Evidence Based Medicine

The ratio of the risk of an event among an exposed population to the risk among the unexposed.

Relative Risk (RR) or Risk Ratio

Which of the following are decision approaches that attempt to ensure the decision consistent with patient values and preferences

Shared decision making approach Informed decision making approach Clinician-as-perfect-agent approach

Which of the following are reasons why RCTs may not be helpful for determining whether a putative harmful agent truly has deleterious effects (select all that are correct)?

Study reports of RCTs sometimes fail to adequately provide information on harm When we are concerned about rare and serious adverse effects When it is unethical to randomize patients to exposures that might result in harmful effects without benefit When the duration of follow-up is too limited

Select all the statements that apply to the GRADE approach.

The Cochrane Collaboration has adopted the GRADE approach. The GRADE Working Group is a group of health care professionals, researchers, and guideline developers who worked to develop an optimal system of rating confidence in estimates for systematic reviews and health technology assessments of questions of the impact of interventions and to determine the strength of recommendations for clinical practice guidelines. The GRADE approach has been disseminated widely and endorsed by more than 70 organizations worldwide.

In a simplified illustration of decision analysis, which of the following are true.

The decision is represented by a square, termed "decision node" Circles or "chance nodes" symbolize the different events that can occur after each clinical strategy. The lines that emanate from the decision node represent the clinical strategies under consideration. Triangles or rectangles identify outcome states.

When examining evidence of harm, we need to consider which of the following when making the decision to use a particular therapy (select all correct answers):

The risk of bias in the evidence The relevance of the evidence to patients The strength of the association between the cause and the adverse outcome in the evidence

A decision-making approach with minimal or no attempt to ensure decision consistent with patient values and preferences is called the paternalistic approach.

True

A drawback of traditional pairwise meta-analysis is that it evaluates the effects of only 1 intervention vs 1 comparator and does not permit inferences about the relative effectiveness of several interventions

True

A well-constructed decision aid offers a tested and effective way of communicating information to patients who may have little background in quantitative decision making.

True

Three principles of EBM

1. Optimal decision making requires awareness of the best available evidence 2. Not all evidence is equal. 3. Evidence alone is never enough

Select all the statements that apply to forest plots.

A forest plot provides a visual representation of the best estimate of effect and the range of plausible truth (confidence interval) for each study. A vertical line in the forest plot represents no effect. A forest plot provides a pooled estimate combining all studies. A forest plot is a graphic display that illustrates the magnitude of effect of an intervention versus a control in several studies.

Select the most common grading systems for recommendation in practice guidelines?

AHA (American Heart Association) GRADE (Grading of Recommendations Assessment, Development and Evaluation) USPSTF (US Preventive Services Task Force)

A common name for the rule that guides clinicians in simultaneously considering all of the important prognostic factors is called:

Clinical decision rule

An example of this type of bias is when research describing the outcomes of patients in tertiary centers may not be applicable to the general patient with the disorder in the community .

Referral

Evidence literacy include which of the following (select all correct answers):

Ability to define the reference standard Ability to recognize threats to claims that a test detects a health condition

Applicability of results

An example includes the following question: "Will patients be better off as a result of the new test?"

When applying the results of the evidence to a patient care situation, which of the following are important considerations (select all that are correct)?

Are there benefits that offset the risks? What is the incremental risk? Was the follow-up sufficient? Is the exposure similar to what may occur in my patient?

Five A's of EBM

Ask, Acquire, Appraise, Apply, Act

_______ is the optimal strategy for maintaining prognostic balance.

Blinding

When putting the 5 A's of EBM into practice, which of the following questions are asked during the Appraise process (select all correct answers):

Can the information be trusted? What are the results? How serious is the risk of bias?

Which of the following provides an answer to the question: " "Given the observed difference between experimental and control groups, what is the plausible range of differences within which the true difference might actually lie?"

Confidence interval

Most clinical decision analyses are built as ____________.

Decision trees

What is EBM?

EBM is integration of best available evidence with clinical expertise and patient values and preferences. Evidence, circumstances, values, in context

Evidence serves to ________________ confidence in a particular claim

Enhance or diminish

To estimate a patient's prognosis, we examine outcomes in groups of patients with a similar clinical presentation and then refine our prognosis by:

Examining co-morbidities Examining subgroups defined by demographic variables

Case series (descriptions of a series of patients) and case reports (descriptions of individual patients) do not provide any comparison groups, but it is still possible to determine whether the observed outcome would have occurred in the absence of the exposure

False

Case-control studies are always prospective in design

False

Decision analysis is an informal methodology that integrates the evidence regarding the beneficial and harmful effects of treatment options with the values or preferences associated with those effects.

False

Evidence alone is enough to allow decision-makers balance risks and benefits of alternative management strategies

False

The US Food and Drug Administration (FDA) has produced a statement indicating that noninferiority trials will not be accepted as evidence of a drug's effectiveness and safety.

False

The pooling of studies increases precision (i.e., widens the confidence intervals [CIs]), and the single best effect estimate generated facilitates clinical decision making.

False

Variables or factors that influence whether patients with a disease (or medical condition) do better or worse are called risk factors.

False

When assessing treatment recommendations, which of the following questions should be considered?

For weak recommendations, does the information provided facilitate shared decision making? Were all of the relevant outcomes important to patients explicitly considered? Is the recommended intervention clear and actionable? Are values and preferences associated with the outcomes appropriately specified?

The usual approach to using (appraising) an article from the medical literature using JAMAEvidence principles includes asking the following quiestions:

How serious was the risk of bias? What are the results? How can I apply the results to patient care?

Which of the following statements are true regarding confidence in systematic reviews.

Randomized trials are initially assigned high confidence and observational studies are given low confidence, but a number of factors may modify these initial ratings. Confidence ratings begin by considering study design An increase in confidence rating is uncommon and mainly occurs when the effect size is large, Confidence ratings may decrease when there is increased risk of bias, inconsistency, imprecision, indirectness, or concern about publication bias.

Which of the following are reasons to seek a systematic review, especially one that includes a meta-analysis, rather than using the best individual study or studies.

If the systematic review is performed well, it will likely provide all of the relevant evidence with an assessment of the best estimates of effect and the confidence they warrant. Single studies are liable to be unrepresentative of the total body of evidence, and their results may therefore be misleading. Systematic reviews include a greater range of patients than any single study, potentially enhancing your confidence in applying the results. Collecting and appraising a number of studies takes a lot of time. A systematic review is often accompanied by a meta-analysis to provide the best estimate of effect that increases precision and facilitates clinical decision making.

Likelihood ratio

If you are trying to determine how well a test performs, find how much a given result will shift the belief that the problem exists

Three functions of EBM

Knowing, doing, and understanding

A ratio of the odds of an event in an exposed group to the odds of the same event in a group that is not exposed.

Odds Ratio (OR) (or relative odds)

The key principles of EBM include (select all correct answers):

Optimal clinical decision making requires awareness of the best available evidence Not all evidence is equal

Evidence-based medicine (EBM) involves conscientiously working with patients to help them resolve or cope with problems related to their:

Physical, mental, and social health

Which of the following is true regarding practice guidelines?

Practice guidelines are statements that include recommendations intended to optimize patient care. Guideline panels should providethe key information on which their recommendations are based. To make a recommendation, guideline panelists must define clinical questions, select the relevant outcome variables, retrieve and synthesize all of the relevant evidence, rate the confidence in the effect estimates, and, relying on a systematic approach but ultimately also on consensus, move from evidence to recommendations.

According to your text, when using the probabilistic analytic approach, expert diagnosticians generate a list of potential diagnoses, estimate the __________ associated with each, and conduct __________, the results of which increase or decrease the __________, until they believe they have found the best answer to fit the patient's illness

Probability, investigations, probabilities

According to your text, clinicians help patients in 3 broad ways: (1) diagnosing or ruling out medical and health-related problems, (2) administering treatment that does more good than harm and (3) giving them an indication of what the future is likely to hold.

True

Clinicians can evaluate the precision of the estimate of risk by examining the confidence interval (CI) around the estimate

True

Cohort studies may be prospective or retrospective.

True

Even if the prognostic result does not help with selection of the appropriate therapy, it can help you in counseling a concerned patient or relative.

True

Heterogeneity is defined as differences amongst individual studies included in a systematic review, typically referring to study results; yet the term can also be applied to other study characteristics.

True

Ideally, at the conclusion of a trial, investigators will know the status of each patient with respect to the target outcome. The greater the number of patients whose outcome is unknown—patients lost to follow-up—the more a study is potentially compromised

True

If a patient is at low risk of adverse outcomes, even beneficial treatments may not be worthwhile.

True

In answering a clinical question, the first goal should be to identify whether a systematic review of the topic exists that can provide a summary of the highest-quality available evidence

True

Investigators who lose track of a large number of patients increase the risk of bias associated with their prognostic study. The reason is that those who are followed up may have systematically higher or lower risk than those not followed up.

True

The I2 statistic is a preferred alternative approach for evaluating heterogeneity that focuses on the magnitude of variability rather than the statistical significance of variability.

True

The NMA approach provides estimates of effect sizes for all possible pairwise comparisons whether or not they have actually been compared head to head in RCTs.

True

The direction and magnitude of the change from the pre-test to the post-test probability are determined by the test's properties and the performance property of most value called the likelihood ratio.

True

When a decision analysis includes costs among the outcomes, it becomes an economic analysis and summarizes trade-offs between health changes and resource expenditure

True

When designing noninferiority trials, investigators set their own thresholds, typically using statistically based criteria.

True

When expressing the association between an exposure and an outcome in a case-control study, we should use a ratio of odds (OR or odds ratio) rather than a ratio of risks (RR)

True

With respect to validity, assessment of a noninferiority study requires special attention to the optimal use of the standard treatment.

True

You may see a published systematic review in which the authors chose not to do a meta-analysis, and you may see a meta-analysis conducted without a systematic review.

True

When appraising diagnostic study evidence, which questions pertaining to the reference standard should be asked (select all correct answers):

Was an acceptable reference standard used? Were the test and standard independent? Were the test and standard results assessed blindly?

Accurate does NOT equal Useful

Whether a test is helpful depends on your perspective and values

Reference standard

You cannot decide if a test works unless you find or create a _________: the best available way of determining whether what you are looking for is present

It is calculated as the risk in the control group minus the risk in the experimental group

absolute difference

The risk of an event

absolute event

The absolute difference (risk difference) in risks of harmful outcomes between experimental groups and control groups, calculated as the risk of harmful outcome in the control group minus the risk of harmful outcome in the experimental group

absolute risk reduction (ARR)

GRADE approach

allows you to rate confidence in estimates of effects. also takes into account bias

Clinicians require studies of prognosis—those examining the possible ___________ of a disease and the probability with which they can be expected to occur.

outcomes

The power of randomization is that treatment and control groups are more likely to have a balanced distribution of known and unknown ________ factors.

prognostic

Randomized clinical trials provide less biased estimates of potentially harmful effects than other study designs because ____________ is the best way to ensure that groups are balanced with respect to known and unknown determinants of the outcome

randomization

If a large number of variables have a major effect on prognosis, investigators should use statistical techniques, such as _________ analysis, to determine the most powerful predictors.

regression

Blind data analysts

to avoid bias in decisions regarding data analysis

Blind patients

to avoid placebo effects

Blind data collectors

to prevent bias in data collection

Blind adjudicators of outcome

to prevent bias in decisions about whether or not a patient has had an outcome of interest

Blind clinicians

to prevent differential administration of therapies that affect the outcome (cointervention)