This lecture includes these contents: How to read a systematic review, the fast tool, a systematic review, selective criticism of evidence, meta analysis plot, pros and cons of systematic reviews,. Invite you to consult this lecture. | How to read a Systematic Review: The FAST tool Paul Glasziou Centre for Evidence Based Medicine University of Oxford Find Appraise Synthesise Transferability Are RCTs always needed for treatment questions? Some immediate & dramatic effects don’t need RCTs* Example: Child with nasal foreign body Dislodged with Parent Kiss method Case series of success 15/19 Botma J Laryngol Otol 2000 * Glasziou, Chalmers, Rawlins, McCulloch BMJ 2007 What do you do? For an acutely ill patient, you do a search You find several studies: some show significant results but many others don’t Forest Plot/Blobbogram: of these 17 studies Which is the smallest study? Which is the largest study? How many are statistically significant? Which studies are “large enough”? Of these 17 studies: of streptokinase for MI How large should the study be? What sample size is needed? For disease X the usual mortality rate is 0% What sample size is needed to detect a reduction in mortality? 100 1,000 100,000 1,000,000 Sample Size: Café Rule 1 The 50:50 Rule (proportions) 50 events are needed in the control group: (For an 80% chance of finding a 50% reduction) Glasziou P, Doll H. Was the study big enough? Two cafe rules. Evid Based Med. 2006;11(3):69-70. What sample size is needed? There is usually a 12% mortality rate You think your treatment will lower mortality by 50% What sample size is needed? What sample size is needed? There is usually a 12% mortality rate You think your treatment will lower mortality by 50% What sample size is needed? 12% means 12/100 or 24/200 or 48/400 and 50 per 417 Control + Treatment Groups = 834 in total Systematic Review or meta-analysis? A Systematic Review is a review of a clearly formulated question that uses systematic and explicit methods to identify, select and critically appraise relevant research, and to collect and analyse data from the studies that are included in the review. Statistical methods (meta-analysis) may | How to read a Systematic Review: The FAST tool Paul Glasziou Centre for Evidence Based Medicine University of Oxford Find Appraise Synthesise Transferability Are RCTs always needed for treatment questions? Some immediate & dramatic effects don’t need RCTs* Example: Child with nasal foreign body Dislodged with Parent Kiss method Case series of success 15/19 Botma J Laryngol Otol 2000 * Glasziou, Chalmers, Rawlins, McCulloch BMJ 2007 What do you do? For an acutely ill patient, you do a search You find several studies: some show significant results but many others don’t Forest Plot/Blobbogram: of these 17 studies Which is the smallest study? Which is the largest study? How many are statistically significant? Which studies are “large enough”? Of these 17 studies: of streptokinase for MI How large should the study be? What sample size is needed? For disease X the usual mortality rate is 0% What sample size is needed to detect a reduction in mortality?
