Diagnostic Flashcards
PICO
Patient (population or clinical problem)
Intervention (prognostic factor or exposure)
Comparison
Outcomes
Pyramid for EBM levels of evidence
Meta analysis Systematic reviews RCTs Cohort studies Case control studies Case series and Case reports Animal/laboratory studies
Meta-analysis
a statistical technique that summarizes the results of several studies in a single weighted estimate, in which more weight is given to results of studies with even more events and sometimes to studies of higher quality
Systematic Review
authors of systematic review ask a specific clinical question, perform a comprehensive literature search, eliminate the poorly done studies and attempt to make practice recommendations base on the well done studies
Randomized Control Trial
a trial in which participants are randomly assigned to two or more groups; at least one (experimental group) receives an intervention that is being tested and another (comparison or control) gets an alternative treatment or placebo
Allows assessment of relative effects of intervention
Controlled clinical trial
a trial in which participants are assigned to two or more different tx groups; may refer to controlled trials in which tx is assigned by a method other than random allocation - when the method of allocation is by random selection then it is an RCT
Cohort Study
a non-experimental study design that follows a group of people (cohort) and then looks at how events differ among people within the group - useful for determining if exposure is likely to cause specified events
Prospective are more reliable than retrospective
Case Series
Analysis of series of people with disease (no comparison group in case series)
Optimal study design for treatment or therapy
Meta-analysis
Systematic review
Double blind RCT
Optimal study design for diagnostic
RCT
Controlled clinical trial
Optimal study design for prognosis/etiology/harm
Cohort study
Case control study
Case series
Optimal study design for prevention
RCT
Cohort study
Critical appraisal is
the systematic evaluation of clinical research papers to establish if it..
addresses a clear question
uses valid methods
valid results that are important and applicable to your patient population
Diagnosis is based on
Patient history
Clinical exam findings
Associated diagnostic tests
Successful diagnosis depends on
availability of reliable and valid tests and measures
Test threshold
The probability below which the test will not be performed because possibility is remote
Clinicians must assess probability that a patient has a condition before performing a diagnostic test
Treatment threshold
probability above which a test will not be performed because the diagnosis possibility is great and immediate treatment is indicated
Clinicians must assess probability that a patient has a condition before performing a diagnostic test
Study results - reliability
Verification of reliability is
an acknowledgment that the data captured in a test is composed of the true value and error
Error has to be minimized to avoid false pos or neg
Reliability of the ___ ___ should be indicated in studies of diagnostic tests
Index test
Inter-rater and intra-rater reliability are used to
minimize the threat to research validity referred to as instrumentation
Standard error of measurement can be used on what data
Interval or Ratio
Pearson product moment correlation can be used with what type of data
Interval, Ratio, Comparing two measures
Interclass correlation coefficient can be used with what type of data
Ordinal, Nominal, Compare multiple pairs of measures
Spearmans rho can be used with what type of data
ordinal, nominal, compare two measures
Kappa can be used with what type of data
compare multiple pairs of measures
A valid diagnostic tests
consistently produces true positives or true negatives or both
True positive
+ disorder and test result
True negative
- disorder and test result
False positive
- disorder and + test result
False negative
+ disorder and - test result
Sensitivity
True + over all patients with the condition
The proportion of individuals with the condition that have a pos test result (true pos)
Specificity
True - over all the patients without the condition
The proportion of individuals without the condition who have a negative test result (true neg)
Clinicians use diagnostics tests with high specificity when
knowledge that the patient does NOT have the condition of interest is important
Sn allows a clinician to
determine which test is best to determine if a particular diagnosis is present
PPV
Describes the ability of a diagnostic test to correctly determine the proportion of patients with the disease from all the patients with a positive test
NPV
Describes the ability of a diagnostic test to correctly determine the proportion of patients without the disease from all patients with a negative test
Likelihood ratios
reflect a diagnostic tests ability to provide persuasive information
Advantages to liklihood ratio
Can be calculated for all levels of tests results
Not dependent on prevalence of condition
Can be applied to individuals
P value indicates
the probability that the result obtained occurred due to chance
smaller, the more significant
Confidence intervals represent
a range of scores within which the true score for a variable is estimated to lie within a specified probability
Minimal detectable change
amount of change that just exceeds the standard error of measurement
CAT - was the dx test evaluated in patients like those in whom it would be used in practice
Methods
CAT - was the reference standard ascertained regardless of index test result
Methods
CAT - was there blind comparison btw index test and reference standard
Methods
