Seasonal variations in office and home blood pressures in hypertensive patients treated with antihypertensive drugs

OBJECTIVE: To analyze various factors influencing season variations in blood pressure under ordinary circumstances. METHODS: We examined home and office blood pressures in 315 outpatients with essential hypertension. The majority (88%) were being administered antihypertensived drugs. Their office and home blood pressures were recorded in 1993. The patients were 156 men and 159 women, aged 60.8 +/- 0.6 years (mean +/- SEM). The office blood pressure was measured monthly by the same physicians. The home blood pressure was measured every day by the patients, in the morning and evening. RESULTS: The home blood pressures both in men and in women exhibited significant seasonal variations, to a similar extent. The winter-summer difference in home blood pressure was 3.9 +/- 0.5 mmHg systolic and 1.7 +/- 0.3 mmHg diastolic for the men and 4.6 +/-0.5 mmHg systolic and 2.4 +/- 0.3 mmHg diastolic for the women. The office blood pressure of the men also exhibited significant seasonal variation. There was no seasonal variation in office systolic blood pressure in the women. The levels of home blood pressure in the men and women were similar during each season, whereas the office systolic blood pressure of the women was significantly higher than that of men throughout the year. For the total group of patients, the winter-summer differences in home systolic blood pressure was positively correlated to age. The seasonal variations in blood pressure were not affected by body mass index, smoking status, and administration of antihypertensive medication.CONCLUSIONS: Seasonal variations in blood pressure existed both for male and for female hypertensive patients and occurred even for subjects being treated with antihypertensive drugs. However, there was no seasonal variation in the office systolic blood pressure of women, suggesting that the differences between the office and home blood pressures and between thermoregulatory mechanisms for the sexes may have obscured it.