Effect of detection time interval for out-of-hospital cardiac arrest on outcomes in dispatcher-assisted cardiopulmonary resuscitation: A nationwide observational study

Abstract

Introduction: The association between the detection time interval (DTI) from the call for ambulance to the detection of out-of-hospital cardiac arrest (OHCA) by the dispatcher and the neurological outcome in dispatcher-assisted cardiopulmonary resuscitation (DA-CPR) is unclear. Methods: Adults who sustained OHCA with cardiac etiology received DA-CPR between 2013 and 2016 were analyzed. The main predictor was DTI defined as the time interval from the beginning of the emergency call to identification of OHCA by the dispatcher. The primary outcomes were the good cerebral performance category (CPC) 1 or 2. Multivariable logistic regression analysis was performed to calculate the adjusted odds ratio (AOR) and 95% confidence interval (CI) for outcomes, adjusting for potential confounders, by the 10- and 30-s DTI delay and three DTI groups; Short (0-90 s), Middle (91-180 s), and Long (181-1,200 s) groups. Interaction analysis for DTI and urbanization level (megacity with 10 million or more population in urban region, metropolis with 1 to 5 million population in urban region, and Rural province with less than 2 million population in urban, suburban, and rural region) was performed to compare the effect size of DTI group according to urbanization level. Results: Of 116,374 adults with an OHCA, 11,833 were finally analyzed. Overall, the number (%) of survival to discharge was 1380 (11.4%), and the good CPC was 945 (8.0%). For good cerebral performance category, the AOR (95% CIs) for good CPC was 0.99 (0.98-1.00) by 10-s DTI delay and 0.97 (0.95-0.99) by 30-s DTI delay. The AORs (95% CIs) for good CPC were 0.84 (0.71-1.00) for the Middle and 0.79 (0.66-0.96) for the Long DTI groups compared with Short DTI. The AORs (95% Cl) for good CPC compared with Short DTI group were 0.93 (0.68-1.27) by Middle DTI and 0.84 (0.59-1.20) by Long DTI in megacity, 0.60 (0.44-0.81) by Middle DTI and 0.60 (0.44-0.82) by Long DTI in metropolis, and 0.43 (0.31-0.60) by Middle DTI and 0.38 (0.26-0.56) by Long DTI in Rural province, respectively. Conclusion: A longer DTI in DA-CPR showed significantly lower good neurological recovery in adult patients with witnessed OHCA. A 30 s delay in DTI was associated with a 3% decrease of a good CPC score. The DTI effect on good CPC was significant in metropolis and Rural province while not in megacity region.