Table 1. Baseline characteristics of study participants.
| Characteristic | Men (n = 2,995) | Women (n = 2,995) |
| Age (years) | 54.8 (11.6) | 55.8 (12.4) |
| Race | ||
| Non-Hispanic white | 81.2 | 78.4 |
| Non-Hispanic black | 8.3 | 10.1 |
| Mexican-American | 3.8 | 3.5 |
| Systolic blood pressure (mmHg) | 128.8 (16.4) | 127.2 (19.2) |
| Total cholestrol (mg/dL) | 212.3 (39.0) | 220.8 (43.5) |
| HDL (mg/dL) | 45.0 (14.0) | 56.1 (16.0) |
| BMI (kg/m2) | 27.3 (4.5) | 27.1 (6.2) |
| Estimated-GFR (mL/min/1.73 m2) | 86.1 (18.9) | 84.6 (25.7) |
| Diabetes | 9.1 | 7.5 |
| Myocardial infarction | 6.1 | 2.6 |
| Congestive heart failure | 2.6 | 1.8 |
| Smoking | ||
| Current | 27.9 | 20.8 |
| Former | 44.8 | 24.8 |
| Never | 27.3 | 54.4 |
| Consume alcohol | 59.1 | 38.3 |
| Use QT prolonging medication | 9.6 | 12.3 |
| Thyroxin (T4, nmol/L) | 107.0 (24.7) | 112.9 (26.8) |
| Thyrotropin (TSH, mU/L) | 1.7 (0.9) | 1.9 (0.9) |
| ECG parameters | ||
| Heart rate (beat/min) | 66.7 (11.3) | 69.2 (11.0) |
| PRrra (ms) * | 165.1 (26.4) | 159.3 (25.3) |
| QRS (ms) | 99.6 (9.3) | 93.5 (9.2) |
| QTrra (ms) * | 403.1 (18.4) | 407.5 (18.7) |
| JTrra (ms) * | 303.5 (18.1) | 314.0 (18.3) |
Values are means (SD) or percentages unless otherwise noted.
*
. PRrra, QTrra, JTrra: RR-interval, race-, and age corrected PR, QT, and JT intervals.