Seasonal variation in the office and ambulatory blood pressure control in patients treated with two dual antihypertensive therapies.

We investigated seasonal variation in the office and ambulatory blood pressure control in hypertensive patients treated with two single-pill dual-combination antihypertensive therapies. The study participants (n = 560) were hypertensive patients enrolled in a 24-week therapeutic study. Antihypertensive treatment was initiated with amlodipine/benazepril 5/10 mg/day or benazepril/hydrochlorothiazide 10/12.5 mg/day, with the possible up-titration to 10/20 mg/day or 20/25 mg/day during follow-up, respectively. Office blood pressure was measured at each clinic visit, and ambulatory blood pressure monitoring was performed at baseline and 24-week follow-up. At 24 weeks of follow-up, in patients who continued antihypertensive treatment (n = 511), the proportion of up-titration to higher dosages was significantly different across seasons of treatment commencement in the benazepril/hydrochlorothiazide group (P = 0.002), but not in the amlodipine/benazepril group (P = 0.84). The between-group difference was significantly different in 134 patients who commenced treatment in winter (18.9% vs. 5.0%, P = 0.02), but not in 377 patients who commenced treatment in the other seasons (P ≥ 0.33). The control rate of office blood pressure (<140/90 mmHg) was significantly different across seasons of treatment commencement in the amlodipine/benazepril group (P = 0.01), but not in the benazepril/hydrochlorothiazide group (P = 0.16). The mean changes from baseline to 24-week follow-up tended to be smaller in the benazepril/hydrochlorothiazide than amlodipine/benazepril group in 24-h (mean between-group difference, -2.8 mmHg) and daytime diastolic blood pressure (mean between-group difference, -3.2 mmHg) in patients who commenced treatment in winter, though statistical significance was not achieved (P ≥ 0.07). In conclusion, there was seasonality in the clinic and ambulatory blood pressure-lowering effect of antihypertensive drug combinations, with a marginally significant difference in treatment intensity and blood pressure control between treatment with amlodipine or hydrochlorothiazide in combination with benazepril.