The global survival rate among adult out-of-hospital cardiac arrest patients who received cardiopulmonary resuscitation: a systematic review and meta-analysis
verfasst von:
Shijiao Yan, Yong Gan, Nan Jiang, Rixing Wang, Yunqiang Chen, Zhiqian Luo, Qiao Zong, Song Chen, Chuanzhu Lv
To quantitatively summarize the available epidemiological evidence on the survival rate of out-of-hospital cardiac arrest (OHCA) patients who received cardiopulmonary resuscitation (CPR).
Methods
We systematically searched the PubMed, Embase, and Web of Science databases, and the references of retrieved articles were manually reviewed to identify studies reporting the outcome of OHCA patients who received CPR. The overall incidence and outcome of OHCA were assessed using a random-effects meta-analysis.
Results
A total of 141 eligible studies were included in this meta-analysis. The pooled incidence of return of spontaneous circulation (ROSC) was 29.7% (95% CI 27.6–31.7%), the rate of survival to hospital admission was 22.0% (95% CI 20.7–23.4%), the rate of survival to hospital discharge was 8.8% (95% CI 8.2–9.4%), the pooled 1-month survival rate was 10.7% (95% CI 9.1–13.3%), and the 1-year survival rate was 7.7% (95% CI 5.8–9.5%). Subgroup analysis showed that survival to hospital discharge was more likely among OHCA patients whose cardiac arrest was witnessed by a bystander or emergency medical services (EMS) (10.5%; 95% CI 9.2–11.7%), who received bystander CPR (11.3%, 95% CI 9.3–13.2%), and who were living in Europe and North America (Europe 11.7%; 95% CI 10.5–13.0%; North America: 7.7%; 95% CI 6.9–8.6%). The survival to discharge (8.6% in 1976–1999 vs. 9.9% in 2010–2019), 1-month survival (8.0% in 2000–2009 vs. 13.3% in 2010–2019), and 1-year survival (8.0% in 2000–2009 vs. 13.3% in 2010–2019) rates of OHCA patients who underwent CPR significantly increased throughout the study period. The Egger’s test did not indicate evidence of publication bias for the outcomes of OHCA patients who underwent CPR.
Conclusions
The global survival rate of OHCA patients who received CPR has increased in the past 40 years. A higher survival rate post-OHCA is more likely among patients who receive bystander CPR and who live in Western countries.
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Abkürzungen
AED
Automated external defibrillator
CI
Confidence interval
CPR
Cardiopulmonary resuscitation
EMS
Emergency medical services
OHCA
Out-of-hospital cardiac arrests
ROSC
Return of spontaneous circulation
Background
Out-of-hospital cardiac arrest (OHCA) is a major public health challenge, with an average global incidence among adults of 55 OHCAs per 100,000 person-years. [1] In China, there are more than 230 million people with cardiovascular disease, and 550,000 individuals experience cardiac arrest every year [2]. Worldwide, survival after OHCA remains poor [3]. In China, the survival rate of OHCA is less than 1% [4]. Early initiation, good cardiopulmonary resuscitation (CPR) quality, and the use of an automated external defibrillator (AED) significantly improved survival and long-term outcomes in survivors of OHCA [2, 5‐7].
Many studies have been conducted to estimate the survival rate among OHCA patients who received CPR in different regions of the world [4, 8‐13]. However, the results were inconsistent across studies. The purpose of this systematic review and meta-analysis was to estimate the overall incidence of the return of spontaneous circulation (ROSC), the survival to admission rate, the survival to discharge rate, the 1-month survival rate, and the 1-year survival rate of patients after OHCA who received CPR worldwide.
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Methods
This systematic review and meta-analysis adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [14] and the Meta-analysis of Observational Studies in Epidemiology (MOOSE) checklist [15].
Search strategy
Studies that reported survival rates among OHCA patients who underwent CPR were identified from the PubMed, Embase, and Web of Science databases from their inception to February 2019. The search terms were “out-of-hospital cardiac arrest” or “out-of-hospital ventricular fibrillation/ventricular tachycardia/asystole/pulseless electrical activity” or “cardiopulmonary resuscitation” or “CPR” or “mouth to mouth” or “resuscitation” or “resuscitation orders” or “survival” or “survival rate” or “mortality” or “sudden cardiac death”. Only articles published in English were considered. Additionally, we manually reviewed the references listed in the retrieved articles to identify additional pertinent publications.
Inclusion criteria and exclusion criteria
Studies were included if they met the following eligibility criteria: (1) the study design was based on the Utstein-style reporting guidelines; (2) the study population was composed of adults, which included any study in which less than 20% of study population were pediatric patients (age < 18 years); (3) the outcome variables were at least one of the following: ROSC, survival to admission rate, survival to hospital discharge rate, 1-month survival rate, and 1-year survival rate; (4) cardiac arrest happened outside the hospital; and (5) the study design was prospective, retrospective, or interventional. Reviews, letters, editorials, guidelines, and case reports were excluded. When multiple publications were produced using the same study population, the most recent and informative paper was included.
Data extraction
Two independent reviewers (YG and NJ) performed the data extraction. The following data were extracted from the studies: the first author’s name, region of population, year of publication, sex, number of cardiac arrests and survivors, cardiac arrest witness type, provision of CPR, and origin of cardiac arrest. The rate of survival to hospital discharge was considered the primary outcome; ROSC, the rate of survival to hospital admission, 1-month survival rate and 1-year survival rate were also analyzed as outcome variables. Any disagreements between the investigators were discussed, and an agreement was reached through consensus.
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Statistical analysis
A random-effects model was used to estimate the survival rates among OHCA patients who received CPR [16]. Studies that reported the survival outcomes of OHCA patients who received CPR (ROSC, survival to admission rate, survival to discharge rate, 1-month survival rate, and 1-year survival rate) were treated as independent reports.
Statistical heterogeneity across studies was assessed with the I2 statistic, where values of 25%, 50%, and 75% represented the cut-off points for low, moderate, and high levels of heterogeneity, respectively [17]. Publication bias was evaluated with funnel plots and Egger’s test [18]. Subgroup analyses stratified by sex, study location, study period, origin of OHCA, CPR type, and cardiac arrest witness type were conducted to investigate potential sources of heterogeneity across subgroups and examine the robustness of the primary results. We performed sensitivity analyses by omitting one study at a time to assess the influence of any single study on the pooled survival rate estimates. All statistical analyses were conducted with STATA V.12.0 (StataCorp, College Station, TX). All tests were two-tailed with a significance level of 0.05.
Results
Study selection
The process of study selection, identification, and inclusion using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow diagram is presented in Fig. 1. Initially, 5502 articles were retrieved from the PubMed, Embase, and Web of Science databases. In addition, we identified 13 articles by manually searching the reference lists of the retrieved articles. After removing 915 duplicate articles, we further excluded 4371 articles based on the titles and abstracts, including 336 nonhuman studies and 280 reviews, editorials, letters, guidelines or case reports. A total of 229 articles were selected for further full texts assessment. After retrieving the full-text for evaluation in detail, 88 articles were excluded because their study populations were pediatric patients, their primary outcome focused on the neurological survival rate or they were multiple publications produced using the same study population. Finally, a total of 141 studies were included in the present meta-analysis. The references of the studies included in the meta-analysis are listed in the Additional file 1.
Fig. 1
Flow chart of relevant study identification in relation to outcomes of OHCA who underwent CPR
×
Characteristics and quality of the studies included
The characteristics of the 141 included studies are shown in Supplementary Table 1. These studies were conducted on 4 continents. Fifty-six studies were conducted in Europe, 48 in North America, 29 in Asia, 6 in Oceania, and two in both Europe and North America. A total of 31 studies reported the survivors and study population stratified by sex. The year of publication ranged from 1976 to 2019. In total, 4,610,669 OHCA patients who underwent CPR were involved in this study. We included 62 studies that reported the incidence of ROSC, 88 studies that explored the rate of survival to admission, 103 studies that assessed the rate of survival to discharge, 33 studies that investigated the 1-month survival rate, and 22 studies that reported the 1-year survival rate. Nineteen studies included pediatric patients, but less than 20% of study population was younger than 18 years.
ROSC
In this study, 62 studies with 74 reports reported the outcome of ROSC in OHCA patients who underwent CPR. From the random-effects meta-analysis, we found that the pooled incidence of ROSC among OHCA patients was 29.7% (95% CI, 27.6–31.7%) with significant heterogeneity across studies (I2 = 99.9%, P < 0.001).
Subgroup analyses showed significant differences in the incidence of prehospital ROSC by study location, the provider of CPR, and study period (Table 1). With regard to study location, Oceania had the highest incidence of ROSC (38.6%; 95% CI 22.9–54.2%), followed by Europe (36.7%; 95% CI 32.4–40.9%). Asia had the lowest incidence of ROSC (22.1%; 95% CI 18.1–26.0%). Regarding the provider of CPR, the incidence of ROSC was the highest among OHCA patients who had received CPR from emergency medical services (EMS) (36.3%; 95% CI 23.8–48.9%).
Table 1
The incidence of ROSC, survival to admission, survival to discharge, 1 month survival, and 1 year survival: the overall estimates and subgroup analyses
No. of reports
Survivors
OHCA cases
Proportion (%)
95%CI
I2
P value for heterogeneity
ROSC*
74
203,084
1,560,830
29.7
27.6 to 31.7
99.90%
< 0.001
Sex
Men
2
242
856
28.9
24.2 to 33.6
43.4%
0.184
Women
2
151
478
31.6
27.4 to 35.8
0.00%
0.542
Combined
70
202,691
1,559,496
29.7
27.6 to 31.8
99.90%
< 0.001
Study location
Europe
32
4166
12,274
36.7
32.4 to 40.9
96.10%
< 0.001
Asia
17
186,060
1,500,110
22.1
18.1 to 26.0
100.00%
< 0.001
North America
20
6981
32,520
24.3
19.7 to 28.9
99.10%
< 0.001
Oceania
5
5877
15,926
38.6
22.9 to 54.2
99.20%
< 0.001
Study period
1976–1999
25
3706
15,429
34.2
28.0 to 40.4
98.70%
< 0.001
2000–2009
30
4091
17,159
28.3
23.9 to 32.7
98.00%
< 0.001
2010–2019
19
195,287
1,528,242
27.5
23.6 to 31.3
100.00%
< 0.001
CPR type
Bystander CPR
17
138,149
863,978
26.3
20.9 to 31.8
100.00%
< 0.001
EMS CPR
15
45,505
624,496
36.3
23.8 to 48.9
99.50%
< 0.001
Unspecific CPR
42
19,430
72,356
29.6
25.9 to 33.3
99.30%
< 0.001
Origin of OHCA
Cardiac etiology
49
30,531
143,831
33.9
30.1 to 37.7
99.50%
< 0.001
Non-traumatic
14
7652
33,318
21.5
16.2 to 26.8
99.20%
< 0.001
All patients
11
164,901
1,383,681
23.3
18.3 to 28.3
100.00%
< 0.001
Others
NA
NA
NA
NA
NA
NA
NA
Witnessed type
Witnessed
31
106,894
440,281
36.4
30.6 to 42.2
99.90%
< 0.001
Not witnessed
1
34
93
36.6
26.8 to 46.4
0.00%
< 0.001
Mixed
36
95,828
1,119,248
23.7
22.2 to 25.3
99.80%
< 0.001
Unspecific events
6
328
1208
28.2
18.6 to 37.7
91.30%
< 0.001
Survival to admission†
122
55,026
377,727
22.0
20.7 to 23.4
99.4%
< 0.001
Sex
Men
7
564
2829
20.3
16.3 to 24.3
81.00%
< 0.001
Women
7
254
1021
23.4
17.8 to 29.1
72.60%
< 0.001
Combined
108
54,208
373,877
22.1
20.6 to 23.5
99.40%
< 0.001
Study location
Europe
52
20,987
123,024
25.7
23.9 to 27.6
98.30%
< 0.001
Asia
27
23,551
203,283
15.6
13.2 to 18.0
99.70%
< 0.001
North America
39
5504
35,183
20.5
18.1 to 22.9
97.50%
< 0.001
Oceania
4
4984
16,237
33.5
21.7 to 45.3
98.90%
< 0.001
Study period
1976–1999
59
5704
33,083
22.4
20.0 to 24.8
97.30%
< 0.001
2000–2009
38
18,433
106,336
25.1
22.9 to 27.3
98.50%
< 0.001
2010–2019
25
30,889
238,308
17.2
14.4 to 19.9
99.80%
< 0.001
CPR type
Bystander CPR
21
6660
44,028
22.8
18.8 to 26.8
99.10%
< 0.001
EMS CPR
23
2043
7657
25.5
19.7 to 31.2
97.40%
< 0.001
Unspecific CPR
78
46,323
326,042
21.1
19.5 to 22.7
99.50%
< 0.001
Origin of OHCA
Cardiac etiology
66
22,682
143,612
23.5
21.2 to 25.9
99.50%
< 0.001
Non-traumatic
38
17,293
142,532
19.3
17.5 to 21.2
98.60%
< 0.001
All patients
11
13,953
86,443
20.4
17.1 to 23.7
99.10%
< 0.001
Others
7
1098
5140
23.6
19.4 to 27.7
91.50%
< 0.001
Witnessed type
Witnessed
37
12,027
88,992
23.2
20.3 to 26.1
99.60%
< 0.001
Not witnessed
1
23
93
24.7
15.9 to 33.5
0.00%
< 0.001
Mixed
75
42,630
286,470
21.6
20.1 to 23.1
99.10%
< 0.001
Unspecific events
9
346
2172
19.2
14.5 to 23.9
84.30%
< 0.001
Survival to discharge‡
168
20,946
267,862
8.8
8.2 to 9.4
97.60%
< 0.001
Sex
Men
22
1576
26,666
7.4
6.2 to 8.7
93.60%
< 0.001
Women
21
723
13,570
7.2
5.6 to 8.7
91.70%
< 0.001
Combined
125
18,647
227,626
9.3
8.5 to 10.0
97.90%
< 0.001
Study location
Europe
59
3607
33,673
11.7
10.5 to 13.0
92.70%
< 0.001
Asia
16
5329
86,333
4.5
3.1 to 5.9
98.60%
< 0.001
North America
89
10,115
131,564
7.7
6.9 to 8.6
97.60%
< 0.001
Oceania
4
1895
16,292
16.2
5.9 to 26.5
99.10%
< 0.001
Study period
1976–1999
80
4851
59,816
8.6
7.7 to 9.5
95.00%
< 0.001
2000–2009
63
5612
78,018
8.6
7.5 to 9.6
97.20%
< 0.001
2010–2019
25
10,483
130,028
9.9
8.4 to 11.4
99.10%
< 0.001
CPR type
Bystander CPR
35
4493
39,974
11.3
9.3 to 13.2
97.40%
< 0.001
EMS CPR
27
1754
14,108
10.7
8.2 to 13.2
95.80%
< 0.001
Unspecific CPR
106
14,699
213,780
7.7
7.0 to 8.3
97.40%
< 0.001
Origin of OHCA
Cardiac etiology
84
11,765
132,292
10.0
9.1 to 10.9
97.00%
< 0.001
Non-traumatic
62
7117
111,171
7.0
6.2 to 7.9
97.70%
< 0.001
All patients
13
879
9826
8.3
5.4 to 11.2
96.00%
< 0.001
Others
9
1185
14,573
10.1
8.3 to 12.0
89.50%
< 0.001
Witnessed type
Witnessed
44
8967
97,069
10.5
9.2 to 11.7
97.60%
< 0.001
Not witnessed
3
16
324
4.4
1.4 to 7.4
40.00%
0.189
Mixed
118
11,951
170,341
8.2
7.5 to 8.9
97.20%
< 0.001
Unspecific events
3
12
128
8.9
4.0 to 13.8
0.00%
0.705
One-month survival§
54
247,999
2,362,223
10.7
9.1 to 12.3
99.9%
< 0.001
Sex
Men
4
3968
46,831
8.0
5.2 to 10.9
99.10%
< 0.001
Women
4
2477
18,891
9.5
3.2 to 15.8
99.50%
< 0.001
Combined
45
241,554
2,296,501
11.0
9.3 to 12.8
100%
< 0.001
Study location
Europe
28
25,371
292,473
9.0
7.6 to 10.3
99.50%
< 0.001
Asia
21
222,285
2,066,705
12.8
10.0 to 15.5
100%
< 0.001
North America
2
41
623
6.5
4.6 to 8.5
0.00%
0.415
Oceania
3
302
2422
16.0
8.4 to 23.7
96.10%
< 0.001
Study period
1976–1999
NA
NA
NA
NA
NA
NA
NA
2000–2009
28
17,304
219,965
8.0
6.7 to 9.3
99.3%
< 0.001
2010–2019
26
230,695
2,142,258
13.3
10.9 to 15.7
100%
< 0.001
CPR type
Bystander CPR
25
161,386
1,074,767
12.8
9.0 to 16.7
100%
< 0.001
EMS CPR
6
37,308
666,669
12.3
8.6 to 16.0
99.70%
< 0.001
Unspecific CPR
23
49,305
620,787
7.9
7.1 to 8.7
99.20%
< 0.001
Origin of OHCA
Cardiac etiology
26
21,262
208,631
10.5
9.1 to 12.0
99.10%
< 0.001
Non-traumatic
1
23
342
6.7
4.1 to 9.3
0
< 0.001
All patients
27
226,714
2,153,250
10.8
8.5 to 13.1
100%
< 0.001
Others
NA
NA
NA
NA
NA
NA
NA
Witnessed type
Witnessed
27
169,542
1,055,935
13.2
10.3 to 16.1
99.9%
< 0.001
Not witnessed
NA
NA
NA
NA
NA
NA
NA
Mixed
27
78,457
1,306,288
8.3
7.4 to 9.1
99.7%
< 0.001
Unspecific events
NA
NA
NA
NA
NA
NA
NA
One-year survival¶
27
3791
42,027
7.7
5.8 to 9.5
97.5%
< 0.001
Sex
Men
1
13
320
4.1
1.9 to 6.3
0.00%
< 0.001
Women
1
14
219
6.4
3.2 to 9.6
0.00%
< 0.001
Combined
25
3764
41,488
7.9
5.9 to 9.8
97.7%
< 0.001
Study location
Europe
16
3378
35,604
9.2
6.4 to 12.0
98.2%
< 0.001
Asia
3
118
2504
5.3
2.7 to 8.0
87.8%
< 0.001
North America
7
96
2190
4.0
2.8 to 5.3
51.2%
0.056
Oceania
1
199
1729
11.5
10.0 to 13.0
0.0%
< 0.001
Study period
1976–1999
10
407
3517
8.5
4.1 to 12.8
96.6%
< 0.001
2000–2009
14
479
7496
6.0
4.3 to 7.6
89.0%
< 0.001
2010–2019
3
2905
31,014
12.3
5.4 to 19.3
99.6%
< 0.001
CPR type
Bystander CPR
2
1579
10,805
12.3
6.4 to 18.1
79.6%
0.027
EMS CPR
3
17
480
3.2
0.5 to 6.0
64.6%
0.059
Unspecific CPR
22
2195
30,742
7.6
6.1 to 9.2
95.2%
< 0.001
Origin of OHCA
Cardiac etiology
25
3763
41,493
7.9
6.0 to 9.9
97.6%
< 0.001
Non-traumatic
1
24
338
7.1
4.4 to 9.8
0.0%
< 0.001
All patients
NA
NA
NA
NA
NA
NA
NA
Others
1
4
196
2.0
0 to 4.0
0.0%
< 0.001
Witnessed type
Witnessed
12
283
5765
5.3
4.0 to 6.5
77.9%
< 0.001
Not witnessed
NA
NA
NA
NA
NA
NA
NA
Mixed
15
3508
36,262
9.0
6.1 to 11.9
98.3%
< 0.001
Unspecific events
NA
NA
NA
NA
NA
NA
NA
Note: CI confidence interval, CPR cardiopulmonary resuscitation, EMS emergency medical services, NA not available, OHCA out-of-hospital cardiac arrests, ROSC return of spontaneous circulation
*Two studies reported their results by study location, 2 studies reported their results by sex, 4 studies reported their results by CPR type, 2 studies reported their results by witness type, and 1 study reported their results by OHCA type; therefore, there were 74 reports from 62 studies
†Four studies reported their results by study location, 7 studies reported their results by sex, 7 studies reported their results by CPR type, 2 studies reported their results by witness type, and 1 study reported their results by OHCA type; therefore, there were 122 reports from 88 studies
‡Three studies reported their results by study location, 21 studies reported their results by sex, 16 studies reported their results by CPR type, 1 study reported their results by witness type, and 2 studies reported their results by OHCA type; therefore, there were 168 reports from 103 studies
§Four studies reported their results by sex, 4 studies reported their results by CPR type, 2 studies reported their results by OHCA type, and 1 study reported their results by year; therefore, there were 54 reports from 33 studies
¶One study reported their results by sex, 2 studies reported their results by CPR type, and 1 study reported their results by witness type; therefore, there were 27 reports from 22 studies
Survival to admission
A total of 88 studies with 122 reports estimated the incidence of survival to admission of OHCA patients who underwent CPR. From the random-effects meta-analysis, an incidence of 22.0% (95% CI 20.7–23.4%) for survival to admission was estimated globally among OHCA patients who received CPR.
With regard to study location, Oceania had the highest incidence (33.5%; 95% CI 21.7–45.3%), followed by Europe (25.7%; 95% CI 23.9–27.6%), North America (20.5%; 95% CI 18.1–22.9%), and Asian countries (15.6%; 95% CI 13.2–18.0%).
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Survival to discharge
One hundred and three studies with 168 reports investigated the rate of survival to discharge of OHCA patients who underwent CPR. From the random-effects meta-analysis, an incidence of 8.8% (95% CI 8.2–9.4%) for survival to discharge was estimated globally among OHCA patients, and there was high heterogeneity across studies (P < 0.001; I2 = 97.6%) (Table 1). The rate of survival to discharge of OHCA patients who received CPR increased from 8.6% (95% CI 7.7–9.5%) in 1976–1999 to 9.9% (95% CI 8.4–11.4%) in 2010–2019.
Subgroup analyses showed significant differences in the survival rate by study location and provider of CPR. Across the study locations, Oceania had the highest survival rate (16.2%; 95% CI 5.9–26.5%), followed by Europe (11.7%; 95% CI 10.5–13.0%), North America (7.7%; 95% CI 6.9–8.6%), and Asia (4.5%; 95% CI 3.1–5.9%). Regarding the provider of CPR, the survival rate was relatively higher among patients who received bystander CPR (11.3%; 95% CI 9.3–13.2%).
One-month survival rate
In total, 33 studies with 54 reports investigated the 1 month survival rate of OHCA patients who underwent CPR. From the random-effects meta-analysis, an incidence of 10.7% (95% CI 9.1–12.3%) for 1-month survival was estimated globally among OHCA patients who had received CPR, and there was high heterogeneity among the studies (P < 0.001; I2 = 99.9%).
Subgroup analyses showed significant differences in 1-month survival by study location and study period. Across the study locations, Oceania had the highest survival rate (16.0%; 95% CI 8.4–23.7%), followed by Asia (12.8%; 95% CI 10.0–15.5%), Europe (9.0%; 95% CI 7.6–10.3%), and North America (6.5%; 95% CI 4.6–8.5%). Across the study periods, the 1-month survival rate increased from 8.0% (95% CI, 6.7–9.3%) in 2000–2009 to 13.3% (95% CI 10.9–15.7%) in 2010–2019.
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One-year survival rate
Twenty-seven reports from 22 studies investigated the 1 year survival rate of OHCA patients who underwent CPR. From the random-effects meta-analysis, an incidence of 7.7% (95% CI 5.8–9.5%) for 1-year survival was estimated globally among OHCA patients who received CPR, and there was high heterogeneity among the studies (P < 0.001; I2 = 97.5%).
Subgroup analyses showed significant differences in 1-year survival by study location and study period. Across the study locations, Oceania had the highest survival rate (11.5%; 95% CI 10.0–13.0%), followed by Europe (9.2%; 95% CI 6.4–12.0%), Asia (5.3%; 95% CI 2.7–8.0%), and North America (4.0%; 95% CI 2.8–5.3%). Across the study periods, the 1-year survival rate increased from 6.0% (95% CI 4.3–7.6%) in 2000–2009 to 12.3% (95% CI 5.4–19.3%) in 2010–2019. Regarding the provider of CPR, the survival rate was relatively higher among patients who received bystander CPR (12.3%; 95% CI 6.4–18.1%).
Sensitivity analyses
The exclusion of studies with sample sizes less than 100 yielded pooled incidences of 29.0% (95% CI 26.8–31.2%, P < 0.001), 21.6% (95% CI 20.1–23.0%, P < 0.001), 8.6% (95% CI 8.0–9.2%, P < 0.001), 10.8% (95% CI 9.2–12.4%, P < 0.001), and 7.6% (95% CI 5.7–9.5%, P < 0.001) for ROSC, survival to hospital admission, survival to hospital discharge, 1-month survival, and 1-year survival, respectively. Thus, the survival rate did not change significantly when the observations with sample sizes less than 100 were excluded, which indicated that studies with small sample sizes did not influence the overall result. Furthermore, after the exclusion of these studies (n = 19) including pediatric patients, the pooled survival rates for ROSC, survival to hospital admission, survival to hospital discharge, 1-month survival, and 1-year survival were 30.5% (95% CI 26.7–34.3%, P < 0.001), 21.8% (95% CI 20.4–23.3%, P < 0.001), 9.7% (95% CI 8.9–10.5%, P < 0.001), 10.1% (95% CI 7.9–12.3%, P < 0.001), and 7.6% (95% CI 5.6–9.6%, P < 0.001), respectively.
Sensitivity analyses were performed by omitting each study in turn and combining the results of the remaining included studies. The overall summary survival rates for ROSC, survival to admission, survival to discharge, and the 1-month and 1-year survival rates did not alter substantially. The pooled survival rates derived from the sensitivity analyses for ROSC ranged from 28.8% (95% CI 27.5–30.1%) to 30.3% (95% CI 27.6–33.0%), those for survival to hospital admission ranged from 21.7% (95% CI 20.4–23.1%) to 22.2% (95% CI 20.8–23.7%), those for survival to hospital discharge ranged from 8.6% (95% CI 8.0–9.2%) to 8.9% (95% CI 8.2–9.5%), those for 1-month survival ranged from 10.1% (95% CI 8.5–11.7%) to 10.9% (95% CI 9.3–12.4%), and those for 1-year survival ranged from 6.9% (95% CI 5.2–8.6%) to 7.9% (95% CI 6.0–9.8%).
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Publication bias
The funnel plot was symmetrical for the meta-analysis of the incidence of ROSC, survival to hospital admission, survival to hospital discharge, 1-month survival, and 1-year survival in OHCA patients who received CPR (see Figs. 2, 3, 4, 5, and 6). The Egger’s test revealed no evidence of publication bias among the studies that reported the incidence of ROSC, survival to admission, survival to hospital discharge, and 1-year survival rate (Egger’s P = 0.362 for ROSC; Egger’s P = 0.128 for survival to admission; Egger’s P = 0.112 for survival to hospital discharge; Egger’s P = 0.168 for 1-year survival). However, for the 1-month survival among OHCA patients who underwent CPR, we found that Egger’s test revealed evidence of publication bias across studies (Egger’s P < 0.05).
Fig. 2
Funnel plot for the incidence of ROSC among OHCA patients who underwent CPR
Fig. 3
Funnel plot for the incidence of survival to admission among OHCA patients who underwent CPR
Fig. 4
Funnel plot for the incidence of survival to discharge among OHCA patients who underwent CPR
Fig. 5
Funnel plot for the 1 month survival rate among OHCA patients who underwent CPR
Fig. 6
Funnel plot for the 1 year survival rate among OHCA patients who underwent CPR
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Discussion
This is the first comprehensive systematic review and meta-analysis bringing together 40 years of research to estimate the incidence of ROSC, rate of survival to admission, rate of survival to discharge, 1-month survival rate, and 1-year survival rate among OHCA patients who received CPR worldwide. We found that the pooled incidence of ROSC, and survival to admission, survival to discharge, 1-month survival, and 1-year survival rates were 29.7%, 22.0%, 8.8%, 10.7%, and 7.7%, respectively. In addition, much lower rates of the incidence of ROSC, survival to admission, and survival to discharge were observed across Asian countries and much higher survival to discharge, 1-month survival, and 1-year survival rates were found among OHCA patients who had received bystander CPR. Finally, survival to discharge among OHCA patients who underwent CPR significantly improved over the 40-year period.
Two previous studies published in 2010 [19] and 2013 [20] investigated the survival rate of OHCA patients who received CPR. The results of this current meta-analysis generally concur and further complement the findings of a previous review in several important aspects. Van de Glind et al. [20] reported that the pooled survival to discharge among patients > 70 years of age was 4.1% (95% CI 3.0–5.6%), which was lower than that in the present study (8.8%: 95% CI 8.2–9.4%). One possible reason was that there were differences in the study population and sample size. The review by Van de Glind and colleagues included only 23 studies among older patients aged > 70 years. However, our study population included all age groups. Several studies showed that increasing age was significantly associated with worse survival [21‐23]. Additionally, their review did not fully investigate other subgroups or perform sensitivity analyses. Sasson et al. [19] found that the pooled survival to hospital discharge rate was 7.6% (95% CI 6.7–8.4%). However, 62 studies were not included in their analysis because their search time was limited to 2008, which may have led to overestimation of the survival rate. In addition, our review performed more detailed subgroup analyses (stratified by sex, study location, study period, type of OHCA, type of CPR, and type of cardiac arrest witness) to test the robustness of the results and explore the potential heterogeneity.
Our subgroup analyses led to two valuable findings. First, much lower rates of ROSC, survival to admission, and survival to discharge were observed in Asian countries than in European counties. These observed differences may in part reflect the differences in first registered arrhythmia as VT/VF, witnessed collapse, bystander CPR, and early defibrillation in various countries [4, 24]. These factors were significantly associated with the survival rates of OHCA patients [25‐27]. Another explanation is that compared with North America and Europe, and the popularization of bystander CPR has been relatively delayed in Asia; thus, the quality of bystander CPR might be lower in Asia. In addition, a previous study showed that the thresholds of EMS protocols for initiating resuscitation are lower in Asian countries, [1] which was likely to contribute to the differences in the survival rates.
We also found much higher rates of survival to discharge, 1 month survival, and 1 year survival among OHCA patients who received bystander CPR, which was consistent with the findings of previous studies [26, 28‐30]. This suggests that efforts, such as targeted CPR training to increase the bystander CPR rate, will have a substantial effect on improving the survival rates after OHCA [6, 31]. Thus, facilitating bystander CPR training is an important and effective measure that governments worldwide can implement to improve the outcome of OHCA patients.
Strengths and limitations
The present study has several strengths. First, this is the first study to date investigating the survival of OHCA patients worldwide. Second, based on the subgroup analysis, we showed that the survival to discharge rate was much lower in developing countries than in developed counties, and the ROSC and survival to discharge rates were decreasing. Finally, as the incidence of OHCA is increasing in modern society, the results of our study can not only serve as baseline data for the global assessment of OHCA prevention interventions (evidence-based region-specific guideline updates of CPR for OHCA) but also provide a reference for international comparisons.
Potential limitations in this study need to be acknowledged. A high degree of heterogeneity was observed in this meta-analysis. The heterogeneity across studies may result from differences in the EMS system, research method, samples, provider and quality of CPR (e.g., bystander CPR, EMS CPR), and Utstein definition. However, the sensitivity analyses and consistent results from various subgroup analyses suggested that the estimates were relatively robust, and the heterogeneity can be overestimated when studies with large sample sizes are pooled. Second, only those studies published in English were included in this meta-analysis and studies in other languages were omitted. Third, the literature searches were carried out in three databases, which may be considered a source of bias.
Suggestions for further research
More effort should be put into future research. First, more studies should be included to explore the predictors of survival of OHCA and investigate the associations between survival after OHCA and the predictors (age, sex, location of cardiac arrest, response time, CPR by bystander or EMS-physician-guided CPR, AED utilization). This would help elucidate the reasons for improved survival and the underlying mechanisms. Second, investigating the quality of life and cognitive and functional changes in survivors after OHCA will be valuable. Finally, more studies validating the cost-effectiveness of bystander CPR training or AED utilization are warranted.
Conclusion
In conclusion, this meta-analysis suggests that the rates of survival to discharge, 1 month survival, and 1 year survival are increasing among OHCA patients who receive CPR globally. Relatively lower survival to discharge rates were observed in Asian countries. Higher rates of survival to discharge, 1-month survival, and 1-year survival were found among OHCA patients who had their cardiac arrest witnessed by EMS or a bystander and who received bystander CPR.
We thank all the authors of the studies included in our meta-analysis.
Ethics approval and consent to participate
Ethical approval is not required for this systematic review.
Consent for publication
Not applicable.
Competing interests
The authors declare that they have no competing interests.
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The global survival rate among adult out-of-hospital cardiac arrest patients who received cardiopulmonary resuscitation: a systematic review and meta-analysis
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Shijiao Yan Yong Gan Nan Jiang Rixing Wang Yunqiang Chen Zhiqian Luo Qiao Zong Song Chen Chuanzhu Lv
