Design and rationale of the TANGO2 trial: A randomized controlled non-inferiority trial of bystander compression-only CPR versus standard CPR in out-of-hospital cardiac arrest

Rationale Bystander cardiopulmonary resuscitation (CPR) before emergency medical services arrival is associated with improved survival after out-of-hospital cardiac arrest (OHCA). Compression-only CPR (CO-CPR) is simpler to teach and perform, eliminates interruptions in chest compressions for rescue breaths, and has been associated with higher bystander CPR rates. For adults with OHCA of presumed medical etiology, clinical equipoise remains regarding the optimal CPR strategy for previously trained bystanders. Primary hypothesis Bystander CO-CPR is non-inferior to standard CPR (S-CPR) for 30-day survival in dispatch-assisted out-of-hospital cardiac arrest Design TANGO2 is an international, multicenter, randomized, open-label, non-inferior trial. Dispatchers randomize eligible cases 1:1 to CO-CPR or S-CPR via an integrated decision-support system. Protocol adherence is evaluated via systematic dispatch audio review. Per-protocol (PP) analysis is prespecified as the primary analysis, supported by modified intention-to-treat (mITT) analysis. Non-inferiority is defined as an absolute risk difference above -1.0 percentage points. Sites All Emergency Medical Dispatch Centers in Sweden and selected sites in Italy. Estimated Enrollment 3,260 per-protocol EMS-treated OHCA patients Enrollment dates Start date: 2017. Estimated completion date: December 2027. Current Status Enrolling. Trial registration ClinicalTrials.gov Identifier: NCT03981107, https://clinicaltrials.gov/study/NCT03981107 .