups. The overall cardiovascular risks illustrated U-shaped relationships across the groups, and hazard ratios for all cardiovascular outcomes compared with the small-variation group were 3.07 (P=0.004) and 2.02 (P=0.041) in the inverse-variation group and large-variation group, respectively, based on systolic BP, and results were confirmatory for major adverse cardiovascular events. Furthermore, when the summer-winter home BP difference was evaluated among patients who experienced titration and tapering of antihypertensive drugs depending on the season, the difference was significantly smaller in the early (September-November) than in the late (December-February) titration group (3.9/1.2 mm Hg versus 7.3/3.1 mm Hg, P<0.001) as well as in the early (March-May) than in the late (June-August) tapering group (4.4/2.1 mm Hg versus 7.1/3.4 mm Hg, P<0.001).
Conclusions: The small-to-middle seasonal variation in home BP (0-9.1/0-4.5 mm Hg), which may be partially attributed to earlier adjustment of antihypertensive medication, were associated with better cardiovascular outcomes.
Keywords: cardiovascular outcomes; home blood pressure; hypertension; population studies; seasonal variation.
© 2018 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.