What is Evidence-Based Medicine? Mohammad Reza Honarvar MD.MPH Some slides are adopted from Payam Kabiri, MD. PhD.

طبق آمار منتشر شده در آمريكا سالانه بطور متوسط 16000 نفر به علت ایدز 32000 نفر بعلت سرطان سینه 23000نفر بعلت تصادفات و33000 تا 98000نفربعلت خطای پزشکان جان خودراازدست می دهند

به طور متوسط براي پزشكان به ازاي هر مريض بستري 5 سوال و به ازاي هر 3 مريض سرپايي 2 سوال پيش ميآيد كه پاسخ آن را نمي دانند. درمواردي كه اين سوالات پاسخ داده شد ه اند، در % 30 مواردتصميم گيري باليني و در % 10 موارد پيامد بيماري تغييرمي كند.

Volume of new information a major barrier 5,000? per day 1,360 per day 55 per day

For General Physicians to keep current: Read 19 new articles per day which appear in medical journals 19 x 2 hrs (Critical Appraisal) = 38 hrs per day Davidoff F et al. (1995) EBM; A new journal to help doctors identify the information they need. BMJ 310:1085-86.

از زمان توليد اطلاعات تا ورود آن به حيطه كار پزشكان سال ها طول مي كشد از زمان توليد اطلاعات تا ورود آن به حيطه كار پزشكان سال ها طول مي كشد. يك درمان موثر به طور متوسط 10 سال بعد از اينكه كارآيي آن ثابت شد وارد كتاب مي شود. گاه توصيه آن تا 10 سال بعد از ثابت شدن بي اثر يا مضر بودن آن ادامه مي يابد. اطلاعات پزشكي از درجه اعتباربسيار متفاوتي برخوردارند و پزشكان توانايي كافي براي نقد اطلاعات و جدا كردن اطلاعات معتبر از غير معتبر را ندارند. در حاليكه حتي در ژورنال هاي خيلي سطح بالا هم تعداد اندكي از مقالاتي كه چاپ مي شوند هم كيفيت بالا و هم اهميت باليني دارند.

Knowledge Gap Amount of Information is rising Knowledge Gap Time to meet information needs decreasing The Knowledge Gap

Can’t I trust the editors? Percent of articles meeting quality criteria NEJM 12.6% Ann Int Med 7.6% JAMA 7.2% Lancet 6.2% BMJ 4.4% Arch Int Med 2.4%

Medical Publishing Annually: 20,000 journals 17,000 new books MEDLINE: 17 Million references 400,000 new entries yearly

Types of Medical articles Original Article Review Article Case Reports

Primary studies Experiments Clinical trials Surveys

Secondary studies Reviews (Overviews) Narrative reviews Systematic reviews & Meta-analyses Guidelines Decision analyses Economic analyses

Hierarchy of studies

EBM History G. Guyatt from McMaster University in 90s Sackett in 1995 defined EBM “Our clinical decision making should be based on the best scientific available evidence”

What is Evidence? Evidence is anything used to determine or demonstrate the truth of an assertion. Scientific evidence is evidence which serves to either support or counter a scientific theory or hypothesis. In scientific research evidence is accumulated through observations of phenomena occur in the natural world, or created as experiments in a laboratory

What is ‘level of evidence’? The extent to which one can be confident that an estimate of effect or association is correct (unbiased).

Levels of Evidence Level of Evidence Type of Study 1a 1b 2a 2b 3a 3b 4 Systematic reviews of randomized clinical trials (RCTs) 1b Individual RCTs 2a Systematic reviews of cohort studies 2b Individual cohort studies and low-quality RCTs 3a Systematic reviews of case-controlled studies 3b Individual case-controlled studies 4 Case series and poor-quality cohort and case-control studies 5 Expert opinion based on clinical experience Adapted from: Sackett DL et al. Evidence-Based Medicine: How to Practice and Teach EBM. 2nd ed. Churchill Livingstone; 2000.

What is Evidence-Based Medicine? “Evidence-based medicine is the integration of best research evidence with clinical expertise and patient values” - Sackett & Straus

EBM - What is it? Clinical Expertise Research Patient Preferences Evidence Patient Preferences

Integrate Findings With Clinical Expertise and Patient Needs Critical Appraisal Patient Clinical Decision Preferences Concerns Expectations Clinical Expertise Step 4: Integrate Findings With Clinical Expertise and Patient Needs According to Sackett et al., the fourth step in practicing evidence-based medicine requires the integration of the findings from the critical appraisal with clinical expertise and patient needs. Evidence-based medicine is the integration of clinical expertise, patient values, and the best evidence into the decision-making process for patient care. Clinical expertise refers to the clinician’s cumulated experience, education, and clinical skills. By patient values we mean the unique preferences, concerns, and expectations each patient brings to a clinical encounter which must be integrated into clinical decisions if they are to serve the patient. The best evidence is usually found in clinically-relevant research that has been conducted using sound methodology. The evidence, by itself, does not make a decision for you, but it can help support the patient care process. The full integration of these three components into clinical decisions enhances the opportunity for optimal clinical outcomes. Adapted from: Sackett DL et al. Evidence-Based Medicine: How to Practice and Teach EBM. 2nd ed. Churchill Livingstone; 2000.

EBM Steps Ask your clinical question Search your literature for answer Appraise the retrieved documents Apply your findings Evaluate the performance

EBM Method your patient questions best evidence the evidence Assess your patient Ask clinical questions Alternative to next slide Acquire the best evidence Appraise the evidence Apply evidence to patient care

What are the limitations of EBM? First, the need to develop new skills in searching and critical appraisal can be daunting, although (as we pointed out above) evidence-based care can still be applied if only the former has been mastered and directed toward pre-appraised resources

Second, busy clinicians have limited time to master and apply these new skills, and the resources required for instant access to evidence are often woefully inadequate in clinical settings. Finally, evidence that EBM “works” has been late and slow to come.

Was it clear enough !

اگرميل داشتيد اي ميل بزنيد honarvar@goums.ac.ir موفق باشيد