Results

In total, 5087 OHCAs (292 per 100,000 person-years) were recorded by the Penang OHCA registry during the study period, of which EMS attempted resuscitation in 828 (16.3%) (Fig. 2). Table 1 displays descriptive characteristics of the included OHCAs stratified by whether or not EMS attempted resuscitation. The recorded OHCA cases were predominantly male (54.8%) with a median age of 73 (IQR 61–83) years. Compared to untreated patients, EMS-treated patients were more likely to be male and younger compared to untreated patients, and their arrests were more likely to have been witnessed by bystanders (47.2% vs 34.6%) or EMS personnel (9.1% vs 1.2%). The median EMS response time was 22 min [IQR 16–30]. The majority of patients were of either Chinese (52.2%) or Malay (33.0%) ethnicity and experienced their OHCA in homes (92.8%). EMS-treated OHCAs had bystander CPR performed in 43.5% of cases and an automated external defibrillator (AED) applied in 7.1% of cases. Over half of OHCAs with attempted resuscitation by EMS (60.1%) were transported to hospital, with return of spontaneous circulation and 30-day survival occurring in 10.3% and 1.3% of cases, respectively.

Variable | All records(N = 5087) | OHCA with EMS resuscitation attempt(n = 828) | OHCA without EMS resuscitation attempt(n = 4259) | p value | Missing, n (%)
Age in years, median [IQR] | 73 [61–83] | 63 [49–75] | 75 [64–84] | <0.001 | 29 (0.6)
Aged <18 years, n (%) | 33 (0.7) | 17 (2.1) | 16 (0.4) | <0.001 | 
Sex, n (%) |  |  |  | <0.001 | 6 (0.1)
Male | 2785 (54.8) | 565 (68.3) | 2220 (52.2) |  | 
Female | 2296 (45.2) | 262 (31.7) | 2034 (47.8) |  | 
Ethnicity, n (%) |  |  |  | <0.001 | 36 (0.7)
Chinese | 2639 (52.2) | 351 (42.6) | 2288 (54.1) |  | 
Malay | 1666 (33.0) | 311 (37.7) | 1355 (32.1) |  | 
Indian | 499 (9.9) | 116 (14.1) | 383 (9.1) |  | 
Other | 247 (4.9) | 46 (5.6) | 201 (4.8) |  | 
Public location, n (%) | 365 (7.2) | 148 (17.9) | 217 (5.1) | <0.001 | 1 (0.0)
Time of day, n (%) |  |  |  | 0.789 | 4 (0.1)
Daytime (08:00–15:59) | 2026 (39.9) | 321 (38.8) | 1705 (40.1) |  | 
Evening (16:00–23:59) | 1700 (33.4) | 283 (34.2) | 1417 (33.3) |  | 
Overnight (00:00–07:59) | 1357 (26.7) | 223 (27.0) | 1134 (26.6) |  | 
Day of week, n (%) |  |  |  | 0.345 | 0 (0.0)
Weekday (Monday-Friday) | 3596 (70.7) | 572 (69.3) | 3022 (71.0) |  | 
Weekend (Saturday-Sunday) | 1491 (29.3) | 254 (30.7) | 1237 (29.0) |  | 
Witnessed arrest, n (%) |  |  |  | <0.001 | 0 (0.0)
By bystander | 1866 (36.7) | 391 (47.2) | 1475 (34.6) |  | 
By EMS personnel | 126 (2.5) | 75 (9.1) | 51 (1.2) |  | 
Bystander CPR performed, n (%) | 397 (7.8) | 360 (43.5) | 37 (0.9) | <0.001 | 0 (0.0)
Bystander AED Applied, n (%) | 125 (2.5) | 59 (7.1) | 66 (1.5) | <0.001 | 0 (0.0)
EMS response time in minutes, median [IQR] | 21 [16–29] | 22 [16–30] | 22 [16–29.5] | 0.988 | 37 (0.7)
Initial shockable rhythm detected by EMS, n (%) | 52 (1.0) | 52 (6.3) | 0 (0.0) | <0.001 | 0 (0.0)
Mechanical CPR applied, n (%) | 95 (1.9) | 95 (11.5) | 0 (0.0) | <0.001 | 0 (0.0)
Transported to hospital, n (%) | 497 (9.8) | 497 (60.1) | 0 (0.0) | <0.001 | 1 (0.0)
Return of spontaneous circulation, n (%) | 84 (1.7) | 82 (10.3) | 0 (0.0) | <0.001 | 65 (1.3)
Survived event, n (%) | 26 (3.1) | 26 (3.1) | 0 (0.0) | <0.001 | 23 (0.5)
Survival to 30 days, n (%) | 11 (0.2) | 11 (1.3) | 0 (0.0) | <0.001 | 11 (0.2)