Timing is survival: modeling how earlier calls improve cardiac arrest outcomes

TL;DR

Earlier emergency calls significantly improve survival after cardiac arrest, especially in rural areas with longer ambulance response times.

Contribution

The study quantifies survival gains from earlier emergency calls using a survival decay function across diverse Norwegian municipalities.

Findings

Earlier calls by 5 minutes increased survival in Bergen from 47.7% to 68.6%.

Even 1–2 minute improvements in call timing provided meaningful survival benefits.

Rural areas like Lurøy showed potential for significant survival gains with earlier calls.

Abstract

Survival after out-of-hospital cardiac arrest decreases by 5%–12% for every minute of delay in treatment. Ambulance response times vary widely across Norway, particularly between urban and rural municipalities. Advances in digital health technologies may encourage earlier patient contact with emergency services, potentially mitigating these delays.

We analyzed official response time data from four Norwegian municipalities representing diverse geographic contexts (Bergen, Tokke, Lurøy, Sørfold). Using a survival decay function (Equation), we simulated changes in survival probability under scenarios where emergency calls were placed 1, 5, or 10 min earlier than observed.

Baseline survival probabilities varied substantially across municipalities, from 47.7% in Bergen (mean response 10.2 min) to 9.3% in Lurøy (32.8 min). Simulated earlier calls produced marked gains: in Bergen, survival increased from 47.7% to 68.6% with a five-minute advance; in Sørfold, from 19.4% to 27.9%; and in Tokke, from 29.9% to 43.1%. Even modest improvements (1–2 min) yielded meaningful survival benefits.

Geographic disparities in emergency response times strongly influence survival after cardiac arrest. Wearables and AI-based monitoring cannot predict cardiac arrest but may promote earlier recognition of abnormal physiological states and timelier emergency calls. If widely adopted, such technologies could provide substantial survival gains, particularly in rural and remote regions.

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