Prehospital Evidence-Based Prehospital Evidence-Based GuidelinesGuidelines

Daniel Spaite, MDProfessor of Emergency Medicine

The University of Arizona

History and Development of EBMHistory and Development of EBM

Historical assumption:– Medical education, CME, experience, and

interaction with colleagues are adequate to lead to good clinical decisions

Early 1970Early 1970’’s: Three findings s: Three findings destroyed the assumptiondestroyed 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 1970Early 1970’’s: Three findings s: Three findings destroyed the assumptiondestroyed 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 gapThe ever widening gap

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

knowledge

(bench)

Practice of Medicine

(bedside)

1925

2008

TERMINOLOGY: A decade into the TERMINOLOGY: A decade into the ““movementmovement””

“Evidence-Based Guidelines” – 1990 (Eddy: JAMA:263; 1265)

“Evidence-Based Medicine: – 1991 (Guyatt: ACP Journal Club, No. 2: A-16).

Translating New Knowledge to Translating New Knowledge to Patient CarePatient 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 EBGEBID and EBG

BOTH are conceptually based upon a hierarchy of evidence quality

University of Arizona EM: EBID

General Grades of EvidenceGeneral Grades of Evidence

A = B =

C =

D =

EBID

Will this EVER be used in prehospital care???– Currently not feasible: Technical/time

constraints– Physician surrogates: Medical decision-

making???

EBG: Around a Long TimeEBG: Around a Long Time

Traditional methods: – “Global subjective judgment”– “Preference-based”– “Consensus-based”– “Opinion-based”

Traditional methods often wrong: – 1916: “Once a C-section…always a C-section”

EBG: The Age of EBG: The Age of ““Evidence-BasedEvidence-Based”” MethodsMethods

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 THE MAGNITUDE OF THE CHALLENGECHALLENGE

An overview of the road that’s ahead of us

Necessary Steps for TRULY Necessary Steps for TRULY ““Evidence-BasedEvidence-Based”” Guidelines 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 StepsNecessary 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 StepsNecessary 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 StepsNecessary 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)

The “Real World” EFFICACY vs. EFFECTIVENESS

Necessary StepsNecessary Steps

STEP #5: Critical evaluation of other pertinent issues – Systems-related factors. Effectiveness may vary with:

» Rural vs. urban settings» Demography:

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 StepsNecessary Steps

STEP #5 (Continued): Critical evaluation of other pertinent issues – Risk for harm – Cost– 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 StepsNecessary 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 StepsNecessary 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!!!

– Example: » 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 QUESTIONSHUGE 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 CommitteeSteering Committee’’s s ““ConsensusConsensus””

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. The HOT topic