Association Between Amplitude of Seasonal Variation in Self‐Measured Home Blood Pressure and Cardiovascular Outcomes: HOMED‐BP (Hypertension Objective Treatment Based on Measurement By Electrical Devices of Blood Pressure) Study

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.