Dispatcher instructions for bystander cardiopulmonary resuscitation and neurologically intact survival after bystander-witnessed out-of-hospital cardiac arrests: a nationwide, population-based observational study

Table 1 Baseline characteristics of unmatched and matched patients

Characteristic	Pre-propensity score matching			Post-propensity score matching
	Conventional DA-CPR	Compression-only DA-CPR	ASD^a	Conventional DA-CPR	Compression-only DA-CPR	ASD^a
	(n = 2169)	(n = 22,778)	ASD^a	(n = 2169)	(n = 2169)	ASD^a
Year
2016	1070 (49.3)	11,065 (48.6)	0.02	1070 (49.3)	1084 (50.0)	0.01
2017	1099 (50.7)	11,713 (51.4)	0.02	1099 (50.7)	1085 (50.0)	0.01
Sex, male	1151 (53.1)	13,416 (58.9)	0.12	1151 (53.1)	1154 (53.2)	0.00
Age, y, mean (SD)	76.7 (15.7)	76.5 (14.8)	0.01	76.7 (15.7)	77.2 (14.9)	0.04
Rural regions^b	507 (23.4)	5649 (24.8)	0.03	507 (23.4)	424 (19.6)	0.09
Witnessed by family member	944 (43.5)	15,028 (66.0)	0.46	944 (43.5)	951 (43.9)	0.01
Presumed cardiac cause	1292 (59.6)	13,783 (60.5)	0.02	1292 (59.6)	1309 (60.4)	0.02
Call-to-response time, min, mean (SD)	10.1 (4.3)	9.5 (3.9)	0.14	10.1 (4.3)	10.1 (4.2)	0.01
Initial shockable rhythm	304 (14.0)	3463 (15.2)	0.03	304 (14.0)	297 (13.7)	0.01
Advanced airway management	1052 (48.5)	10,530 (46.2)	0.05	1052 (48.5)	979 (45.1)	0.07
Epinephrine administration	702 (32.4)	7565 (33.2)	0.02	702 (32.4)	711 (32.8)	0.01
Collapse-to-initiation of DA-CPR time, min, mean (SD)	3.7 (5.2)	4.7 (5.9)	0.17	3.7 (5.2)	4.2 (5.6)	0.09
Duration of DA-CPR, min, mean (SD)	8.1 (4.0)	7.5 (3.7)	0.17	8.1 (4.0)	7.9 (4.0)	0.05

Values are reported as n (%) unless indicated otherwise
ASD absolute standardsed difference; DA-CPR dispatcher-assisted cardiopulmonary resuscitation; PS propensity score; SD standard deviation
^aAn ASD of equal or more than 0.1 was considered to indicate a substantial imbalance between the two groups
^bThe rural area constituted 19 prefectures with a population of less than 200 inhabitants per km²

ISSN: 1364-8535