Differences in background, characteristics and time factors for out-of-hospital cardiac arrest before and after propensity score matching for neurologically favourable 1-month survival
| Background, characteristics and time factors | Before propensity score matching | Unadjusted OR (95% CI) with all other times of day as reference or P value | After propensity score matching | Unadjusted OR (95% CI) with all other times of day as reference or P value | ||
| School hours on school days (n=412) | All other times of day (n=1248) | School hours on school days (n=366) | All other times of day (n=366) | |||
| Male patients, % (n) | 63.6 (262) | 70.9 (885) | 0.72 (0.57 to 0.91) | 65.0 (238) | 63.4 (232) | 1.07 (0.79 to 1.45) |
| Classification of students, % (n) | ||||||
| Lower grades in elementary school | 8.0 (33) | 13.9 (173) | <0.01 | 9.0 (33) | 9.3 (34) | 0.95 |
| Higher grades in elementary school | 25.2 (104) | 18.0 (225) | 24.0 (88) | 24.9 (91) | ||
| Junior high school | 23.8 (98) | 21.0 (262) | 22.4 (82) | 23.5 (86) | ||
| High school | 43.0 (177) | 47.1 (588) | 44.5 (163) | 42.4 (155) | ||
| Family bystander-witnessed OHCA, % (n) | 22.1 (91) | 43.0 (536) | 0.38 (0.29 to 0.49) | 24.9 (91) | 25.7 (94) | 0.96 (0.69 to 1.34) |
| Presumed cardiac aetiology, % (n) | 42.0 (173) | 28.6 (357) | 1.81 (1.43 to 2.28) | 37.2 (136) | 35.8 (131) | 1.06 (0.79 to 1.43) |
| Exogenous causes, % (n) | 39.1 (161) | 52.6 (656) | 0.58 (0.46 to 0.73) | 43.4 (159) | 44.0 (161) | 0.98 (0.73 to 1.31) |
| Shockable initial rhythm, % (n) | 23.5 (97) | 15.8 (197) | 1.64 (1.25 to 2.16) | 21.6 (79) | 21.6 (79) | 1.00 (0.70 to 1.42) |
| BCPR, % (n) | ||||||
| No BCPR | 42.7 (176) | 56.4 (704) | <0.01 | 46.2 (169) | 45.1 (165) | 0.85 |
| CC-only BCPR | 27.7 (114) | 25.4 (317) | 29.0 (106) | 30.9 (113) | ||
| Conventional* BCPR | 29.6 (122) | 18.2 (227) | 24.9 (91) | 24.0 (88) | ||
| DA-CPR provision, % (n) | 34.5 (142) | 34.3 (428) | 1.01 (0.80 to 1.27) | 34.4 (126) | 33.6 (123) | 1.04 (0.76 to 1.41) |
| Call-first action by a bystander, % (n) | 59.7 (141/236) | 71.1 (387/544) | 0.61 (0.44 to 0.84) | 58.4 (115/197) | 65.7 (132/201) | 0.76 (0.50 to 1.15) |
| Public access defibrillation, % (n) | 12.9 (53) | 3.3 (41) | 4.35 (2.84 to 6.64) | 7.4 (27) | 10.1 (37) | 0.71 (0.42 to 1.19) |
| Tracheal intubation by paramedics, % (n) | 2.7 (11) | 3.3 (41) | 0.81 (0.41 to 1.59) | 2.7 (10) | 3.3 (12) | 0.83 (0.35 to 1.94) |
| Epinephrine administration by paramedics, % (n) | 7.3 (30) | 4.4 (54) | 1.72 (1.09 to 2.74) | 6.3 (23) | 5.7 (21) | 1.10 (0.60 to 2.03) |
| Time intervals (min), median (IQR) | ||||||
| Witness-to-first CPR interval | 4 (1–10) | 8 (2–13) | <0.01 | 5 (1–11) | 6 (1–11) | 0.20 |
| EMS response time | 7 (6–9) | 8 (6–10) | <0.01 | 7 (6–9) | 7 (6–10) | 0.10 |
*CPR with chest compressions and mouth-to-mouth ventilations.
BCPR, bystander CPR; CC, chest compression;CPR, cardiopulmonary resuscitation; DA-CPR, dispatcher-assisted CPR; EMS, emergency medical service; OHCA, out-of-hospital cardiac arrest.