discussion 6
Chapter 14: Evidence Based Medicine and Clinical Practice Guidelines
Robert Hoyt MD
William Hersh MD
After reviewing the presentation, viewers should be able to:
State the definition and origin of evidence based medicine
Define the benefits and limitations of evidence based medicine
Describe the evidence pyramid and levels of evidence
State the process of using evidence based medicine to answer a medical question
Recall important online and smartphone evidence based medicine resources
Describe the interrelationship between clinical practice guidelines, evidence based medicine, and electronic health records
Define the processes required to create and implement a clinical practice guideline
Learning Objectives
Information technology has the potential to improve decision making through online medical resources, electronic clinical practice guidelines, electronic health records (EHRs) with decision support, online literature searches, digital statistical analysis and online continuing medical education
Healthcare reform is dependent on quality healthcare and that is dependent on the best evidence available
Introduction
Revised 2000: is a systematic approach to clinical problem solving which allows the integration of the best available research evidence with clinical expertise and patient values
EBM Definition
Why EBM is important from the viewpoint of the National Academy of Medicine: “Patients should receive care based on the best available scientific knowledge. Care should not vary illogically from clinician to clinician or from place to place”
We are moving slowly from anecdotal evidence to randomized controlled trials
Importance of EBM
Current methods of keeping medically or educationally up-to-date do not work
Translation of research into practice is often very slow
Lack of time and the volume of published material results in “information overload”
The pharmaceutical industry bombards clinicians and patients every day; often with misleading or biased information
Much of what is considered the “standard of care” in every day practice has yet to be challenged and could be wrong
Importance of EBM
Continuing Medical Education (CME): we know this is often ineffective
Clinical Practice Guidelines (CPGs): will be covered later but CPGs may not produce change
Expert advice: much better than no information but not always evidence based
Reading: “like drinking water from a fire hose”. Need focus so the best and most pertinent content is read
Traditional Methods for Gaining Medical Knowledge
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A clinical question is generated. Use PICO tools *
Seek the best evidence using an EBM resource
Critically appraise the evidence using tools we will cover later in the presentation
Apply the evidence to the patient, taking into account their values, preferences and circumstances
Example: For patients over age 65 with a suspected stroke or TIA, which is the preferred initial imaging technique (MRI or CT or both)?
The EBM Process to Answering a Clinical Question
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* P for patient or problem. Define the patient or group; I for intervention or therapy of interest; C for comparison with other drug or placebo?; O for outcome of interest, mortality? Some add T for type of study = PICOT. We will focus on therapy questions
Validity:
Internal: Is the study believable? Look for apparent biases or errors in selecting patients, measuring outcomes, conducting the study, or analyzing the results
External: are the results generalizable to your population of interest? If you have a geriatric population results on teenagers might be irrelevant
Results:
Results should be assessed in terms of the magnitude of treatment effect and precision which we will comment on later
Terminology Used in Answering Clinical Questions
Therapy Question: does the addition of Plavix to aspirin reduce the incidence of future strokes?
Prognosis Question: will lowering the average blood pressure to less than 120/80 reduce the likelihood of a stroke?
Diagnosis Question: which is more sensitive and specific for detecting a heart attack, CPK or troponin?
Harm Question: how many patients will have renal insufficiency due to an ace inhibitor compared to a beta blocker?
Cost question: which is more cost effective to reduce hospital readmissions for heart failure, inpatient case management or home health nursing care?
Most Common Types of Clinical Questions
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Evidence Pyramid
Better evidence
But fewer published
articles
Case reports/case series: collections of reports on treatment of patients without control groups; much less scientific significance
Case control studies: study patients with a specific condition compared with people who do not the condition; less reliable than randomized controlled trials
Cohort studies: evaluate and follow patients who have a specific exposure or receive a particular treatment over time and compare them with another group that is similar but has not been affected by the exposure being studied; the two groups may differ in ways other than the variable under study
Randomized controlled trials (RCTs): subjects are randomly assigned to a treatment or a control group that received placebo or no treatment; only difference between the two groups is the intervention being studied.
“Double blinded” – both the investigators and the subjects do not know whether they received an active medication or a placebo
RCTs are the gold standard design to test therapeutic interventions
Evidence Pyramid Studies
Systematic reviews: answer a focused question by including multiple RCTs. Several reviewers scan the medical literature with specific criteria
Meta-analyses: quantitative summary of systematic reviews using statistical techniques to combine the results of several studies, thereby leading to larger numbers (more statistical significance) and a wider range of patients
Evidence Pyramid Studies
GRADE: Grading of Recommendations, Assessment, Development and Evaluation is a common framework, but many others exist
Level 1: High quality evidence derived from consistent RCTs
Level 2: Moderate quality evidence inconsistent or less methodologically strong RCTs; or exceptionally strong observational evidence
Level 3: Low quality evidence, usually from observational studies
Level 4: Very low quality evidence from flawed observational studies, indirect evidence or expert opinion
Levels of Evidence
A study can be statistically but not medically significant. There are tools that shed more practical light on the results, such as NNT
The risk for people who are in the experimental group is called the experimental event rate (EER); whereas the risk for people who are in the control group is called the control event risk (CER)
The relative risk is the EER/CER or a ratio
The relative risk reduction (RRR) is the EER-CER/CER
The absolute risk reduction (ARR) is the EER-CER
Number Needed to Treat (NNT)
The NNT is calculated by dividing 1 by the ARR (or 100/ARR if the ARR is expressed as a percentage and not a fraction
NNT calculates the number of patients who need to be treated with X to prevent one Y, over a specific time
An example: drug A is associated with stroke in 5% of patients, compared to 7% of patients on placebo over a one year trial
RRR = 5%-7%/7% = 29%; ARR = 7%-5% = 2% (ignore minus signs)
NNT = 100/2% or 50 patients need to be treated for one year to prevent one stroke
Number needed to harm (NNH) is calculated by harm percentage divided into 100
Web site http://www.thennt.com/ devoted to NNT and EBM
Number Needed to Treat (NNT)
Low yield of excellent quality articles in general
Many repeated studies show different results
Results are very frequently inconclusive
Many studies are poorly designed, have inadequate number of patients, and have some bias
Many medical journals are now requiring registration of all clinical trials in public registries
Limitations of the Medical Literature
Different rating systems for evidence
Different conclusions drawn by different people
Reviews are very time intensive so reviews don’t exist for every medical condition
Some view EBM as “cook book medicine”
RCTs are expensive, so often sponsored by drug companies, introducing bias
Limitations of EBM
Health informatics studies are under the microscope:
Often small, non-randomized, non-controlled studies
Frequently based on before and after implementation studies
Technology studies are hard to double blind
Early studies failed to look at unintended consequences of technology; they only looked for benefit
Excellent cost analyses are frequently missing
Much more on this in the textbook
Evidence Based Health Informatics (EBHI)
EBM Resources
JAMA Evidence
Clinical Evidence
Cochrane Library
Cochrane Summaries
Evidence Updates
ACP Journal Club
Practical Pointers for Primary Care
Essential Evidence Plus
TripDatabase
OVID
SUMSearch
Bandolier
Centre for EBM
Best Bets
Evidence Based Health Care
Google (insert “evidence based”)
NNT web site
MDCalc has EBM calculator tools
EBM for mobile technology: MedCalc3000 calculators are web based and exist for mobile platforms
More EBM Resources
The Institute of Medicine in 1990 defined clinical practice guidelines (CPGs) as: “systematically developed statements to assist practitioner and patient decisions about health care for specific clinical circumstances”
CPGs are based on EBM and are generally embraced by most specialties around the world
While they are embraced they are not always utilized by physicians for a variety of reasons
Clinical Practice Guidelines
Panel of subject matter experts convene to evaluate an important medical problem (high cost, high risk, etc.), usually with a disease management team, possibly IT, epidemiology, etc.
Team reviews local issue and evidence and examines national evidence; balancing costs, benefits and risks
Team evaluates the applicability of the guideline to the local scenario
Leadership at the top and the medical and nursing staff are critical for acceptance in a healthcare system
Implementation details are important as well; will it be paper or electronic based? Part of EHR?
Clinical Practice Guidelines Steps
Practice setting: are the clinicians too busy or indifferent to new evidence?
Contrary opinion: do the experts agree?
Sparse data: is the evidence conclusive?
Expect low initial acceptance
CPGS can be too long, without a summary
Lack of local champions
CPGs may lack patient input with both the writing of the CPGs and the implementation
Incentives to adopt may be missing for clinicians
Barriers to CPGs
CPG Example Hypertension CPG by Kaiser
CPGs available for mobile technology
Web based CPGs (risk calculators)
ATP III
FRAX
Gail breast cancer risk assessment
Stroke risk calculator
EHR-based CPGs:
Library of CPGs embedded in the EHR
Order sets for new admissions
Electronic CPGs
National Guideline Clearinghouse
National Institute for Health and Clinical Excellence
Agency for Health Care Research and Quality
Health Team Works
Institute of Clinical Systems Improvement
CPG Resources
EBM is the pursuit of the best available evidence
EBM is based on a hierarchy or pyramid of evidence
There are multiple limitations of the medical literature and EBM
The average clinician would benefit from understanding EBM and having tools available
CPGs help standardize care based on EBM
CPGs are becoming a routine part of EHRs
Conclusions