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EVIDENCE BASED MEDICINE: THERAPEUTIC APPRAISAL

EVIDENCE BASED MEDICINE: THERAPEUTIC APPRAISAL. COMMUNITY RESEARCH PROGRAM 2. DO YOU KNOW THAT WHAT YOU HAD READ IN THE COLLEGE COULD BE MISLEADING IN THE FUTURE? HOW CAN BE SURE THAT THE DISEASE YOU’LL BE DEAL WITH, ONLY COME IN PERSISTENT MANNER JUST LIKE THE REFFERENCES?

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EVIDENCE BASED MEDICINE: THERAPEUTIC APPRAISAL

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  1. EVIDENCE BASED MEDICINE:THERAPEUTIC APPRAISAL COMMUNITY RESEARCH PROGRAM 2

  2. DO YOU KNOW THAT WHAT YOU HAD READ IN THE COLLEGE COULD BE MISLEADING IN THE FUTURE? • HOW CAN BE SURE THAT THE DISEASE YOU’LL BE DEAL WITH, ONLY COME IN PERSISTENT MANNER JUST LIKE THE REFFERENCES? • DO YOU ALWAYS HAVE THE TIME TO FOLLOW THE MEDICAL SCIENCE ADVANCES?

  3. AS A DOCTOR WHOM WELL IN TOUCH WITH INTERNET SURF THE WEB GET THE (UNAPPRAISED) ARTICLES

  4. THE PROBLEM IS • DOES THE ARTICLE(S) VALID? • IF IT WAS VALID, DOES IT REALLY IMPORTANT?

  5. THERAPEUTIC EVIDENCE • “VALID” COMPONENTS • RANDOMIZED • RANDOMIZATION CONCEALED • STANDARDIZED SUBJECTS • SUFFICIENT FOLLOW UP • EACH GROUP ANALYZED • DOUBLE BLINDING • EQUAL TREATMENT BETWEEN GROUPS • “IMPORTANT” COMPONENTS • MAGNITUDE • PRECISION

  6. 1. WAS THE ASSIGNMENT OF PATIENTS TO TREATMENT RANDOMIZED? • WHY RANDOMIZED BECOME SO IMPORTANT? versus

  7. OBSERVATIONAL STUDY • CONFOUNDING PARTIALLY UNKNOWN • UNEVENLY DISTRIBUTION OF PROGNOSTIC FACTORS BETWEEN GROUPS • RANDOMIZATION • EQUAL DISTRIBUTION OF POTENTIAL CONFOUNDERS BETWEEN GROUPS THE RESULT IS DIFFERENT ! POST MENOPAUSAL POST MENOPAUSAL CAD NON CAD CAD NON CAD HRT NON HRT HRT GROUP SOME KNOWN RISK FACTOR matching CAD NON CAD NON HRT GROUP HRT NON HRT RANDOMIZED

  8. 2. WAS THE RANDOMIZATION CONCEALED • The clinicians don’t know which patient gonna be given which medication • IF IT WAS NOT WRITTEN EXPLICITLY, SEARCH FOR HINTS LIKE RANDOMIZATION BY PHONE OR SYSTEM FROM DISTANCE

  9. 3.WERE THE GROUPS SIMILAR AT THE START? • SIMILARITY IN ALL PROGNOSTICALLY IMPORTANT WAYS

  10. 4. WAS THE FOLLOW UP PATIENTS SUFFICIENTLY LONG AND COMPLETE? • PATIENTS DROP OUT BECAUSE OF ADVERSE OUTCOMES, THEIR ABSENCE FROM ANALYSIS WOULD LEAD TO AN OVER ESTIMATION OF THE EFFICACY OF TREATMENT • LOSS OF >20% COULD HAVE A BIG IMPACT ON RESULT. LUCKILY, JOURNALS SUCH AS EVIDENCE BASED MEDICINE AND ACP JORNAL CLUB WON’T PUBLISH TRIALS WITH <80% FOLLOW UP • HOW IF THE STATIN STUDY TO DECREASE THE RISK OF BECOMING STROKE ONLY STUDIED IN 1 WEEK OR 1 MONTH?

  11. 5. WERE ALL PATIENTS ANALYZED IN THE GROUPS TO WHICH THEY WERE RANDOMIZED • THE AIM OF THIS APPRAISAL IS TO MAINTAIN THE PATIENTS PERSISTENTLY IN THEIR GROUP • IF THEY CAN’T STEADILY STAY IN EACH GROUP, THEY MUST BE ANALYZED

  12. 5 STEPS ABOVE ARE THE MAJOR CRITERIA FOR VALIDITY OF A STUDY

  13. 6. WERE PATIENTS,CLINICIANS AND STUDY PERSONEL KEPT BLIND TO TREATMENT? CLINICIANS STUDY PERSONNEL PATIENTS DRUG A DRUG B DRUG A DRUG B PATIENTS W/DRUG A ANALYZING PATIENTS W/DRUG B

  14. 7. WERE GROUPS TREATED EQUALLY, APART FROM THE EXPERIMENTAL THERAPY? • NO CO INTERVENTION ON EACH GROUP

  15. THE LAST TWO STEPS ABOVE ARE THE MINOR CRITERIA FOR VALIDITY OF A STUDY. IF THE STUDY FAILS ANY OF THE 7 CRITERIAS DISCUSSED ABOVE, WE NEED TO DECIDE F THE FLAW IS SIGNIFICANT AND THREATENS THE VALIDITY OF A STUDY. IF THIS IS THE CASE, WE’LL NEED TO LOOK FOR ANOTHER STUDY. IF WE FIND THAT OUR ARTICLE SATISFIES ALL OF THE CRITERIA, WE CAN PROCEED TO CONSIDERATION OF ITS IMPORTANCE

  16. ARE THE VALID RESULT OF THIS STUDY IMPORTANT? • WHAT IS THE MAGNITUDE OF THE TREATMENT EFFECT? • HOW PRECISE IS THE ESTIMATE OF THE TREATMENT EFFECT?

  17. ... ANY QUESTION ?

  18. 1. WHAT IS THE MAGNITUDE OF THE TREATMENT EFFECT? • EER • CER • EER (EXPERIMENTAL EVENT RATE) • CER (CONTROL EVENT RATE) DISEASE+ SUM DISEASE - SUM THERAPY GROUPS THERAPY DISEASE- DISEASE+ PLACEBO SUM DISEASE - SUM PLACEBO GROUPS DISEASE-

  19. EXAMPLE • WITH THE THERAPY GIVEN 6,25% DISEASE HEALED • WITH THE THERAPY NOT GIVEN9% DISEASE HEALED • EER (EXPERIMENTAL EVENT RATE) • CER (CONTROL EVENT RATE) 75 6,25 % 80 5 91 100 9 % 9

  20. CROSS TAB Experimental event rate : B/(A + B) Control event rate : D/(C + D)

  21. NOW YOU CAN SEE THE DIFFERENCE • ANY SLIGHT DIFFERENCE, AS LONG AS IT IS DIFFERENT, WE MAY CALL IT (STATISTICALLY) SIGNIFICANT FROM EXAMPLE, THERE IS 2,75% DIFFERENCE OF THE DISEASE THAT HEALED IN PLACEBO GROUP COMPARED TO THERAPY GROUP

  22. WHAT ABOUT CLINICALLY IMPORTANCE? TWO WAYS TO SEE THE IMPORTANCE • RRR (RELATIVE RISK REDUCTION) • ARR (ABSOLUTE RISK REDUCTION) IF THE MEDICINE REDUCE THE RISK OF BEING HAS THE DISEASE

  23. AND IF THE MEDICINE INCREASE THE RISK? • RRR AND ARR CHANGE INTO RRI AND ARI

  24. NNT=1/ARR RRR = (CER-EER) CER ARR = CER-EER BEFORE WE INTERPRET THE ARR, WE MUST CONTINUE TO MEASURE THE NNT (NUMBER NEED TO TREAT), BECAUSE: 1.TO SEE HOW MANY PEOPLE MUST BE MEDICATED TO PREVENT THE DISEASE 2.LESS NNT, MEANS GOOD THERAPY (TO COMPARE WITH ANOTHER THERAPY) • DISADVANTAGES: • RRR DOESN’T REFLECT THE RISK OF THE EVENT WITHOUT THERAPY • RRR CANNOT DISCRIMINATE HUGE TREATMENT EFFECT FROM SMALL ONES

  25. WE BETTER STICK TO THE ARR. WHY?

  26. COULD THE MEDICATION DO HARM? • YES. AS EVERY MEDICATION HAS THE SIDE EFFECT • NNH=1/ARI

  27. FROM DIFFERENT STUDY, ABOUT THE DIFFERENT INTERVENTION TO REDUCE THE SAME DISEASE, WE CAN CHOOSE THE LESSER NNT THAT DO THE BEST. • PROBLEM IS, HOW IF THE NNT’S PRODUCED FROM DIFFERENT TIME?

  28. EXAMPLE WHICH STUDY WOULD BE THE BETTER ONE?

  29. FIRSTLY, TO COMPARE, WE NEED TO UNIFORM THE TIME • NNThypotethic Xhypotethic time= NNTobserved x observedtime • NNThypotethic= NNTobserved x(observedtime/hypotethic time) • TAKE STUDY 2 • NNT1,5=128 (5,5/1,5) =470

  30. 2. HOW PRECISE IS THIS ESTIMATE OF THE TREATMENT EFFECT? • NNT ARE ESTIMATES OF THE TRUTH • NNT MUST LIE IN SPECIFIED CI • EXAMPLE: NNT 72 WITH 95% CI OF 51 TO 1170:WE WOULD HAVE CONFIDENCE THAT THE TRUE NNT VALUE LIES FROM 51 TO 1170

  31. LET’S PRACTICE • Step 1: What question did the study ask? • Population/problem:… • Intervention:… • Comparison:… • Outcome:…

  32. Step 2: how well was the study done? (internal validity) • Recruitment- were the subject representative?

  33. Allocation-was the allocation randomized and concealed…?

  34. So that the groups were comparable at the start of the trial?

  35. Maintenance-did the groups have equal co-interventions…?

  36. Was there adequate follow up?

  37. Measurement-were the subjects and assessors kept ‘blind’ to which treatment was being received and/or were the measure objective?

  38. WHAT DO THE RESULTS MEAN?

  39. Conclusion • Internal validity… • Results…

  40. alhamdulillah

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