Table 1. Baseline characteristics of patients.
| Time of symptom onset | Midnight–6:00 A.M. | 6:00 A.M.–Noon | Noon–6:00 P.M. | 6:00 P.M.–Midnight | P-value a | ||||
|---|---|---|---|---|---|---|---|---|---|
| Number of cases (%) | 1429 | (21.3) | 2102 | (31.3) | 1572 | (23.4) | 1607 | (24.0) | |
| Age (years): Mean (SD) | 60.7 | (12.9) | 60.7 | (13.1) | 60.3 | (13.3) | 59.7 | (12.9) | 0.99 |
| Male (%) | 1153 | (80.7) | 1651 | (78.5) | 1239 | (78.8) | 1290 | (80.3) | 0.99 |
| Chinese (%) | 887 | (62.1) | 1389 | (66.1) | 1032 | (65.7) | 992 | (61.7) | 0.37 |
| Malay (%) | 302 | (21.1) | 350 | (16.7) | 284 | (18.1) | 335 | (20.9) | |
| Indian (%) | 212 | (14.8) | 329 | (15.7) | 230 | (14.6) | 244 | (15.2) | |
| Other (%) | 28 | (2.0) | 34 | (1.6) | 26 | (1.7) | 36 | (2.2) | |
| Current smoker (%) | 630 | (44.1) | 823 | (39.2) | 691 | (44.0) | 715 | (44.5) | 0.04 |
| Hypertension (%) | 873 | (61.1) | 1200 | (57.1) | 869 | (55.3) | 926 | (57.6) | 0.21 |
| Diabetes mellitus (%) | 627 | (43.9) | 799 | (38.0) | 611 | (38.9) | 690 | (42.9) | 0.03 |
| Dyslipidemia (%) | 1076 | (75.3) | 1600 | (76.1) | 1167 | (74.2) | 1210 | (75.3) | 0.99 |
| Past MI (%) | 204 | (14.3) | 252 | (12.0) | 174 | (11.1) | 211 | (13.1) | 0.83 |
| Weekend admission (%) | 396 | (27.7) | 599 | (28.5) | 469 | (29.8) | 522 | (32.4) | 0.41 |
| Anterior STEMI (%) | 790 | (55.3) | 1064 | (50.6) | 819 | (52.1) | 857 | (53.3) | 0.03 |
| Peak CK concentration (IU/L): mean (SD) | 2590.8 | (2839.1) | 2336.3 | (2386.6) | 2526.8 | (2809.7) | 2522.1 | (2645.2) | 0.03 |
a With Bonferroni correction.
Baseline characteristics of patients categorized according to time of symptom onset. Data expressed as mean ± SD for continuous variables, median (range) for skewed data and percentages for categorical variables. Chi-square test was performed for categorical variables, analysis of variance for parametric continuous variables, Wilcoxon Rank-Sum test for non-parametric continuous variables.