Table 2

Summary of characteristics for included studies

Study	Setting	Mean age of EMS patients (years)	n, EMS treatment group	% female EMS patients	Culprit opioid	Intervention	Primary outcome	Secondary outcome	Deaths within 48 hours
Levine et al 7	US EMS/LAFD	41	205	13	Heroin	Naloxone with release	Death within 24 hours	Death with in 30 days	1
Boyd et al 6	Helskinki EMS	26	71	17.2	Heroin	Naloxone with release	Death within 12 hours	Rebound toxicity	0
Rudolph et al 10	Copenhagen MECU	–	2241	–	Heroin/morphine	Naloxone with release	Death within 48 hours	Death likely to rebound toxicity	3
Vilke et al 9	US EMS/SDFD	39.8	317	16.3	Heroin	Naloxone with release	Death within 12 hours	N/A	0
Vilke et al 13	US EMS/SDFD	37.7	998	16.7	Heroin	Naloxone with release	Death within 12 hours	N/A	0
Wampler et al 14	US EMS/SAFD	38	552	28	Heroin/methadone	Naloxone with release	Death within 48 hours	Death with in 30 days	0
Heyerdahl et al 26	Oslo EMS, outpatient clinic and ED	34	528	31	Heroin	Naloxone with release	Death due to rebound in 1 week	N/A	0

ED, emergency department; EMS, emergency medical service; LAFD, Los Angeles Fire Department; MECU, Mobile Emergency Care Unit; SAFD, San Antonio Fire Department; SDFD, San Diego Fire Department. N/A, not applicable.