What Makes a Protocol "Evidence-Based"?
Evidence-based protocols are clinical guidelines grounded in the best available scientific research, combined with clinical expertise and patient values. In EMS, protocols dictate the assessment and treatment algorithms you follow for each patient presentation. Understanding how these protocols are developed helps you appreciate why they exist and why they change over time.
The Evidence Hierarchy
Not all evidence is created equal. The evidence hierarchy, from strongest to weakest, includes:
- Systematic reviews and meta-analyses: Comprehensive analysis of multiple studies on the same topic
- Randomized controlled trials (RCTs): Experiments with random assignment to treatment and control groups
- Cohort and case-control studies: Observational studies that follow groups over time or compare cases to controls
- Case series and case reports: Descriptions of individual or small groups of patients
- Expert opinion: Recommendations based on clinical experience without systematic research
Ideally, every EMS protocol would be based on high-quality RCTs conducted in the prehospital setting. In reality, prehospital research is challenging due to informed consent issues, variable patient populations, and the difficulty of controlling conditions in the field. Many EMS protocols are therefore based on a combination of hospital-based research, observational data, and expert consensus.
How Protocols Change
Protocols evolve as new evidence emerges. For example, the recommendation for spinal immobilization changed dramatically over the past decade as research showed that rigid backboards cause harm without improving outcomes. Similarly, the guidelines for tourniquet use shifted from "last resort" to "early application" based on evidence from military medicine. The American Heart Association updates CPR guidelines every five years based on a comprehensive review of the cardiology literature.
Staying Current
As an EMS provider, you are responsible for knowing your current local protocols. Attend protocol update meetings, read your medical director's communications, and review new guidelines when they are released. Follow organizations like NAEMSP, NASEMSO, and the AHA for updates to national standards. Understanding the evidence behind your protocols makes you a better clinician and helps you adapt when real-world situations do not fit neatly into protocol algorithms.