b'322021 CARES Annual Report Early CPROne of the critical interventions to achieving successful resuscitation is early CPR. If CPR is started before an ambulance arrives, the patients chances of survival dramatically increase. In 2021, bystander CPR was initiated on 40.2% of CARES patients. Of note, CARES excludes 911 Responder witnessed events as well as those that occurred in a nursing home or healthcare facility from our bystander CPR rate, as these are scenarios where we would expect CPR to be performed by a trained medical provider. Bystander CPR provision was strongly correlated with arrest witness status (Figure 13). Bystander CPR was initiated after 48.1% of bystander witnessed events, compared with 34.0% of unwitnessed events (p.0001). Figure 13. Bystander CPR provision by arrest witness status.Return of spontaneous circulation (ROSC) in the field, survival to hospital admission, and survival to hospital discharge were all strongly associated with receipt of bystander CPR (Figure 14). The survival to discharge rate for patients receiving bystander CPR (11.2%) was significantly (p.0001) higher than that of patients who did not receive bystander CPR (6.7%). Figure 14. Unadjusted survival outcomes after bystander CPR.'