Seasonal variations of daily changes in blood pressure among hypertensive patients with end-stage renal diseases.

Hypertension is a well-known cardiovascular risk. Patients with end-stage renal diseases frequently suffer hypertension, and their blood pressure elevates in winter. However, seasonal changes in daily variations of blood pressure are poorly assessed in patients treated with hemodialysis. Thirty hypertensive patients with end-stage renal diseases were enrolled in the study. Dry weight and antihypertensive medications were altered when they were necessary. Home blood pressure measurements were performed at least for 1 week in each season; April-May 2008, July-August 2008, October-November 2008, and January-February 2009. Both morning and evening systolic blood pressures (SBPs) showed significant seasonal changes ( p < 0.01), with the highest blood pressure in winter (162 +/- 18 and 135 +/- 22 mmHg in morning and evening). Morning diastolic blood pressure (DBP) also exhibited seasonal changes ( p < 0.05), with the highest blood pressure in fall ( 78 +/- 8 mmHg). Evening DBP did not manifest seasonal deviations. Morning-evening differences in SBP and DBP were the greatest in winter (28 +/- 21 and 10 +/- 9 mmHg in SBP and DBP, p < 0.01), and the smallest in summer (16 +/- 12 and 6 +/- 5 mmHg). Daily variations of SBP and DBPs in spring (19 +/- 12 and 7 +/- 6 mmHg) and fall (20 +/- 13 and 9 +/- 8 mmHg) were between those of summer and winter. Our results indicate that not only averaged blood pressure but also variations of blood pressure in winter are larger than the other seasons, and suggest that these blood pressure variations participate in cardiovascular events in hypertensive patients with end-stage renal diseases.