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Flashcards in Summarized Resources Deck (33):

What are the 4 A's of evidence based medicine?

Ask, Acquire, Appraise, Apply


The highest level of evidence, the evidence that is most valid (free of bias)

"Best" Evidence


Biased samples, unrealistic methods, and Berkson's bias all affect

External Validity


Bias from subjects or investigators, extraneous factors, and lack of randomization all affect

Internal validity


Synthesize results and pull together major findings

"Review" Articles


Review articles can be found in many

Clinical journals


The strength of review articles are that, if done well, they provide a good discussion from experts in the field on the most important findings and

New directions


What are the weaknesses of review articles?

They are subject to the bias of the author or the journal


Reviews of the literature that follow a prescribed protocol to remove bias

Systematic reviews


Save time and find and summarize the best evidence (When done well)

Systematic reviews


Provide up to date summary of all published research literature and allow large amounts of data to be assimilated

Systematic Reviews


Where do you find systematic reviews?

Peer-reviewed journals, or databases (Cochrane library)


Systematic reviews define a specific



Find all scientific studies, select the strongest studies, and describe the scientific strength of the selected studies

Systematic reviews


In a systematic review, the specific question is defined using


Patient (population)
Intervention (exposure, test, or other agent)
Comparison (other treatment/group)
Outcome (outcomes of clinical importance)


You have a patient who is trying to lose weight and has decided to take up running, in hopes of running a marathon in the next year. She has a trainer, who recommends that she prevent muscle soreness by using a new whole-body cryotherapy machine that was bought by the gym. The trainer says it will prevent muscle soreness. She asks whether it would prevent muscle soreness, and whether it would be good for her. What is the PICO?

Patient = Adults
Interventions = Whole-body cryotherapy
Comparisons = Nothing, or other non-drug txs
Outcomes = amount of muscle soreness


A 52 year old man reports to E.D. complaining of
worsening epigastric pain for 1 day with chronic
pain for 3 months. Nausea and vomiting for 1 day,
and no bowel movement for 1 day. History of
similar attacks increasing in frequency over the
past 3 years. Significant history of ongoing alcohol
abuse. No recent trauma. He is diagnosed with acute pancreatitis and says that he read that enteral feeding (tube feeding) may be better than the intravenous feeding. He asks you what you think. What is the PICO?

Patient = adult with severe acute pancreatitis
Intervention = Enteral Feeding
Comparison = IV feeding
Outcome = Survival, disease severity, complications?


On her routine visit to assess her asthma control, Ms. S, your 23 year old patient with persistent asthma, says that she recently heard that drinking coffee makes asthma better. She normally takes asthma control medicine and uses an inhaler a few times a week when she has a severe episode. She would like to know if drinking more coffee will reduce her need to use her inhaler. What is the PICO?

Patient = Adult asthma patients
Intervention = regular asthma medication plus coffee
Comparison = regular asthma medication alone
Outcomes = reduction in asthma symptomes and reduced use of inhaler


A large, multi-site study is published that examined the effectiveness of a new drug to promote hamstring muscle healing after a strain. 100 subjects from 10 sports medicine centers are chosen and randomly assigned to receive the drug or placebo. The drug was found to work and have an added benefit. What would be an example of an extraneous factor that would be important to control in order to increase the internal validity of the study?

Whether people in the drug group were using other forms of medication such as non-steroidal anti-inflammatories


In a systematic review, the purpose of finding all relevant studies and selecting the strongest studies is to get a

Representative sample


The goal to finding all the studies bearing on a question is to

Increase sensitivity and reduce bias


What are some methods to choosing the strongest articles?

Limit to RCTs and avoid observational trials, or those without a comparison group


You should always include unpublished studies to avoid

Publication bias


Bias towards publishing only positive outcomes

Publication bias


A systematic review aims at examining internal validity by reviewing for bias and making sure the review includes more than one



Determining the scientific strength of the selected studies and if quality is associated with results is how systematic reviews examine

Internal validity


Weaker studies tend to have better

Effect sizes


In a Forest-plot, the size of the square is proportional to the

Number of people in the sample


In a Forest-plot, the line length represents the

CI (larger means more variability/error)


If results are similar, they can be pooled and analyzed together in a



Pooled results are weighted by sample size. What are the two models?

Fixed effect model and random effect model


When studies ask the same question

Fixed effect model


Assumes studies are asking different questions but are somewhat similar

Random effect model

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