EBP Exam 2

pubmed

free search engine accessing medline database

PEDro

PT focused database search engine

Cochrane library

provides a database of systematic reviews and meta-analysis

primary sources

provide original research reports (ex. peer-reviewed journals, conference proceedings, these/ dissertations)

secondary sources

contain information based on primary sources (ex. textbooks, summaries on websites, review papers)

systematic review

summarize the evidence according to a pre-defined inclusion/ exclusion criteria

met analysis

use statistical method to summarize the results of the included studies

foreground questions

questions that will help PTs make decisions on management of care

background questions

focus on medical aspect rather than on PT component

PICO

population, issue, comparison, outcome

PIRT

population, issue, reference standard, target condition

MeSH

medical subject headings, controlled vocab or terms assigned to records to make them discoverable

diagnosis

a process in which patient data are collected and evaluated to classify a condition, determine prognosis and identify possible interventions

successful diagnosis depends on using tests that are...

reliable, valid and persuasive

what is the best evidence for diagnostic tests?

blind comparison of an index test and a reference standard of diagnosis in an appropriate spectrum of consecutive patients

four steps of diagnostic appraisal

applicability, credibility (internal validity), study results (statistical results), application of evidence

study applicability

is the sample in the study similar enough to my patient to justify the expectation that my patient will respond similarly enough to the sample (close enough is good enough)

spectrum bias (selection bias)

refers to the phenomenon that the performance of a diagnostic test may vary in different clinical settings b/c each setting has a different mix of patients (ideally you want consecutive sampling)

verification bias

only some patients get the reference standard

study credibility (7 questions for internal validity)

1.) Did the investigators (they) include subject w/ all levels/ stages of the condition evaluated by the index test?
2.) Did they evaluate the reliability of the index test?
3.) Did they compare results from the index test to results from a gold standard comparison?
4.) Did all subjects receive both tests regardless of test outcomes?
5.) were the individuals performing and interpreting each test's results masked/ blinded
6.) was the time b/n application of the index test and the gold standard comparison test short enough to minimize opportunity for change
7.) did the investigators confirm their findings w/ a new set of subject?

application of evidence to your patient

can you perform the index test safely given your knowledge, skill and resources, does the index test fit w/in the patients expressed values/ preferences, will you use the index test for this patient/ client

sensitivity

the proportion of individuals w/ the disease/ injury who have a positive test result (aka true positives)

specificity

the proportion of individuals w/o the disease/ injury who have a negative test result (aka true negatives)

PPV

the probability of the target disorder in participants w/ a positive test

NPV

the probability of not having the target disorder in participants w/ a negative test result

LR+

shows how many time more likely patients w/ the target disorder are to have a positive test result than patients w/o the target disorder

LR-

shows how many times less likely patients w/ the target disorder are to have a negative result than patients w/o the target disorder

LR+ > 10

strong positive test result

LR- < 0.1

strong negative test result

LR = 1

indicates the test is of little use

prevalence (pre test probability)

number of patients w/ the target condition in the entire population-- the probability of having the target disorder before performing the test

what does Sn/ Sp tell you

how many subjects w/ and w/o the target disorder a test can identify

what do predictive values and LR tell you

how much more likely the target condition is, given a certain test result

why are predictive values and likelihood ratios mostly used in clinical practice

b/c you use Sn/ Sp of the test before you use it on patient

SnNout

if you use a test that has a very high Sn and the test is Negative, the test is good at ruling OUT the diagnosis (if the Sn is high false negatives are unlikely)

SpPin

if you use a test that has very high Sp and the test is Positive, the test is good at ruling IN the diagnosis (if Sp is high false positives are unlikely)

why do you need ROC curve

to find the optimal threshold when there is a high Sn and low 1 - Sp (high Sp)

AUC of 1

perfectly accurate test

AUC 0.5

no discrimination test w/ results equal to chance

barriers to using the evidence

1.) lack of time
2.) inability to understand stat data
3.) lack of support from employer
4.) lack of resources
5.) lack of generalization of results

clinical practice guideline

direct recommendations-- systematically developed statements designed to facilitate evidence based decision making for the management of specific health conditions

intent of a CPG

improve efficiency and effectiveness of health care through the use of summary recommendations about patient/ client management

strengths of CPGs

informed by a systematic review of literature, provide recommendations to optimize care, assess benefits and harms, change behavior/ practice

grading of literature

I (strongest), V (weakest)

grading of evidence

A (strongest), F (weakest)

0.5 < AUC < 1

imperfect but useful test