Vanderbilt Sports Medicine

Chapter 5: Therapy, Part 2

Thomas F. Byars

Evidence-Based MedicineEvidence-Based MedicineHow to Practice and Teach EBMHow to Practice and Teach EBM

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Qualitative literature

Qualitative research may provide us with some guidance in deciding whether we can apply the findings from quantitative studies to our patients

It allows us to interpret clinical phenomena through an emphasis on understanding the experiences and values of our patients

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Is the evidence valid, important, and applicable?

1. Was the selection of participants explicit and appropriate?

• Appropriate in the sense of representative of the population we are interested in and who are relevant to the study question

2. Were the methods used for data collection and analysis explicit and appropriate?

• Direct observation, interviews, focus groups, etc; blinding may limit investigators interpretation of data

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Is the evidence valid, important, and applicable?

3. Are the valid results important, are they impressive?• Sufficient detail for us to obtain a clear picture of the

phenomena described

4. Are these valid important results applicable to my patient?• Do we think these same phenomena apply to our

patient?

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Systematic Reviews

Summary of medical literature that uses explicit methods to systematically search, critically appraise, and synthesize the world literature on a specific issue

Goal is to minimize both bias and random error

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Is the evidence from this SR valid?1. Is this a SR of randomized trials?

By combining all relevant randomized trials, they further reduce both bias and random error, providing the highest level of evidence available

2. Does it describe a comprehensive and detailed search for relevant trials?

3. Were the individual studies assessed for validity?

Methods of randomization, blinding, similar groups, sufficient f/u, etc

4. Were individual patient data (or aggregate data) used for the analysis?

Individual patient data allows you to test promising subgroups from one trial in an identical subgroup from others

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Is the evidence from this SR important?

1. Are the results consistent across studies?

We’d be more likely to believe the results if every trial shows a treatment effect that is at least going in the same direction; ideally, investigators should test their results to see whether any lack of consistency was not from chance alone

2. What is the magnitude of the treatment effect?

Clinical usefulness of NNT (NNH) and conversion of ORs and RRs

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Is this valid, important evidence from this SR applicable to my patient?

1. Is our patient so different from those in the study that its results cannot apply?

2. Is the treatment feasible in our setting?

3. What are our patient’s potential benefits and harms from the therapy?

4. What are our patient’s values and expectations for both the outcome we are trying to prevent and the adverse effects we may cause?

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Clinical Decision Analyses

• Applies explicit, quantitative methods to compare the likely consequences of pursuing different treatment strategies, and integrates the risks of benefit and harm associated with the various treatment options with values associated with the treatments and with potential outcomes

• Starts with a diagram called a decision tree, illustrating the target disorder, alternative treatment strategies and their possible outcomes

• The “winning” strategy, and preferred course of action, is the one that leads the highest utility (measure of a person’s preference for a health state; usually decimal from 0-1 and typically 1= perfect health, 0=death)

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Is this evidence from a CDA valid?

1. Were all therapeutic alternatives (including no treatment) and outcomes included?• Should include all treatment strategies and full range of

outcomes (good and bad)

2. Are the probabilities of the outcomes valid and credible?• There may be some uncertainty around a probability

estimate, but authors should specify a range

3. Are the utilities of the outcomes valid and credible?• Ideally, utilities are measured in patients using valid,

standardized methods

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Is this valid evidence from a CDA important?1. Did one course of action lead to clinically important

gains?2. Was the same course of action preferred despite

clinically sensible changes in probabilities and utilities?

Is this valid and important evidence from a CDA applicable to our patient?

1. Do the probabilities in this CDA apply to our patient?2. Can our patient state his/her utilities in a stable, usable

form?• Generate utilities for our pt and determine if they fall w/in the

range tested in the CDA

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Economic analysesCompare the costs and consequences of different management

decisions; consider “opportunity costs”Is this evidence from a economic analysis valid?

1. Are all well-defined courses of action compared?2. Does it provide a specified view from which the costs and

consequences are being viewed?• Patient, hospital, local gov’t

3. Does it cite comprehensive evidence on the efficacy of alternatives?

4. Does it identify all the costs and consequences we think it should and select credible and accurate measures of them?• Direct and indirect costs

5. Was the type of analysis appropriate for the question posed?• cost minimization analysis, cost-effectiveness analysis, cost-

benefit analysis, etc.

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Is this valid evidence from an economic analysis important?

1. Are the resulting costs, or cost per unit of health gained, clinically important?• Does the intervention provide a benefit at an acceptable cost

2. Did the results of this economic analysis change with sensible changes to costs and effectiveness?

Is this valid and important evidence from an economic analysis applicable to our patient?

1. Do the costs in the economic analysis apply in our setting?

2. Are the treatments likely to be effective in our setting?

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Clinical Practice Guidelines

Systematically developed statements to help clinicians and patients with decisions about appropriate health care for specific clinical circumstances

Before considering using one, think of it as having two distinct components:

1. Evidence summary (“avg effect of this intervention on the typical pt who accepts it”) and

2. Detailed instructions for applying that evidence to our patient

Valid guidelines create their evidence components from systematic reviews of all the relevant worldwide literature

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Guides for deciding whether a guideline is valid and applicable to my pt/practice/hospital

1. Did it’s developers carry out a comprehensive, reproducible literature review within the past 12 months?

2. Is each of it’s recommendations both tagged by the level of evidence upon which it is based and linked to a specific citation?

3. Applicability of a guideline depends on the extent to which it is in harmony or conflict with four local factors: Killer B’s

1. Is Burden of illness too low to warrant implementation?2. Are the Beliefs of individual pts or communities about the value of

the interventions or their consequences incompatible with the guideline?

3. Would the opportunity cost of implementing this guideline constitute a bad Bargain in the use of our energy or our community’s resources?

4. Are the Barriers (geographic, traditional, behavioral, etc.) so high that it is not worth trying to overcome them?

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N-of-1 Trials

Important points/pitfalls associated with a “trial of therapy”:1. Some target disorders are self limited2. Both extreme lab values and clinical signs, if left untreated,

often return to normal3. A placebo can lead to substantial improvement in symptoms4. Both our own and our pts expectations about the

success/failure of a treatment can bias conclusions about whether a treatment actually works

5. Polite pts may exaggerate the effects of therapy

N of 1 trial is employed when there is significant doubt about whether a treatment might be helpful in a particular pt, and is most successful when directed toward the control of symptoms or relapses from a chronic disease