Introduction
We aimed to examine the effects of ethnicity and socioeconomic status (SES) on Out of Hospital Cardiac Arrest (OHCA) incidence and 30-day survival in Singapore. 

Methods
We analyzed data from the Singapore cohort of the Pan Asia Resuscitation Outcome Study (PAROS), a multi-center, prospective OHCA registry between April 2010 and December 2015. The Singapore Socioeconomic Disadvantage Index (SEDI) score was obtained for each case according to zip code and used as a surrogate for neighborhood SES. Age-adjusted OHCA incidence (cases/mid-year population) and Utstein survival were calculated by ethnicity and SES. Utstein survival was defined as the number of cardiac OHCA cases with initial rhythm of ventricular fibrillation witnessed by a bystander who survived 30-days or until hospital discharge—whichever occurred first. Logistic regression was used to investigate ethnicity and SES as predictors of 30-day survival and Utstein survival. 

Results
Our study population comprised 8900 patients: 6453 Chinese, 1472 Malays, and 975 Indians. The overall age-adjusted incidence ratios (95% CI) for Malay/Chinese and Indian/Chinese were 1.93 (1.83-2.04) and 1.95 (1.83-2.08) respectively. The overall age-adjusted incidence ratios (95% CI) for average/low and high/low SEDI group were 1.12 (0.95-1.33) and 1.29 (1.08-1.53) respectively.  Malay ethnicity showed smaller Utstein survival of 8.1% compared to Chinese (14.6%) and Indian (20.4%) [p=0.018]. Ethnicity approached statistical significance (p=0.072) in forward selection model of Utstein survival, while SEDI score and category were not significant (p>0.2 and p=0.349 respectively). 

Conclusion
We found the Malay and Indian community to be at higher risk of cardiac arrest compared to Chinese, and the Malay community is also at higher risk of subsequent mortality than the Chinese and Indian communities. These disparities were not explained by neighborhood socioeconomic disadvantage level. There might be an opportunity to investigate ethnic and cultural risk factors amenable for interventions in our community.

Ethnic and neighbourhood socioeconomic differences in the incidence and survival of Out-Of-Hospital Cardiac Arrest in Singapore