Presentation on theme: "Evidence based medicine and clinical practice"— Presentation transcript:
1 Evidence based medicine and clinical practice Dr. J Tumbo
2 Evidence-based clinical practice Is an approach to decision-making in which the clinician uses the best evidence available, in consultation with the patient, to decide upon the option which suits that patient best.The Evidence-based Medicine Triad Source: Florida State University, College of Medicine.
3 What is EBPThe conscientious use of current best scientific research in making decisions regarding care of a particular patient.It integrates current best knowledge with practitioner’s experience and patient values.It is the link between research and patient careOptions exist of using evidence from primary studies or pre- appraised publications e.g. The Cochrane, Evidence that matters
4 Clinical Questions/situations addressed in EBP Therapeutic: questions about treatment that would be given to a patient and the treatment outcomes of the different optionsDiagnostic: questions about the degree to which a particular test is reliable in picking the conditionPrognostic: questions about a patient’s future health, lifespan and quality of life in the event that he chooses a particular treatment option or is affected by a specific condition
5 5 steps Formulate an answerable question Track down the best evidence Critically appraise the evidence for validity, clinical relevance and applicabilityIndividualize, based clinical expertise and patient concernsEvaluate your own performance (clinical audit)Assess your patientAsk clinical questionsAcquire the best evidenceAppraise the evidenceApply evidence to patient care
6 Characteristics of answerable question (PICO) Patient or Problem or Population – Describes your patient, problem or population: ask “how would I describe a group of patients similar to mine?”Intervention – Activity or process related to the patient : ask “which main intervention am I consideringComparison intervention (if appropriate) – ask “what is the main alternative to compare with the intervention”Outcome (s) – End result of activity or intervention: ask “what can I hope to accomplish?”
7 A. Asking the questionThe creation of a question from the clinical scenario is the first crucial step in searching for an answer.It arises from a comprehensive assessment of the clinical situation.Guided by clinical tasks relevant to the scenario
8 Example of questionWhat is the risk of development of Cancer of the Breast in a 52 year old woman using estrogen-only pills as hormone replacement therapy.
9 B. Acquiring the best evidence Tracking down the best evidence can be manual or computerised.Computerised literature search needs skill in searching.Needs for reliable sites e.g. PubMedUse of key words (not the whole question) in the search boxRefine the search by filters to narrow down available literature and getting full text articles
10 Refining the searchBoolean operators: conjunction words that link or exclude the key words. Common Boolean operators include AND, OR, NOT.Using LIMITS to narrow the search finding. One may limit the search on the various attributes that include “Human or animal studies”, Gender, Age, Year of publication, research type and even the specialtyTruncating mean the use of a asterix * as suffice to part of a word that may end in multiple ways. For example, if Bacter* is entered as a key word, the computer will search for all words starting with bacter that include Bacteria, Bacteriology, Bacterium etc.Use synonyms (words which has the same meaning as another e.g. Manager and Executive, Woman and Female).Related links/citationsMESH database
12 Hierrhachy of evidence in epidemiological studies CausalitySystematic reviews/meta-analysisRandomized controlled trialCohort studiesCase control studiesCross sectional studiesCase reportAnecdotesAssociationDescriptive
13 Case report/seriesDescriptive study of an experience or occurrence in one or many individualsIndividual patients Patient notes Combined notes Case report
14 Cross sectional studyDescriptive study of observation or measurement of characteristics of a defined population at a specific point in time. No follow-upPopulation observation describe results
15 Case control studyBefore exposure Hx of past exposure Cases/controls with/out diseaseCompare historiesDraw conclusionExposure relative to outcome
16 Cohort studyStudy of group or groups with no disease in the beginning. Exposure and follow-up is done prospectively then measurement of outcomeCohorts start Exposure/Followup cohort at end OutcomesCompare outcome e.g.CANCER OF BRONCHUS
17 Randomised controlled trial Analytical study in which study participants are randomly assigned to exposure by researcher then followed up to identify outcomePopulation randomisation exposure followup outcomeCompare results
19 What Is a Systematic Review? Systematic reviews are scientific investigations in themselves, with an a priori protocol(pre-planned methods) and an assembly of original studies as their "subjects."They synthesize the results of multiple primary investigations by using strategies that limit bias and random error
20 What is a meta-analysis Enhance precision by pooling smaller studies (to artificially create one large study)to arrive at a common estimate with a certain level of certainty
21 Perform a search on PubMed Subject searchingYou are challenged by the huge number of pregnant women presenting with PET. You recall that APRIRIN could be used to prevent PET. However there are differing opinions on this. How will you proceed
22 Search the Cochrane Library International Cochrane Collaboration>90 countrieseffects of interventionsIncludes:Full-text Systematic ReviewsAbstracts to further SRs and RCTsAvailable at:
23 C. AppraisalRefers to the assessment of evidence by systematically reviewing its relevance, validity and results to specific situations.Chambers, R. (1998). Clinical effectiveness made easy: first thoughts on clinical governance. Oxford, Radcliffe Medical Press.When you search Medline, the references that you retrieve have been published in recognised medical journals, some of which will have been peer reviewed. The peer review process means that the articles have been assessed by an expert in the field. This should help to prevent poor or inaccurate research being published. However, this does not mean that the research is always accurate or valid. Not all research is good research.One of the key messages of evidence based medicine is: "Don't believe everything you read."
24 Why is it important Critical appraisal is important because it: ensures a comprehensive assessment of the whole paperallows you to identify the strengths and weaknesses of a piece of researchdevelops an improved understanding of the research methodology used to conduct the researchallows you to relate the published research to your local situationenables you to identify any bias in the researchfacilitates the implementation of effective interventions in your clinical practice
25 Process of critical appraisal The process of critical appraisal can be very time consuming. It requires you to carefully read the whole article, especially the research methodology and statistical analysis - not just the "easy" bits like the introduction, results and conclusion sections!When reading an article you need to consider the following:Who has written the article? Are they a recognised author. Are they affiliated to a recognised institution?Why? What are the aims and objectives?How? Has the right research methodology been used?When? Is it recent or seminal research?Where? Has it been published in a recognised journal? Is it a peer reviewed journal?Do the results seem valid?Does the statistical evidence seem valid?Is there any obvious bias or conflict of interests?Do the conclusions stack up?
26 READER Relevance Is the study relevant to answer my Question? EducationDoes it challenge my knowledge?ApplicabilityDoes it apply to my situation?DiscriminationWhat is the scientific quality of the paper?EvaluationWhat is my evaluation based on above?ReactionHow can I use the information?
27 Three questions of critical appraisal: VIA Is the study Valid?Discrimination & EvaluationIs it Important?Relevance & EducationIs it Applicable to my patient?Applicability & Reaction
28 Question 1: Is the study valid? Type of study – strength of evidenceIs the study methodology appropriate to answer the research question?Was the study done properly?
29 Levels of evidenceWhat type of study would give the best evidence for each type of question?Level 1a: Systematic reviews; Level 1b: Individual RCTs with narrow confidence intervalLevel 2a & b: Cohort studies; Level 2c: Outcomes researchLevel 3a & b: Case-control studiesLevel 4: Case series & poor quality cohort /case control studies)Level 5: Expert opinion
30 Was the study done properly? SampleRepresentative and appropriateCase-control:Are cases and controls comparableCohort:Was patients followed long enoughWas loss to follow-up not too much?Randomised Controlled Trial:Double-blindWas randomisation done properlySystemic Review:Are all primary studies of high quality eg randomised controlled trials?Were results consistentIs the process explicit?Is synthesis accurate?
31 Are findings important? Impact/PrognosisP-valueConfidence intervalOutcome over timeAetiologyRelative riskOdds ratioSignificanceDiagnosis/evaluate testsCompare pre- and post-test probabilitySensitivitySpecificityPredictive valueTreatment/harmNumbers needed to treat/harmAbsolute risk reductionDiagnosis: 45 man 6% chance (pre-test probability) of having 75% stenosis of coronary arteries. With symptoms of chest pain on exertion, relieved after 10 min, with ST segment depression 2.2mm. His chance is now 90% (post-test probability). Is this significant?Prognosis: With smoking you have a risk to die is 2 x: RR= 1,89 (95% CI=1,65-2,13)3x higher in middle age (45-65) and 2x higher in old age (65-85)Therapy: Hypertension ( ): Death Stroke/MI: CER: 13% ;EER:1,4% ; NNT: 3Hypertension: (90-109): Death/Stroke/MI: CER: 5,5%; EER: 4,7%; NNT: 128Risk of Gastric Ulcers: Short term NSAID=3,6% Long term=6,8% NNT=
32 Is it applicable? Is your setting comparable to that of the study? Will the application of the evidence have a positive impact on your patients?What are your patients preferences?Would it be affordable in your setting?What alternatives are available in your setting?
33 Integration into practice Is your patient different from those in studyHow much effect do you expect in your patientsAre there alternativesWat does the patient think?
34 Other sources of evidence WHO CHOICE (Choosing interventions that are cost-effective)WHO initiative developed in 1998Reports the costs and effects of a wide range of health interventions in the 14 epidemiological sub-regions34
35 Ten best health buysVaccination of children against major childhood illnesses including measles, polio, tetanus, whooping cough, and diphtheriaMonitor children’s health to prevent or, if necessary, treat childhood pneumonia, diarrhoea, and malariaTax tobacco products to increase consumers’ costs by at least one-third to curb smoking and reduce the prevalence of cardiovascular disease, cancer, and respiratory disease.Attack the spread of HIV through a coordinated approach that includes:promoting 100 percent condom use among populations at high risktreating other sexually transmitted infectionsproviding antiretroviral medications, especially for pregnant womenoffering voluntary HIV counselling and testing.5. Give children and pregnant women essential nutrients including vitamin A, iron and iodine to prevent maternal anaemia, infant deaths, and long-term health problems
36 Provide insecticide-treated bed nets in malaria- endemic areas to drastically reduce malaria Enforce traffic regulations and install speed bumps at dangerous intersections to reduce traffic-related injuriesTreat TB patients with short-course chemotherapy to cure infected people and prevent new infectionsTeach mothers and train birth attendants to keep newborns warm and clean to reduce illness and deathPromote use of aspirin and other inexpensive drugs to treat and prevent heart attack and stroke