Table 1. Characteristics of included studies.

Author, Year, (Location), Indexed source, Study Design, [Reference Number]	Study Setting and study period	Study population	Inclusion criteria	Exclusion criteria	Proportion of patients with SBT≤90 mmHg (N/1000)	Main findings	Symptoms and Etiology	NOS/STROBE Score
Jones et al. 2004 (USA) Embase, PubMed and Cinahl Case-Control [32]	Prehospital 4 months (1995–2000)	14,379 patients assessed by EMS, N = 273, SBT≤90 mmHg	Age > 17 years, SBT<100 mmHg during transport and 1 or more of 10 predefined symptoms of circulatory insufficiency	Trauma transports	19	Out of hospital hypotension showed higher inhospital mortality	*	7/19
Jones et al. 2006 (USA) Embase, PubMed and Cinahl Cohort Study [30]	Emergency Department 12 months (2004–2005)	113,000 patients assessed in the ED, N = 398, SBP≤90 mmHg	Age>17 years, SBP<100 mmHg and admission to the hospital from the ED	(1) Trauma in the past 24 hour, (2) Direct admission or transfer from another facility or no evaluation in the ED, (3) No vital signs measured	4	Hypotension showed increased risk of death during hospitalization	*	7/19
Merz et al. 2011 (Switzerland) Embase and Pubmed Cohort Study [45]	Emergency Department 7 months (2007–2008)	15,939 patients assessed in the ED, N = 202, SBP≤90 mmHg	Age>15 years, All ED patients	Patients treated on an outpatient basis	13	Vital signs abnormilities are independent predictors of hospital mortality	Etiology	5/19
Poloujadoff et al. 2006 (France) Embase and Pubmed Cohort Study [46]	Prehospital 12 months (2002–2003)	10,291 patients assessed by EMS, N = 131, SBP≤90 mmHg	Non-palpable radial pulse and unrecordable blood pressure at clinical presentation	Patients with cardiac arrest, arterial disease or acute limb ischaemia	9	Conditions associated with mortality; Cardiac arrest, Age, Glasgow Coma Scale	Etiology	6/12
Seymour et al. 2013 (USA) Embase, PubMed and Cinahl Cohort Study [31]	Prehospital 48 months (2002–2006)	154,644 patients assessed by EMS, N = 8,484, SBP≤90 mmHg	Nontraumatic, noncardiac arrest in whom a physical exam was performed by EMS personal	Age<18 years, Patients with missing SBP measurements, or SBP = 0 or SBP>300 mm Hg	19.5	SBP is a modest predictor of 30-day mortality	Etiology	8/20
Wang et al. 2011 (USA) Embase, PubMed and Cinahl Cross-sectional study [44]	Prehospital 36 months (2006–2008)	3,327,306 patients assessed by EMS, N = 39,424, SBP≤90 mmHg	SBP<80 mmHg, Special screening criteria designed for identification of shock	EMS without patient contact, Age<18 years, patients classified as dead on EMS arrival and cardiac arrest	9.5	39,424 (91.80%) presented with medical conditions and 3,517 (8.19%) with traumatic conditions	Symptoms	5/18

*Not assessed as objective in study.

SBP: Systolic Blood Pressure, EMS: Emergency Service Systems