TABLE 1—
Characteristics of the Study Population of Out-of-Hospital Cardiac Arrest Cases: Helsinki, Finland, 1997–2018
| Characteristic | Autumn, No. (%) | Winter, No. (%) | Spring, No. (%) | Summer, No. (%) | All Seasons, No. (%) |
| All | 1359 (100.0) | 1575 (100.0) | 1478 (100.0) | 1265 (100.0) | 5677 (100.0) |
| Sex | |||||
| Male | 893 (65.7) | 1018 (64.6) | 983 (66.5) | 811 (64.1) | 3705 (65.3) |
| Female | 466 (34.3) | 557 (35.4) | 495 (33.5) | 454 (35.9) | 1972 (34.7) |
| Age, y | |||||
| 18–64 | 535 (39.4) | 558 (35.4) | 612 (41.4) | 532 (42.1) | 2237 (39.4) |
| ≥ 65 | 824 (60.6) | 1017 (64.6) | 866 (58.6) | 733 (57.9) | 3440 (60.6) |
| Presumed etiology | |||||
| Cardiac | 935 (68.8) | 1074 (68.2) | 992 (67.1) | 838 (66.2) | 3839 (67.6) |
| Noncardiac | 424 (31.2) | 501 (31.8) | 486 (32.9) | 427 (33.8) | 1838 (32.4) |
| Primary rhythm | |||||
| VF or VT | 499 (36.7) | 495 (31.4) | 481 (32.5) | 377 (29.8) | 1852 (32.6) |
| ASY or PEA | 852 (62.7) | 1075 (68.3) | 991 (67.1) | 883 (69.8) | 3801 (67.0) |
| Not recorded | 8 (0.6) | 5 (0.3) | 6 (0.4) | 5 (0.4) | 24 (0.4) |
| Decade | |||||
| 1997–2007 | 690 (50.8) | 827 (52.5) | 740 (50.1) | 655 (51.8) | 2912 (51.3) |
| 2008–2018 | 669 (49.2) | 748 (47.5) | 738 (49.9) | 610 (48.2) | 2765 (48.7) |
Note. ASY = asystole; OHCA = out-of-hospital cardiac arrest; PEA = pulseless electrical activity; VF = ventricular fibrillation; VT = ventricular tachycardia.