Table 1
Baseline characteristics of the participants.
| Characteristics | Overall(n = 7605) | Normal QTc interval(n = 6468) | Prolonged QTc interval(n = 1137) | P value |
|---|---|---|---|---|
| Men, n (%) | 2861 (37.6) | 2460 (38.0) | 401 (35.3) | 0.08 |
| Age, years | 58.1 (9.3) | 57.6 (9.2) | 61.1 (9.8) | 0.001 |
| Body mass index, kg/m2 | 25.2 (3.2) | 25.1 (3.2) | 25.7 (3.5) | 0.002 |
| High school education or above, n (%) | 1552 (20.4) | 1354 (20.9) | 198 (17.4) | 0.007 |
| Current smoking, n (%) | 1565 (21.2) | 1368 (21.8) | 197 (17.9) | 0.004 |
| Physical activity, mild/moderate/vigorous (%) | 65.5/21.3/13.2 | 64.4/21.5/14.1 | 71.4/20.3/8.3 | <0.0001 |
| Systolic blood pressure, mmHg | 141.1 (19.9) | 139.8 (19.4) | 148.7 (21.1) | 0.0001 |
| Diastolic blood pressure, mmHg | 82.9 (10.4) | 82.5 (10.1) | 85.2(11.2) | <0.0001 |
| Fasting blood glucose, mmol/L | 5.6 (1.5) | 5.5 (1.4) | 5.9 (2.0) | <0.0001 |
| OGTT-2h blood glucose, mmol/L | 8.2 (4.3) | 8.0 (4.1) | 9.5 (5.2) | <0.0001 |
| Serum triglyceride, mmol/L | 1.4 (1.0, 1.9) | 1.3 (1.0, 1.9) | 1.6 (1.1, 2.2) | 0.11 |
| Serum total cholesterol, mmol/L | 5.4 (1.0) | 5.3 (1.0) | 5.5 (1.0) | 0.50 |
| Serum HDL cholesterol, mmol/L | 1.3 (0.3) | 1.3 (0.3) | 1.3 (0.3) | 0.27 |
| Serum LDL cholesterol, mmol/L | 3.2 (0.9) | 3.2 (0.9) | 3.2 (0.9) | 0.81 |
| Diabetes, n (%) | 1359 (17.9) | 1047 (16.2) | 312 (27.4) | <0.0001 |
| Hypertension, n (%) | 4565 (60.1) | 3716 (57.5) | 849 (74.7) | <0.0001 |
| Heart rate, bpm | 76.3 (0.9) | 76.2 (11.8) | 76.7 (12.3) | 0.36 |
| QT interval, ms | 387.2 (31.7) | 383.1 (27.2) | 410.4 (43.4) | <0.0001 |
| QTc interval, ms | 432.7 (30.2) | 424.6 (19.8) | 479.3 (36.2) | <0.0001 |
[i] Data are presented as mean (SD), median (inter-quartile ranges), or proportions. Linear regression for continuous variables and Cochran Armitage trend chi-square test for categorical variables were applied to analyze the difference according to whether prolonged QTc interval happen. OGTT: oral glucose tolerance test; HDL cholesterol: high density lipoprotein cholesterol; LDL cholesterol: low density lipoprotein cholesterol; QTc interval: corrected QT for heart rate using Bazett’s formula [QTc-Baz = QT (heart rate/60)1/2]; prolonged QTc interval: QTc interval ≥450 ms in men or QTc interval ≥460 ms in women.
Table 2
Association between QTc interval and cardiovascular diseases, stroke, and myocardial infraction in Chinese population.
| Events(n, %) | Incidence rates(per 1000 PYs) | QTc interval(per 1-SD increase)* | QTc interval(prolonged† vs. normal) | |||
|---|---|---|---|---|---|---|
| HR (95% CI) | P value | HR (95% CI) | P value | |||
| Cardiovascular diseases | 419 (5.5) | 12.0 | ||||
| Model 1 | 1.17 (1.09, 1.26) | <0.0001 | 1.99 (1.60, 2.48) | <0.0001 | ||
| Model 2 | 1.09 (1.01,1.19) | 0.04 | 1.62 (1.30, 2.03) | <0.0001 | ||
| Model 3 | 1.07 (0.98, 1.17) | 0.13 | 1.51 (1.20, 1.90) | 0.0004 | ||
| Stroke | 385 (5.1) | 11.0 | ||||
| Model 1 | 1.16 (1.07, 1.25) | 0.0002 | 1.92 (1.52, 2.42) | <0.0001 | ||
| Model 2 | 1.08 (0.99, 1.18) | 0.09 | 1.57 (1.25, 1.99) | 0.0001 | ||
| Model 3 | 1.06 (0.97, 1.16) | 0.23 | 1.48 (1.16, 1.88) | 0.002 | ||
| Myocardial infraction | 36 (0.5) | 1.0 | ||||
| Model 1 | 1.24 (1.00, 1.53) | 0.048 | 2.50 (1.23, 5.07) | 0.01 | ||
| Model 2 | 1.20 (0.93, 1.53) | 0.16 | 1.84 (0.89, 3.80) | 0.10 | ||
| Model 3 | 1.13 (0.86, 1.48) | 0.37 | 1.52 (0.73, 3.17) | 0.26 | ||
[i] Data are presented as hazard ratio (HR) and 95% confidence interval (CI). *Corrected QT for heart rate using Bazett’s formula (QTc-Baz = QT [heart rate/60]1/2), 1-SD: standard deviation, 30.2 ms; †Prolonged QTc interval: QTc interval ≥ 450 ms in men or QTc interval ≥ 460 ms in women; PY: person years. Model 1, unadjusted; Model 2, adjusted for sex, age; Model 3, further adjusted for BMI, education, current smoking, physical activity, diabetes, hypertension, serum total cholesterol, triglycerides, HDL cholesterol and LDL cholesterol based on model 2. BMI: body mass index; HDL cholesterol: high density lipoprotein cholesterol; LDL cholesterol: low density lipoprotein cholesterol.
Table 3
Association of QTc interval with vascular markers using repeated measurements.
| Baseline | Follow-up | QTc interval(per 1-ms increase) | QTc interval(prolonged* vs. normal) | |||
|---|---|---|---|---|---|---|
| β (SE) | P value | β (SE) | P value | |||
| baPWV, cm/s | 1585 (345) | 1661 (344) | 0.56 (0.11) | <0.0001 | 38.10 (8.04) | <0.0001 |
| CIMT, mm | 0.6 (0.1) | 0.7 (0.2) | 0.0001 (0.0001) | 0.03 | 0.01 (0.01) | 0.04 |
[i] Parameter estimates were computed from separate generalized estimating equation analysis model with each variable at a time after adjustment for sex, age, BMI, current smoking, physical activity, education, diabetes, hypertension, serum total cholesterol, triglycerides, HDL cholesterol and LDL cholesterol. *Prolonged QTc interval: QTc interval ≥ 450 ms in men or QTc interval ≥ 460 ms in women; baPWV: brachial-ankle pulse wave velocity; CIMT: carotid intima-media thickness; SE: standard error.
Figure 1
Incidences of microalbuminuria (A) and PAD (B) according to subgroups, comparing the prolonged QTc interval group with the normal QTc interval group. Prolonged QTc interval: QTc interval ≥ 450 ms in men or QTc interval ≥ 460 ms in women; PAD: peripheral arterial disease.