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What Should You Know About Evidence-Based Guidelines?

As healthcare professionals we want to provide patients the best possible medical care. Prehospital care, like the rest of medicine, is constantly changing, since the research performed today will shape the medical care we deliver tomorrow.1–4 

The strongest type of research study is a randomized controlled trial (RCT). An RCT minimizes potential bias by randomizing the administration of an intervention to some subjects while others (the control group) don’t get it. Ideally evidence-based guidelines (EBGs) in EMS should be based on multiple RCTs. To properly develop EBGs, a multistep process (the GRADE methodology) is required to review research studies on a specific topic. 

In 2015 the National Association of EMS Physicians (NAEMSP), along with 57 EMS stakeholder organizations, began the Prehospital Guidelines Consortium (PGC). The PGC has a mission to assist in the development, implementation, and evaluation of prehospital evidence-based guidelines. Future objectives for the PGC include promoting development of future EMS EBGs, promoting grant funding for EMS EBGs, development of research related to EMS EBGs, promoting implementation of EMS EBGs, developing education related to new EBGs, and promoting standardized evaluation methods for EMS EBGs.

An Introduction to Evidence-Based Medicine

Evidence-based medicine (EBM) or evidence-based practice (EBP) is the thoughtful integration of the best available research findings with consideration for clinical expertise and judgment, while also taking into account the values and preferences of patients and clinicians. To clarify, EBM is not based solely on personal experience, anecdote, or “how we’ve always done it,” but applies a scientific method to support (or sometimes refute) these beliefs.3,5 

The goals of EBM include improvement in the quality of medical care, improvement in patients’ clinical outcomes, maintaining clinician/patient satisfaction, and ensuring consistency of care between clinicians and across healthcare systems.6–8 Four examples of EBM include the AHA guidelines for resuscitation, spinal motion restriction guidelines, CDC guidelines for field triage, and evidence-based guideline for pediatric prehospital seizure management using GRADE methodology.9–12 

Many national EMS organizations now support incorporating EBM into EMS guidelines and protocols. In 2012 the National EMS Advisory Council recommended it.13 In 2013 the Federal Interagency Committee on EMS published a strategic plan that included support for the development, implementation, and evaluation of evidence-based guidelines.5 

In 2017 research and evidence-based medicine became part of the updated National Registry’s Core Competency Program (CCP) learning goals. The CCP update implies that every nationally registered EMS provider certified at the EMT level or above will receive refresher content on EBM.14

Different Types of Research 

There are many types of research, including case reports, case series, case control studies, cohort studies, and randomized controlled trials (see Table 1). A case report or case study is something you did that seemed to work (or not work) the one time you tried it, so you decided to continue doing it (or not doing it) based on that one case. A case series is something you did several times that seemed to work (or not work), so you decided to continue doing it (or not doing it) based on those several cases. In contrast, case control studies use an outcome or intervention and compare study groups to control (standardized nonstudy) groups. 

A cohort study retrospectively or prospectively follows a group of individuals to determine the incidence of a particular outcome. Unlike a cohort study, where the intervention is not controlled by the investigator, in a randomized controlled trial the intervention is controlled by the investigator. 

The strongest type of research study is an RCT. Unfortunately, sometimes an RCT cannot be performed because it is not possible or practical to randomize the intervention. In addition, RCTs are often very costly, time consuming, require statistical analysis, and need large numbers of patients. Furthermore, an RCT may not be even feasible due to the setting.15 In order to prevent any local geographic bias, the best RCTs are multicenter trials held at several sites. 

One quickly realizes that EMS EBGs should ideally be based on multiple RCTs, not just one. Developing an EBG is easy when several RCTs all agree that an intervention provides a benefit (or no benefit). Unfortunately there are times where RCTs directly contradict each other. There are some RCTs that support the prehospital care delivered to patients, but more commonly there are none, and EMS guidelines are often based on weak research or, even worse, simply expert consensus. 

EBGs and GRADE Methodology

To properly develop an EBG, a multistep process (the GRADE methodology, for grading of recommendations assessment, development, and evaluation) is required to review several research studies on a specific topic (see Figure 1).16 This process begins by identifying an expert multidisciplinary panel that develops a focused question using what is called a PICO framework (patient/population, intervention/indicator, compare/control, outcome, plus time/type of study or question). This process requires close collaboration of the entire panel.

The panel then develops and selects specific patient outcomes important for decision-making. Outcomes determined to be critical and important are evaluated using a systematic review process. Outcomes rated as not important need not be considered any further. The novelty of the GRADE approach is that the outcomes are evaluated across rather than within studies. In other words, a different body of evidence may contribute information to different outcomes being considered. 

When an evaluation of the outcomes across studies has taken place, evidence profiles using software such as GRADEpro are developed.17 The presentation of this information can take place either in typical evidence profiles or in a summary-of-findings table, where a detailed assessment of the underlying confidence in an estimate of effect by outcome is then combined with an actual analysis. 

An expert panel reviews the evidence and will then “grade” its quality. This is done for each outcome across four categories: high, moderate, low, or very low, on the basis of eight factors that either increase or decrease the initial quality (see the upper right-hand corner of Figure 1). Randomization is considered the best method to protect against bias, and the evidence from RCTs usually is considered as higher quality. There are five factors that can lower the quality (grade) of evidence, and three that increase it (Figure 1). 

Once all critical outcomes for decision-making have been evaluated, an overall confidence in the estimate of effect to support a recommendation or an overall GRADE of the quality of evidence is assigned. The overall GRADE is based on the outcome with the lowest quality of evidence, given that it is a critical outcome. This information is provided back to the panel. 

The guideline panel needs to formulate a recommendation by considering four factors: the quality of evidence, the balance between benefits and downsides, values and preferences, and resources used. The panel will then formulate recommendations in a clear and unambiguous way using standardized wording, such as using the term recommend for strong recommendations and the term suggest for conditional or weak recommendations. Other terminology sometimes used includes should and may. Guideline panels will express GRADE’s two directions of the recommendation either for or against an intervention or diagnostic test or strategy and the strength of this recommendation by determining that it is either a strong or a conditional recommendation. Other users of GRADE may use the evidence summarized according to the GRADE approach for health policy decisions. 

Prehospital Guidelines Consortium

In 2007 the Institute of Medicine’s Committee on the Future of Emergency Care recommended that a multidisciplinary panel establish a model for developing evidence-based protocols for prehospital care.13 In 2015 NAEMSP, along with 57 EMS stakeholder organizations, began the Prehospital Guidelines Consortium (PGC).18 

The PGC has a mission to assist in the development, implementation, and evaluation of prehospital EBGs. The PGC also identified a need for better education of the EMS community in regards to EBM. In an effort to help EMS instructors, the PGC Education Committee developed an educational PowerPoint entitled “Research and Evidence-Based Guidelines in EMS.” EMS educators/instructors/professionals can download this slideshow presentation from the PGC website free of charge.

Another helpful resource is the Dalhousie University website Prehospital Evidence Based Practice. This site incorporates research studies on many different topics, but unfortunately its reviewers do not use GRADE methodology.2


The ultimate goal of EMS is provide patients the best healthcare possible. Yet research is constantly changing and improving how prehospital medical care is delivered. For this reason, EBM and EBGs using GRADE methodology are a crucial component of EMS now and in the future. The PGC has a mission to assist in the development, implementation, and evaluation of prehospital evidence-based guidelines. 


1. Bledsoe BE. Searching for the evidence behind EMS. Emerg Med Serv, 2003; 32(1): 63–7.

2. Carter AJE, Jensen JL, Petrie DA, et al. State of the evidence for emergency medical services (EMS) care: The evolution and current methodology of the Prehospital Evidence-Based Practice (PEP) program. Healthcare Policy, 2018; 14(1): 57–70.

3. Treasure T. From anecdote to EBM. J R Soc Med, 2006; 99(5): 267–70.

4. Institute of Medicine. Evidence-Based Medicine and the Changing Nature of Healthcare: 2007 IOM Annual Meeting Summary. Washington, D.C.: National Academies Press, 2008.

5. Brown KM, Macias CG, Dayan PS, et al. The Development of Evidence-based Prehospital Guidelines Using a GRADE-based Methodology. Prehosp Emerg Care, 2014; 18(sup1): 3–14. 5. 

6. Adelgais KM, Sholl JM, Alter R, Gurley KL, Broadwater-Hollifield C, Taillac P. Challenges in Statewide Implementation of a Prehospital Evidence-Based Guideline: An Assessment of Barriers and Enablers in Five States. Prehosp Emerg Care, 2019 Mar–Apr; 23(2): 167–78.

7. Martin-Gill C, Gaither JB, Bigham BL, Myers JB, Kupas DF, Spaite DW. National Prehospital Evidence-Based Guidelines Strategy: A Summary for EMS Stakeholders. Prehosp Emerg Care, 2016; 20(2): 175–83.

8. Gausche-Hill M, Brown KM, Oliver ZJ, et al. An Evidence-based Guideline for Prehospital Analgesia in Trauma. Prehosp Emerg Care, 2014; 18 Suppl 1: 25–34.

9. Sasser SM, Hunt RC, Faul M, et al. Guidelines for field triage of injured patients: recommendations of the National Expert Panel on Field Triage, 2011. MMWR, 2012; 61(RR-1): 1–20.

10. Shah MI, MacIas CG, Dayan PS, et al. An evidence-based guideline for pediatric prehospital seizure management using grade methodology. Prehosp Emerg Care, 2014; 18 Suppl 1: 15–24. 

11. Fischer PE, Perina DG, Delbridge TR, et al. Spinal Motion Restriction in the Trauma Patient–A Joint Position Statement. Prehosp Emerg Care, 2018; 22(6): 659–61.

12. Kleinman ME, Perkins GD, Bhanji F, et al. ILCOR Scientific Knowledge Gaps and Clinical Research Priorities for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care: A Consensus Statement. Resuscitation, 2018; 127: 132–46.

13. Lang ES, Spaite DW, Oliver ZJ, et al. A national model for developing, implementing, and evaluating evidence-based guidelines for prehospital care. Acad Emerg Med, 2012; 19(2): 201–9.

14. National Registry of Emergency Medical Technicians. National Continued Compentency Program,

15. West SG, Duan N, Pequegnat W, et al. Alternatives to the randomized controlled trial. Am J Public Health, 2008; 98(8): 1,359–66.

16. Schunemann H, Ahmed F, Mergan R. Guideline Development Using GRADE (Online). Department of Clinical Epidemiology and Biostatistics, McMaster University.

17. Patterson PD, Higgins JS, Weiss PM, Lang E, Martin-Gill C. Systematic Review Methodology for the Fatigue in Emergency Medical Services Project. Prehosp Emerg Care, 2018; 22 Suppl 1: 9–16.

18. Prehospital Guidelines Consortium,

19. Prehospital Guidelines Consortium. Research and Evidence-Based Guidelines in EMS,

Juan A. March, MD, FAEMS, FACEP, is chief for the Division of EMS and a professor with the Department of Emergency Medicine at East Carolina University. He serves on the board of directors for CAPCE and as chair of the Education Committee for the Prehospital Guidelines Consortium.  

Joan Somes, PhD, RN-BC, CEN, CPEN, FAEN, REMT-P, recently retired after 40 years as bedside emergency department nurse and staff educator and is now working part-time as a critical care educator for Regions Hospital EMS in Oakdale, Minn., and is section editor for the Journal of Emergency Nursing’s geriatric column.

Christian Martin-Gill, MD, MPH, is chief of the Division of EMS and EMS fellowship program director at the University of Pittsburgh Medical Center. He serves as chair of the Prehospital Guidelines Consortium.

Mike McEvoy, PhD, NRP, RN, CCRN, is the EMS coordinator for Saratoga County, N.Y., and the professional development coordinator for Clifton Park Halfmoon EMS. He is the chair of the EMS Section board of directors for the International Association of Fire Chiefs and chief medical officer and a firefighter/paramedic for the West Crescent Fire Department. 

Joann Freel, BS, has worked in the medical education field for more than 34 years and is currently on the board of directors for the National EMS Museum. She recently retired as chief executive officer for the National Association of EMS Educators (NAEMSE).

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