Seasonal Variation of Home Blood Pressure and Its Association With Target Organ Damage: The J-HOP Study (Japan Morning Surge-Home Blood Pressure)

BACKGROUND: Although seasonal variation of home blood pressure (BP) has been reported to be higher in winter, seasonal difference in home BP (HBP) and its association with target organ damage (TOD) remains unclear. METHODS: This is a cross-sectional study using the dataset from the Japan Morning Surge-Home Blood Pressure (J-HOP) study to assess seasonal differences in HBP, prevalence of masked hypertension, and association of HBP with TOD. The J-HOP study is a nationwide, multicenter prospective study whose participants with cardiovascular risks underwent morning and evening HBP measurements for a 14-day period in 71 institutions throughout Japan. Urine albumin–creatinine ratio (UACR) and serum-B-type natriuretic peptide (BNP) were obtained at enrollment. RESULTS: Among 4,267 participants (mean age, 64.9 ± 10.9 years; 46.9% male; 91.4% hypertensives), 1,060, 979, 1,224, and 1,004 participants were enrolled in spring, summer, autumn, and winter, respectively. Morning and evening home systolic/diastolic BP levels, and prevalence of masked hypertension (office BP <140/90 mm Hg and HBP ≥135/85 mm Hg) were significantly lower in summer than other seasons after adjustment for covariates. When we assessed the interaction between BP parameters and each season for an association with TOD, we found the association between morning home diastolic BP and each of UACR and BNP was stronger in winter than other seasons (both P for interaction <0.05). CONCLUSIONS: In this study, we revealed that the prevalence of masked hypertension was higher in other seasons than in summer and found a notable association between morning home diastolic BP and TOD in winter.