Table 1. Baseline Characteristics of Participants by Fourths of the Distribution of Overall Systolic Variability Independent of the Mean in the Morning.
| Characteristic | Categories of Systolic Blood Pressure Variability | P Value | |||
|---|---|---|---|---|---|
| Limits, units | |||||
| Women | 0.79–6.78 | 6.78–8.61 | 8.61–10.5 | 10.5–22.3 | |
| Men | 0.86–6.32 | 6.32–7.81 | 7.83–9.67 | 9.67–24.6 | |
| Number of participants, % | |||||
| All participants in category | 604 | 606 | 606 | 605 | |
| Antihypertensive treatment | 118 (19.5) | 142 (23.4) | 181 (29.9)* | 215 (35.5)* | <0.0001 |
| Smokers | 123 (20.4) | 122 (20.1) | 124 (20.5) | 106 (17.5) | 0.52 |
| Drinking alcohol | 111 (26.1) | 129 (27.9) | 125 (26.2) | 106 (23.6) | 0.52 |
| Diabetes mellitus | 45 (7.5) | 66 (10.9)* | 53 (8.8) | 55 (9.1) | 0.22 |
| Cardiovascular disease | 11 (1.8) | 18 (3.0) | 15 (2.5) | 26 (4.3) | 0.068 |
| Mean (SD) of characteristic | |||||
| Age, y | 55.2 (12.0) | 56.6 (11.3) | 59.6 (12.2)† | 62.8 (12.5)† | <0.0001 |
| Body mass index, kg/m2 | 23.9 (2.9) | 23.6 (2.8) | 23.2 (2.9) | 23.1 (2.9) | <0.0001 |
| Serum total cholesterol, mmol/L | 5.00 (0.79) | 5.03 (0.91) | 5.02 (0.80) | 4.94 (0.85) | 0.42 |
| Systolic blood pressure, mm Hg | 123.7 (15.0) | 123.2 (14.2) | 124.0 (15.4) | 124.5 (15.1) | 0.61 |
| Diastolic blood pressure, mm Hg | 75.9 (10.1) | 75.0 (9.4) | 74.2 (9.7) | 73.4 (10.1) | <0.0001 |
| Heart rate, beats per minute | 68.0 (7.6) | 68.0 (7.3) | 67.2 (7.9) | 66.8 (8.0) | 0.0012 |
| Mean (SD) of variability index | |||||
| SD, mm Hg | 5.3 (1.3) | 7.4 (1.2)† | 9.2 (1.5)† | 12.4 (2.9)† | <0.0001 |
| Coefficient of variation, % | 4.3 (0.9) | 6.0 (0.5)† | 7.4 (0.6)† | 9.9 (1.8)† | <0.0001 |
| Maximum-minimum difference, mm Hg | 20.7 (6.1) | 29.2 (6.3)† | 35.9 (7.8)† | 46.8 (12.6)† | <0.0001 |
| Average real variability, mm Hg | 5.6 (1.6) | 7.7 (1.7)† | 9.5 (2.1)† | 12.6 (3.5)† | <0.0001 |
Values are number of participants (%) or arithmetic mean (SD). Blood pressure variability is based on self-measurement in the morning on 5 days within 1 hour after awakening and before taking antihypertensive medications in treated participants. Drinking status was unavailable in 608 participants. P denotes the significance of the linear trend across categories of systolic blood pressure level.
*
P<0.05, significance of the difference with the adjacent lower fourth.
†
P<0.0001, significance of the difference with the adjacent lower fourth.