2. CRITICAL APPARAISAL OF A PAPER ON THERAPY 421 CORSE EVIDENCE BASED MEDICINE (EBM)

3. WHAT IS EBM ?

4. ” قل هاتوا برهانكم إن كنتم صادقين “

5. Clinical expertise Research evidence Patient preferences

6. EBM: THE PRACTICE

7. THE STEPS IN THE EBM THE PATIENT1. Start with the patient – a clinical problem/question arises out of the care of the patient. THE QUESTION2. Construct a well built clinical question derived from the case. THE SOURCE3. Select the appropriate resource(s) and conduct a search. THE EVALUATION4. Appraise that evidence for its validity and applicability

8. THE STEPS IN THE EBM (CONT….) THE PATIENT THE PATIENT SELF EVALUATION SELF EVALUATION 5. Return to the patient, integrate that evidence with clinical expertise, patient preference, and apply it in practice. 6. Evaluate your performance with the process

9. A WELLBUILT CLINICAL QUESTION PATIENT / PROBLEM INTERVENTION COMPARISON OUTCOME P I C O

10. TYPES OF STUDY

11. EXPERIMENTAL EXPERIMENTAL NONEXPERIMENTAL NONEXPERIMENTAL

12. THERAPUETIC STUDY THERAPUETIC STUDY WHAT STUDY DESIGN ? WHAT STUDY DESIGN ? CLINICAL TRIAL CLINICAL TRIAL

19. What is critical apparaisal ?

20. WHAT DO WE LOOK FOR? VALIDITY VALIDITY IMPORTANCE IMPORTANCE APPLICATION APPLICATION

21. A. Are the results Valid? Valid 1.Was the assignment of patients to treatment Randomized?Randomized 2.Was the randomisation list concealed ? 3. Were all patients who entered the trial properly accounted for and attributed at its conclusion? (FOLLWO UP) A distinction: Withdrawal: A participant in a clinical trial discontinues prescribed treatment programe (deviates from protocol). Dropout: A failure to measure the outcome of interest for a trial participant at this and subsequent visits. (80% response is accepted (less than that, should be justified, why?)

22. 4.Were patients analyzed in the groups to which they were randomized ? Intention to Treat Analysis? Intention to Treat Analysis?Intention to Treat AnalysisIntention to Treat Analysis The basic ITT principle is that participants in the trials should be analysed in the groups to which they were randomized, regardless of whether they received or adhered to the allocated intervention adhered

23. 4. Were patients, their clinicians and study personnel 'blind' to treatment? 5. Were the groups similar at the start of the trial? Baseline prognostic factors (demographics, co-morbidity, disease severity, other known confounders) balanced? If different, were these adjusted for?prognostic factors 6. Aside from the experimental intervention, were the groups treated equally? Co-interventionCo-intervention? Contamination? Compliance?

24. B. WHAT ARE THE RESULTS?

25. What are the results? 1. How large is the treatment effect? Absolute risk reduction? Relative risk reduction?Absolute risk reductionRelative risk reduction NUMBER NEED TO TREAT? NUMBER NEED TO HARM? 2. How precise is the estimate of the treatment effect? Confidence intervals?Confidence intervals

26. TOTAL OUTCOME EVENT NOYES a+bba EXPERIMNTAL GROUP C+ddc CONTROL GROUP

27. B.WHAT ARE THE RESULTS? Experimental group: a b a + b Control group: c d c + d Experimental event rate = risk of outcome event in experimental group = EER = a/(a+b) Control event rate = risk of outcome event in control group = CER = c/(c+d) Absolute risk reduction (ARR) = CER – EER Number needed to treat (NNT) = 1/ARR = 1/(CER - EER)

28. Totalplacebo Nitrofuran tion Outcome (symptomatic cure or improvement at day 7) 311120+VE 19145-VE 5025 Total ARR= CER-EER= 11/25 - 20/25 =0.44-0.8 = 0.36 NNT= 1/ARR= 1/0.36 =2.78 ===3

29. Will the results help me in patient care? 1.Can the results be applied to my patients? Patients similar for demographics, severity, co-morbidity and otherco-morbidity prognostic factors? Compelling reason why they should not be applied? 2. Were all clinically relevant outcomes considered? Are surrogate endpoints valid?surrogate endpoints 3. Are the benefits worth the harms and costs? NNT for different outcomes?NNT

30. According the secondary end point of long term of Continuous abstinence (weeks 9-26) Stopped chewingDidn’t stopTotal varenicline95118213 placebo73145218 Total168263431 Experimental event rate EER = 95/213 = 0.446 Control event rate CER = 73/218 = 0.335 Absolute risk reduction ARR = EER – CER Absolute risk reduction ARR = 0.446  0.335 = 0.111 Number need to treat NNT = 1/ARR Number need to treat NNT = 1/0.111 Number need to treat NNT = 9.01 ≈ 9

31. Results We need to treat 9 tobacco users for 12 weeks with varenicline and follow them up for another 14 weeks to make 1 more patient stop chewing tobacco compared to placebo. We need to treat 9 tobacco users for 12 weeks with varenicline and follow them up for another 14 weeks to make 1 more patient stop chewing tobacco compared to placebo.