Delay Prior to Calling 9-1-1 Is Associated with Increased Mortality After Out-of-Hospital Cardiac Arrest

Abstract

Objective. We sought to characterize the collapse-to-9-1-1 call interval, to evaluate the frequency of pre–9-1-1 delay, andto assess whether delay is associated with decreased survival after out-of-hospital cardiac arrest (OHCA). Methods. This was a five-year prospective survey of bystanders to adult OHCA cases in which the victims were transported to seven local teaching hospitals in Michigan. Bystander data were obtained by telephone interview beginning two weeks after the event, andthrough review of emergency medical services (EMS) documents. Criteria for pre–9-1-1 delay were prospectively developed. Two paramedic reviewers were trained on these criteria andreviewed bystander andEMS data for each cardiac arrest case. Multivariate regression analysis was used to assess the independent impact of delay on survival. We collected common bystander andEMS OHCA demographics, as well as bystander description of events prior to the 9-1-1 call. Outcome was survival to hospital discharge. Results. During the study period we identified 1,004 OHCAs, for which 779 bystanders completed interviews. Of these interviews, 688 had adequate data for analysis. Raters showed moderate to strong agreement for a 15% subsample of cases. Of all cases, 330 (48%) were identified as having had pre–9-1-1 delay. Delay was less commonly associated with witnessed arrest (odds ratio [OR] 2.7; 95% confidence interval [CI] 2.0–3.7%) andpublic location (OR 1.57; 95% CI 1.1–2.2%). In a multivariate model, only initial-rhythm ventricular tachycardia/ventricular fibrillation was associated with improved survival (OR 2.28; 95% CI 1.3–4.1), andpre–9-1-1 delay was associated with decreased survival (OR 0.46; 95% CI 0.3–0.9%). Conclusion. This method demonstrated that prehospital delay is common in OHCA andis associated with increased mortality. Measurement of pre–9-1-1 delay may improve precision of predictive models for OHCA survival.

Key words:

• heart arrest
• outcome
• bystander effects
• delay