Module 1 - Evidence Based Sport Medicine Flashcards
What are Randomized Control Trials?
- Randomly Assigned 2 groups
- One gets intervention, other gets SHAM
- Control for Confounding Variables
- Equal distribution between the groups
What are confounding variables?
- Alternate explanation for an observation
- Must be associated with the exposure and the outcome of interest
- Must not be on causal pathway
What are Case-Control Studies?
- Starts with group of cases
- Look back at history to identify exposures that lead to outcomes
- Compare control and cases to identify unique exposure
- Retrospective
When are Case-Control Studies most useful?
- Great for rare diseases
- Best for rare outcomes
- best for multiple exposures
Why are Case-Control Studies useful? Why arent they?
Useful
- Fast and Cheap
Not Useful
- Weak Evidence
Describe Cohort Studies
- Start with Exposure of Interest
- Find Analogous Group with no exposure
- Look Forward, to see what outcomes emerge
When are cohort studies used?
- Rare Exposures
- Multiple Outcomes
Why are Cohort Studies used? Why not used?
Used
- Good Strong Evidence
Not USed
- Slow and Expensive
What is Sensitivity?
- All the people who are positive for disease that test positive
- True Positive
What is Specificity?
- All the people who are negative for a disease that test negative
- True Negative
What is Selection Bias?
- Error in choosing the individuals or groups to take part in the research
What is Measurement Bias?
- Poorly measuring the desired outcome (e.g. Calibration)
What is Interviewer Bias?
- Opinion/Prejudice/Influence on part of interviewer
- Affects the outcome of research
- May affect interviewees behaviour
What is Response Bias?
- Individual preference/local practices determine subjects are recruited
- More severe cases get sent to academic centres/research studies (thus recruitment comes from them)
What is Reporting Bias?
- Selective reporting or suppression of information or findings (ie. publication bias against negative studies)
Why is Evidence-Based Practice/Medicine important?
- relies on scientific evidence for guidance and decision-making
- Do not rely on Tradition, Intuition, Unproven Methods
What are the levels of Evidence-Based on Study Design?
- 1a. Systematic Review of Randomized Control Trials
- 1b. Individual RCT (narrow confidence intervals)
- 2a. Systematic Review of cohort studies
- 2b. Individual Cohort Study
- 2c. “outcome” Research, Ecological Studies
- 3a. Systematic Review of case-control studies
- 3b. Individual Case-control study
- Case-series
- Expert Opinion
What are all Studies categorized into?
- Descriptive
- Analytic
What are the two types of Descriptive Studies?
- Survey
- Qualitative (interview/questionnaire)
What are the two types of Analytic Studies?
- Experimental
- Observational Analytic
What are the two types of Experimental Studies?
- Randomized Parallel Groups
- Randomized Crossover
What are the 3 types of Observational Analytic Studies?
- Cohort Study
- Cross-sectional
- Case-control study
What does PICO Stand for?
P - Patient
I - Intervention
C - Comparison
O - Outcome
Describe the P in PICO
Patient
- Sex, gender, age, race
- Primary complaint
- disease History
Describe the I in PICO
Intervention
- What do you want to do for them?
- Prescribe a drug?
- Order a test?
Describe the C in PICO
Comparison
- To what alternatives do you want to compare the intervention?
Describe the O in PICO
Outcome
- What do you hope to accomplish, improve or affect?
- Relieve or reduce symptoms?
- Improve Function or Improve Test Scores?
What are the first questions to ask when identifying the aim of the study?
- Does it describe a population? = descriptive
- Does it quantify the relationship between factors? = Analytic
What question do you ask if the study is analytic?
Was the intervention randomly allocated?
- Yes = Randomized control trial
- No = Observational Study
How are Observational Types determined?
- Ask when the outcomes were determined
How does the outcome timing determine the observational study types?
- After exposure: Cohort Study
- At the same time as exposure: Cross-sectional Study
- Before Exposure was determined: Case-Control Study
What are the advantages of a Randomized Control Trial?
- Unbiased Distribution of Confounders
- Blinding More Likely
- Randomisation Facilitates Statistical Analysis
What are the Disadvantages of a Randomized Control Trial?
- Expensive: time and money
- Volunteer Bias
- Ethically problematic at times
What are the advantages of a Crossover Design?
- All subjects serve as their own controls and error variance is reduced thus reducing the sample size needed
- All subjects receive treatment (at least some of the time)
- Blinding can be maintained
What is a crossover design?
- Each study participant has both therapies
- Randomized treatment to Group A first, then to Group B later
- Only relevant if the outcome is reversible with time
What are the disadvantages of a Crossover Design?
- All subjects receive a placebo or alternate treatment at some point
- Washout period lengthy or unknown
- Cannot be used for treatment with permanent effects
What are the advantages of a case-control study?
- Quick and Cheap
- Only Feasible Method for very rare disorders with long lag between exposure and outcome
- Fewer subjects needed than cross-sectional studies
What are the disadvantages of a case-control study?
- Reliance on recall or records to determine exposure status
- Confounders
- Selection of control groups is difficult
- Potential bias: recall and selection
What are the advantages of Cohort Studies?
- Ethically Safe
- Subjects can be matched
- Can Establish timing and directionality of events
- Eligibility criteria and outcome assessment can be standardised
- Administratively easier and cheaper than RCT
What are the disadvantages of a cohort study?
- Controls may be difficult to identify
- Exposure may be linked to a hidden confounder
- Blinding is difficult
- Randomisation not present
- For rare disease, large sample sizes or long follow-u necessary
What is a True Positive?
- Sick people correctly diagnosed as sick
What are false positives?
- Healthy people incorrectly identified as sick
What are true negatives?
- Healthy people are correctly identified as healthy
What are False Negatives?
- Sick People incorrectly identified as healthy
What is the equation for identifying Sensitivity in a test?
- True Positive / All cases of the condition (true positive + false neg)
What is the equation for identifying specificity in a test?
- True Negative / All non-cases of the condition (true neg + false positive)
What does the term SPIN and SNOUT mean?
SPIN
- SPecific rules IN
SNOUT
- SeNsitive rules OUT
What are tests with high sensitivity good for? example?
Good for:
- ruling condition out
Example
- Bone Scan for Stress Fracture
- Negative bone scan = confident that no fracture
What are tests with high specificity used for? example?
Used for
- Ruling conditions out
Examples
- CT scan for a stress fracture
- Positive CT scan = confident of fracture
What are Surrogate Outcomes? examples?
- Laboratory Measure/physical intended as a substitute for a clinically meaningful endpoint
- Changes to surrogate endpoint = reflect changes in a clinically meaningful endpoint
ex - Blood pressure change
What are Clinically Meaningful Endpoints? example?
- Direct measure of how an individual feels, functions, or survives
ex. - Reduction in pain
