Table 1.

Main characteristics of the included studies.

Author (year)	Country	Study design	Definition of hemodynamically unstable	Sample	Intervention	Death/survival	Age, mean ± SD, y	Sex (male%)	NOS
						(OR for mortality)
Lin (2010) [17]	China	Retrospective	Hypovolemic shock (shock index 1.7–3.0)	92	AE	3/36	35.3 ± 9.5	67	9
					Non-AE	21/32	37.2 ± 5.7	81
Lin (2017) [18]	China	Retrospective	Hypovolemic shock (shock index 1.7–3.0)	65	AE	3/29	38.1 ± 4.5	78	9
					Non-AE	13/20	39.2 ± 5.7	79
Zheng (2006) [19]	China	Retrospective	Hypovolemic shock (shock index 1.5–3.0)	68	AE	2/46	34.0 ± 8.5	78	9
					Non-AE	8/12	37.5 ± 9.5
Esmer (2017) [20]	Germany	Retrospective	Systolic BP <100 mmHg and shock index >1	104	EF	9/38	40.2 ± 15	69	9
					Non-EF	19/38	49.2 ± 23.2
Doussoux (2006) [21]	Spain	Retrospective	Systolic BP <90 mmHg or transfusion needs higher than 2 units of red cells in first 12 h	79	EF	7/40	38.8 ± 15.6	70	9
					Non-EF	8/24
Furugori (2022) [22]	Japan	Retrospective	Systolic BP <90 mmHg	2806	AE	0.7 (0.53–0.92)	NA	NA	9
Hsu (2016) [23]	Australia	Prospective	Systolic BP <90 mmHg and/or initial base deficit >5	24	AE	3/7	60.3 ± 23.5	83	9
					EPP	1/13	49.9 ± 17.5
Jang (2022) [24]	Korea	Retrospective	Systolic BP <90 mmHg or serum lactate level of ≥2 mmol/L	157	EPP	0.711 (0.198–2.551)	59.3 ± 17.3	68	8
					REBOA	12.183 (2.039–72.801)
Costantini (2016) [25]	United States	Prospective	Systolic BP <90 mmHg or heart rate >120 beats per minute or base deficit >6	23	AE	5/12	NA	NA	7
					EPP	3/3
Osborn (2009) [26]	United States	Prospective	Persistent systolic BP <90 mmHg (after receiving 2000 ml of intravenous crystalloid)	40	EPP	4/16	37.9 ± 18.9	NA	8
					Non-EPP	6/14	39.5 ± 17.4
Fangio (2005) [27]	France	Retrospective	Systolic BP <90 mmHg after an additional infusion of normal saline (500 mL) and a continuous infusion of dopamine	32	AE	9/16	39 ± 17	63	7
					Non-AE	1/6	30 ± 5
Shim (2018) [3]	Korea	Retrospective	Persistent systolic BP <90 mmHg despite the loading of two units of packed red cells	58	EPP	12/18	62.5 ± 14.4	67	9
					Non-EPP	16/12	57.0 ± 22.8	57
Matsumoto (2020) [6]	Japan	Retrospective	Systolic BP <90 mmHg or heart rate >120 beats/min at admission	3149	EF	0.75 (058–0.98)	53.5 ± 21.4	58	9
					REBOA	4 (2.87–5.58)
Ha et al. (2017) [28]	Korea	Retrospective	Hemorrhagic shock	53	EPP	5/23	NA	NA	7
					Non-EPP	12/13
Chiara (2016) [29]	Italy	Retrospective	Persistent systolic BP <90 mmHg despite pelvic binder and ≥2 L of intravenous crystalloids and transfusion of ≥2 units of RBCs	78	EPP	10/20	55.3 ± 21.8	57	9
					Non-EPP	21/27	48.5 ± 20.8	73
Frassini (2021) [30]	Italy	Retrospective	Systolic BP <90 mmHg despite pelvic binder and 1 L of intravenous crystalloids and transfusion of ≥2 units of red cells	74	EPP	8/16	NA	60	9
					Non-EPP	29/21		73
Miller (2003) [31]	United States	Retrospective	Hypotension	35	EF	6/10	46 ± 51	80	7
					Non-EF	13/6
Cheng (2015) [32]	Hong Kong, China	Retrospective	Systolic BP <90 mmHg upon arrival at AED or at any time during hospital stay after infusion of 2 L of crystalloids	199	EPP	0.223 (0.052–0.947)	NA	56	9
Jang (2019) [33]	Korea	Retrospective	Persistent systolic BP <90 mmHg despite 2 L crystalloid loading and transfusion of 2 units of red cells	50	EF	1/6	59.6 ± 18.6	56	9
					Non-EF	15/28
Werner (2022) [34]	United States	Retrospective	Persistent systolic BP <90 mmHg after initial transfusion of 2 units of red cells in the emergency department	78	REBOA	5/26	50 ± 17.6	74	9
					Non-REBOA	6/41	49 ± 17.6	68
Lee (2022) [35]	Korea	Retrospective	Systolic BP <90 mmHg during the initial resuscitation despite the transfusion of 2 units of packed RBCs	106	REBOA	7/3	52.3 ± 19.8	50	9
					Non-REBOA	30/66
Fonseca (2022) [36]	Brazil	Retrospective	Systolic BP <90 mmHg and BE >−5 mmol/L	51	EF	23/19	NA	75	8
					Non-EF	6/3
					AE	4/4
					Non-AE	25/18
Li (2016) [37]	China	Quasi-randomized	Systolic BP <90 mmHg after administration of 4 units of red cells	56	AE	5/22	40 ± 9	59	8
					EPP	4/25	43 ± 13	56
Tai (2011) [38]	Hong Kong, China	Retrospective	Persistent systolic BP ≤90 mmHg after receiving ≥2000 mL intravenous crystalloid	24	AE	9/4	44.8 ± 24.7	63	9
					EPP	4/7	51.2 ± 19.0
Patterson (2022) [39]	United States	Retrospective	Systolic BP <90 mmHg	366	AE	27/156	37.4 ± 2.1	74	8
					EPP	40/143	37.3 ± 2.0	72
Ip (2014) [40]	Hong Kong, China	Retrospective	Persistent systolic BP ≤90 mmHg after receiving ≥2000 mL intravenous crystalloid	29	AE	2/1	42.0 ± 11.3	100	7
					EPP	8/18	46.3 ± 20.2	42
Duchesne (2019) [41]	United States	Retrospective	Systolic BP <90 mmHg, heart rate >120 beats per minute, or BE >−5	279	REBOA	1.613 (0.326–7.971)	40 ± 14	62	9
					EPP	0.959 (0.261–3.522)
Anand (2023) [4]	United States	Retrospective	Received 4 or more units of packed RBCs within 4 hours of presentation, and underwent at least 1 pelvic fracture hemorrhage control intervention. Lowest SBP <90 mmHg	1396	AE	0.62 (0.47–0.82)	47 ± 19	70	9
					EPP	243/416
					Non-EPP	258/479
					REBOA	61/65
					Non-REBOA	440/830
				1270	AE	218/434
					EPP	222/396
Kim (2022) [42]	Korea	Retrospective	SBP <90 mmHg or SBP >90 mmHg but requiring bolus infusions and/or vasopressor drugs and/or admission base excess (BE) >−5 mmol/L and/or shock index >1 and/or transfusion requirement of at least 4–6 units of packed RBCs within the first 24 h	97	AE	9/23	NA	53	8
					Non-AE	28/37
					EPP	19/26
					Non-EPP	18/34
					EF	5/14
					Non-EF	32/46
				75	AE	12/26	56.7 ± 21.1	40
					EPP	15/22	58.9 ± 20.2	65