How Many Time-Critical Emergencies? A Population-Based National Estimate of Attended Events per 100,000 US Residents

Objectives. To estimate how many time-critical emergencies fire and emergency medical services (EMS) crews attend each year per 100,000 US residents. We counted events in which a crew reached a living patient or a trapped person whose outcome plausibly depends on how soon effective treatment starts. Methods. For 30 medical conditions, we took annual counts from US registries and datasets, or multiplied a national incidence count by the share of patients EMS attended. A condition was Tier A when a published study linked a measured delay, from minutes to a few hours, to death or major disability. Conditions whose time sensitivity rests on guidelines or expert consensus were Tier B. Fire and rescue events came from twelve months of National Emergency Response Information System public data, scaled to national totals. We removed double counting between conditions. Results. Crews attended an estimated 589 time-critical events per 100,000 residents a year (494 to 697 with every condition at its low or high value), equal to 4.3% of 9-1-1 EMS activations. Medical conditions accounted for 583 after removing overlap. Of these, 350 were Tier A, led by ischemic stroke (120.2) and EMS-treated cardiac arrest (78.7). Opioid overdose (123.4) led the 233 Tier B events. Those three conditions made up 55% of the medical total. Fire and rescue events added 6. Conclusions. At national rates, a US community of 100,000 can expect its fire and EMS crews to attend about 589 events a year in which time to treatment may change the outcome. That is roughly 11 a week, nearly all of them medical. The count measures how often response time can matter in the events crews attend, and it gives a denominator for valuing a faster response.