Aim 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 outcomes in dispatcher-assisted cardiopulmonary resuscitation (DA-CPR) is unclear.

Method Adults and cardiac OHCA received DA-CPR between 2013 and 2016 were analysed. The main exposure was DTI defined as the time interval from the call for ambulance to the detection 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 increase and three DTI groups; Short (0–90 s), Middle (91–180 s), and Long (181–1,200 s) groups.

Results Of 1 16 374 adults with an OHCA, 11 833 were finally analysed. Overall, the survival to discharge rate was 11.4%, and the good CPC rate was 8.0%. For good CPC, 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.

Conclusion A longer DTI in DA-CPR showed significantly lower good neurological recovery in witnessed and adult OHCA patients and 30 s delay was associated with 3% decrease of good CPC.

Conflict of interest None

Funding None