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Prehospital Evidence-Based Guidelines. Daniel Spaite, MD Professor of Emergency Medicine The University of Arizona. History and Development of EBM. Historical assumption: Medical education, CME, experience, and interaction with colleagues are adequate to lead to good clinical decisions.

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Prehospital Evidence-Based Guidelines

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prehospital evidence based guidelines

Prehospital Evidence-Based Guidelines

Daniel Spaite, MD

Professor of Emergency Medicine

The University of Arizona

history and development of ebm
History and Development of EBM

Historical assumption:

Medical education, CME, experience, and interaction with colleagues are adequate to lead to good clinical decisions

early 1970 s three findings destroyed the assumption
Early 1970’s: Three findings destroyed the assumption

1. Documentation of wide variation in practice patterns (Wennberg, 1973)

Dramatic procedural variation (RAND)

2. Most medical practice was founded on tradition/experience rather than evidence.

Cochrane-1972: Many standards of care were found to be ineffective, or even dangerous.

IOM Report-1985: Estimate: Only 15% of medical practices based upon solid evidence.

early 1970 s three findings destroyed the assumption1
Early 1970’s: Three findings destroyed the assumption

3. Enormous lag-time from new research findings to practice.

Dutton-1988: “Worse than the Disease: Pitfalls of Medical Progress.”

the ever widening gap
The ever widening gap

> 100 new articles related to EM/day (Medline)

Scientific knowledge



Practice of Medicine



terminology a decade into the movement
TERMINOLOGY: A decade into the “movement”

“Evidence-Based Guidelines”

1990 (Eddy: JAMA:263; 1265)

“Evidence-Based Medicine:

1991 (Guyatt: ACP Journal Club, No. 2: A-16).

translating new knowledge to patient care
Translating New Knowledge to Patient Care

Eddy’s categorization for EBM:

Evidence-Based Individual Decision-making (EBID)

Brings current knowledge to the bedside in real-time.

DIRECT use of evidence to impact the care of an INDIVIDUAL patient.

Evidence-Based Guidelines (EBG)

Policies and standards that help guide clinical decision-making based upon bring state-of-the-art knowledge.

INDIRECT use of evidence to change policy, practice patterns, regulations, insurance coverage, etc.

ebid and ebg

BOTH are conceptually based upon a hierarchy of evidence quality

University of Arizona EM: EBID 


Will this EVER be used in prehospital care???

Currently not feasible: Technical/time constraints

Physician surrogates: Medical decision-making???

ebg around a long time
EBG: Around a Long Time

Traditional methods:

“Global subjective judgment”




Traditional methods often wrong:

1916: “Once a C-section…always a C-section”

ebg the age of evidence based methods
EBG: The Age of “Evidence-Based” Methods

During the 80’s, huge advances:

By the late 90’s:

“…it is widely accepted that guidelines should be based on evidence and the only acceptable use of consensus-based methods is when there is insufficient evidence to support an evidence-based approach.” (Eddy)

What’s it gonna take in EMS???

the magnitude of the challenge

An overview of the road that’s ahead of us

necessary steps for truly evidence based guidelines
Necessary Steps for TRULY “Evidence-Based” Guidelines

STEP #1: Critical evaluation of the literature

EVERY potential clinical condition:

Comprehensive, systematic literature review.

UNC Evidence-based Practice Center (EPC): (Lohr: Intl J Qual Health Care: 2004;16:9-18)

121 different approaches for rating individual study quality.

Only 19 met standards for proper assessments

necessary steps
Necessary Steps

STEP #2: Critical evaluation of the CUMMULATIVE evidence

Must evaluate the quality of the BODY of evidence

This is more difficult than rating a single investigation.

Assess the consistency and heterogeneity of study designs

Assess the comparability of the Risk Adjustment among the studies

Weight each study

Study size, methodology, quality

UNC-EPC: (Lohr: 2004)

40 methods for rating the strength of a body of evidence.

8 met standards for proper assessments

necessary steps1
Necessary Steps

STEP #3: Critical evaluation of the CHAINS of evidence

RARE to find a body of knowledge that “writes the guideline for you.”

Requires explicit cognitive steps that translates DIRECT evidence into guideline through INFERENCES.

Example: Animal studies  Human studies  Guideline applied across a broad population in potentially dramatically different settings.

Inevitably requires judgment, inference, and opinion

necessary steps2
Necessary Steps

STEP #4: Critical evaluation of the PREHOSPITAL implications of the body of evidence

Strong evidence for EFFICACY of an intervention does not mean that it will be EFFECTIVE in the field.

Lack of prehospital studies must be taken into account even with strong positive evidence in other settings.

“Medicine-Based Evidence: A Prerequisite for Evidence-based Medicine.” (Knottnerus: BMJ;315:1997)


necessary steps3
Necessary Steps

STEP #5: Critical evaluation of other pertinent issues

Systems-related factors. Effectiveness may vary with:

Rural vs. urban settings


e.g. Is a separate pediatric guideline needed?

Operations: (e.g. response/transport intervals)

Patient populations

e.g. Cost-effectiveness varies with prevalence

Socioeconomics: At-risk populations

Impact of delaying an intervention: Does it have to be done?

Extremes are easy: Cardiac arrest; Tinea pedis

Urgent…but not emergent interventions

necessary steps4
Necessary Steps

STEP #5 (Continued): Critical evaluation of other pertinent issues

Risk for harm


Feasibility and practicality

Value-judgments: Individual, religious, cultural variation

Example: Life vs. profound morbidity

Confidence of benefit vs. magnitude of benefit

Confidence of benefit vs. significance of benefit

Related specialty-based guidelines if they exist (AHA: CPR/ACLS)

Evaluation of current guidelines/protocols

This alone is an enormous undertaking

necessary steps5
Necessary Steps

STEP #6: Evaluation of whether a guideline is appropriate at all

What if all evidence is WEAK?

When should a stand be taken that clearly states that insufficient evidence exists…and that a guideline is inappropriate?

What if there are already LOTS of guidelines out there?

Are there commonly used interventions that should be “trashed” and NOT recommended for use in EMS?

If CONSENSUS is the basis for a guideline, how is this distinguishable from EVIDENCE-based guidelines?

What are the implications of having these guidelines LOOK equally authoritative when they make it to the street?

necessary steps6
Necessary Steps

STEP #7: Plan for recurrent, future evaluations of evidence and revisions of the guidelines

If there’s a lack of commitment to future changes based upon new evidence…is it best not to start in the first place?

Guidelines are NOT harmless!!!

Guidelines hang around a LONG time!!!


Diethylstilbestrol (DES)

1938 – 1971: Recommended by expert consensus guideline to prevent miscarriage

4.8 million pregnant women received it

1971 FDA halted it’s use: No statistical benefit but significant harm (vaginal cancer, breast cancer, etc.)

huge questions

Are we SURE we mean EVIDENCE-based guidelines…OR…do we REALLY mean CONSENSUS-based guidelines???

Will protocols be developed and supported where the only “evidence” is opinion and theory?

steering committee s consensus
Steering Committee’s “Consensus”

A high “threshold” for requiring solid evidence for a guideline to be recommended.

When in doubt, err on the side of requiring strong evidence before propagating guidelines.

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