ESO EMS Index: one in five patients accounts for 44% of 911 calls
ESO Solutions has published its ninth annual EMS Index, a benchmark report built on de-identified prehospital data from more than 17.3 million emergency encounters across the United States in calendar year 2025. The headline finding is stark: 19% of the 8.8 million unique patients tracked through ESO's Longitudinal Patient Record called 911 more than once last year, collectively accounting for 44% of all responses.
The most common dispatch complaints among repeat callers — sick person, falls, breathing difficulties, chest pain, and convulsions — point overwhelmingly to chronic conditions rather than acute emergencies. ESO argues that longitudinal tracking of these individuals is the prerequisite for community-level interventions such as community paramedicine or chronic disease management pathways that could redirect demand away from ambulance dispatch.
"When numbers like these come out, the temptation is to infer the system is being misused," said Dr Brent Myers, chief medical officer at ESO. "For many of these patients, calling 911 is the most accessible option for receiving care, as our health care system doesn't always provide readily available alternatives."
Obstetric care gap
The 2026 Index highlights a persistent treatment shortfall for obstetric emergencies. In April 2025, the American College of Obstetricians and Gynecologists released updated model EMS guidelines calling for prehospital treatment of severe hypertension in pregnancy based on blood pressure readings alone, irrespective of symptoms. Data from 2025 responses show that treatment rates for severe hypertension in pregnancy remain at approximately 5%, while postpartum haemorrhage treatment stands at 17% — both figures broadly unchanged from the prior year.
Dr Myers acknowledged that protocol and formulary changes take time to filter through EMS agencies, but noted that the main barrier is not magnesium sulphate — already carried on most units — but antihypertensives and oxytocin, which the updated ACOG guidelines now require. The Index is designed to give individual agencies the data to track their own progress in closing that gap.
Dispatch recognition and broader trends
A new measure introduced in this edition examines how early stroke identification at the point of the 911 call affects outcomes. When dispatchers correctly flagged a call as a potential stroke, EMS clinicians completed the full stroke bundle 72% of the time; when the call came in under a different category — fall, headache, or general weakness — bundle completion dropped to 47%. The 25-percentage-point gap illustrates how the initial dispatch impression cascades through facility selection and clinical response.
On the drug misuse front, the Index recorded a third consecutive year of decline in opioid-related encounters as a proportion of all 911 responses, mirroring national CDC trend data. At the same time, documented prehospital administrations of buprenorphine more than doubled between 2023 and 2025, reflecting the expansion of field-initiated treatment programmes that allow paramedics to begin medication-assisted treatment at the scene.
The report sits alongside ESO's annual Fire Service Index and Trauma Index, and the company positions the suite as a quality-improvement tool rather than a scientific study; all measures are descriptive and observational, and the data does not establish causation.
Market context and sector read-across
The findings carry implications beyond EMS operations. Payers, health systems, and local government commissioners are increasingly focused on reducing avoidable emergency utilisation, and data assets that identify frequent 911 callers are becoming central to value-based care contracting. A growing number of digital-health and population-health management companies are competing in the community paramedicine software space, and ESO's report arguably strengthens the business case for investment in that category.
Regulatory interest in prehospital data standards is also rising. The National Emergency Medical Services Quality Alliance (NEMSQA), whose Syncope-01 quality measure features in this year's Index, is one of several bodies working to align prehospital metrics with broader healthcare quality frameworks — a trend that favours data-platform providers with longitudinal patient record capabilities like ESO's.