Table 1.
Baseline characteristics of unassisted cardiopulmonary resuscitation and dispatcher-assisted cardiopulmonary resuscitation groups before/after propensity score matching
| Characteristic | Prepropensity score matching | Postpropensity score matching | ||||
|---|---|---|---|---|---|---|
| Unassisted CPR | DA-CPR | ASDa | Unassisted CPR | DA-CPR | ASDa | |
| (n = 16 979) | (n = 42 709) | (n = 16 979) | (n = 16 979) | |||
| Year | ||||||
| 2013 | 3490 (20.6) | 7799 (18.3) | 0.06 | 3490 (20.6) | 3492 (20.6) | <0.01 |
| 2014 | 3587 (21.1) | 8220 (19.2) | 0.05 | 3587 (21.1) | 3608 (21.3) | <0.01 |
| 2015 | 3322 (19.6) | 8439 (19.8) | <0.01 | 3322 (19.6) | 3371 (19.9) | 0.01 |
| 2016 | 3295 (19.4) | 8909 (20.9) | 0.04 | 3295 (19.4) | 3277 (19.3) | <0.01 |
| 2017 | 3285 (19.4) | 9342 (21.9) | 0.06 | 3285 (19.4) | 3231 (19.0) | 0.01 |
| Sex – man | 9264 (54.6) | 24 996 (58.5) | 0.08 | 9264 (54.6) | 9303 (54.8) | <0.01 |
| Age (years), mean (SD) | 77.4 (14.9) | 76.7 (14.8) | 0.04 | 77.4 (14.9) | 77.5 (14.9) | 0.04 |
| Initial cardiac rhythm | ||||||
| Shockable | 3133 (18.5) | 9254 (21.7) | 0.08 | 3133 (18.5) | 3462 (20.4) | 0.08 |
| Geographic Japanese regions | ||||||
| Rural areab | 4216 (24.8) | 10 428 (24.4) | 0.01 | 4216 (24.8) | 4224 (24.9) | <0.01 |
| Bystander witness status | ||||||
| Witnessed by family member | 5500 (32.4) | 27 030 (63.3) | 0.65 | 5500 (32.4) | 5500 (32.4) | <0.01 |
| Witnessed by nonfamily member | 11 479 (67.6) | 15 679 (36.7) | 0.65 | 11 479 (67.6) | 11 479 (67.6) | <0.01 |
| Collapse-to-call time (minutes), mean (SD) | 2.1 (7.7) | 3.4 (6.8) | 0.18 | 2.3 (7.6) | 2.5 (6.6) | 0.03 |
| Call-to-EMS response time (minutes), mean (SD) | 9.5 (4.1) | 9.5 (3.9) | 0.01 | 9.4 (4.1) | 9.5 (4.2) | 0.04 |
| Collapse-to-first-CPR time (minutes), mean (SD) | 2.2 (4.6) | 4.2 (6.0) | 0.37 | 2.3 (4.6) | 3.2 (5.3) | 0.19 |
| Collapse-to-first-rhythm-analysis time (minutes), mean (SD) | 11.7 (7.9) | 13.1 (7.3) | 0.17 | 11.9 (7.9) | 12.2 (7.0) | 0.04 |
| Bystander CPR durationc (minutes), mean (SD) | 9.6 (7.7) | 9.0 (6.1) | 0.09 | 9.7 (7.7) | 9.1 (6.5) | 0.08 |
Values are reported as n (%) unless indicated otherwise.
ASD, absolute standardised difference; CPR, cardiopulmonary resuscitation; DA, dispatcher-assisted; EMS, emergency medical services.
a
An ASD of equal or more than 0.1 was considered to indicate a substantial imbalance between the two groups.
b
The rural area is constituted 19 prefectures with population of less than 200 inhabitants per km2.
c
Values were missing for 52 patients (0.09 %) before propensity score matching and for 44 patients (0.13%) after propensity score matching.