EBM Flashcards
3 main issues address when undergoing critical appraisal
Validity, the results, the clinical relevance
validity
how trustworthy the study is, does it measure what its supposed to. Minimising bias improves validity
Results
What does this show, is it statistically significant, size of the effect. (only worth thinking about implications of results if study design and methods are valid)
Clinical relevance
will the results help you and your patient. Differences between patient and participants identified to see effectiveness.
Whats involved in the critical appraisal checklist, what are the 6 questions
Was the study original?(does it add anything to current literature) Who was the study about? (how were Ps recruited/inclusion exclusion criteria) Was the study design sensible? Was bias avoided? (control group used, randomisation, other sources) Was assessment blind? Were preliminary statistical questions addressed? (size of sample, followup) different checklists are used for different study types.
Critical appraisal skills programme (CASP)
provides critical appraisal checklists that are designed to help you think about aspects of appraisal systematically.
CONSORT
focuses on RCT and aspects that should be included. Can be used to critically evaluate or design.
STROBE
helps design and appraise observational studies
Hierarchy of evidence
SR and MA. RCT. Cohort. CC. Cross sectional. Ecological. Case reports. Ideas and opinions.
GRADE
grading and recommendations assessment, development and evaluation. ranks quality of evidence. GRADE and SIGN take into account more dimensions.
PICO
patient, intervention, comparison, outcomes.
Reaching a decision about a paper
Reject it, interpret the results cautiously, accept it/trust.
Pre trial Bias
selection bias. not representative of the population. groups differ from each other.
Channeling bias - patient prognostic factors or degree of illness dictates the study cohort into which patients are placed
During trial bias
information bias. errors in measuring exposure, intervention or outcome.
interviewer. Chronology. Recall. Transfer. Performance
Post trial bias
confounding. statistical bias - misleading conclusions.
Citation. Internal/external validity.
ANOVA
(Analysis of Variance) is used for more than two treatment groups.
unpaired t test
difference between means of 2 groups
Chi squared
The Chi-square (χ2) test is used to determine if observed frequency counts differ from expected frequency counts
linear and logistic regression
Used to assess how one or more predictor variables can be used to predict a continuous outcome variable.
Allows us to ‘adjust’ for the effects of confounding variables.
“Do age, gender, and comorbidities predict distance walked in 2 minutes following physiotherapy?”
Used to assess the predictive value of one or more variables on a binary outcome variable.
Also allows adjustment for effects of confounders.
“Do age, gender, and comorbidities predict which stroke patients will show improvement following physio?”
CAM
therapies/interventions that are: non-standard / unconventional
non-prescription
non-surgical
(can be pharmacological or non-pharmacological)
how is CAM not conventional
may not have had rigorous testing. efficacy hasnt been demonstrated, nor safety. Health care professionals wouldnt recommend.
Placebo and the placebo effect
Placebo = Any therapy which has no specific activity for the condition being treated e.g., sugar pill: a biologically inert, inefficacious substance.
The placebo effect = Any non-specific psychological or psychophysiological effect produced by placebos.
This non-specific effect can be worked out by excluding the known specific effects of the treatment under investigation.
How does the placebo effect work
outcome expectancies. Patiant related self efficacy expectancies. Symbolic effect of treatment. Anxiety reduction.
Potential benifits of CAM
can improve non motor symptoms like sleep mood GI. Via placebo effect, stress reduction, improved mood/sleep. greatr locus of control.
Potential harmful effects of CAM
Used as an alternative. Unregulated. can be harmful - side effects, interactions with prescribed. Expensive.
