Critical appraisal

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Critical appraisal

  1. 1. Critical Appraisalof Medical Research Susan Fowler, MLIS 314-362-8092 fowler@wustl.eduPhoto: http://www.pantherkut.com/2009/05/27/cat-thoughts/
  2. 2. Agenda• Study Design• PICO(T)• Types of Questions• FRISBE• Clinical Importance• 3 Therapy Examples• Resources Photo: http://catscientists.tumblr.com/post/19458666129 Susan Fowler, MLIS Washington University in St. Louis
  3. 3. Photo: http://kuln.es/c5cwgSusan Fowler, MLIS Washington University in St. Louis
  4. 4. Basic Study DesignsExperimental Observational• Investigator • Investigator observes manipulates a variable outcome of naturally and examines effect on occurring difference in a an outcome variable• Designs • Designs – randomized controlled – Cohort study trial – Case control study – Controlled clinical trial – Case series study Systematic Review Workshop ©HSLS – University of Pittsburgh
  5. 5. Study Designs Definedmeta-analysis: a quantitative approach in which individual study findings addressing a common problem are statistically integrated and analyzed to determine the effectiveness of interventions.systematic review: a process by which a body of literature is reviewed and assessed using systematic methods which are intended to reduce bias in the review process and improve understandability. A controlled clinical trial in which the study groups are created through randomization.randomized controlled trial: an experiment in which investigators randomly allocate participants into (eg treatment and control) groups to receive or not to receive one or more interventions that are being compared.controlled clinical trial: any study which compares two groups by virtue of different therapies or exposures.cohort study: an observational study in which a cohort is followed over time.case-control studies: retrospective research design that compares individuals with a specific condition to those without it.case report: a detailed report of the symptoms, signs, diagnosis, treatment, and follow-up of an individual patient.case series: a report on a series of patients with an outcome or condition of interest. Susan Fowler, MLIS Washington University in St. Louis 2012
  6. 6. PICO (T) • Patient or problem - How would I describe a group of patients similar to mine? • Intervention - Which main intervention, prognostic factor, or exposure am I considering? • Comparison (if appropriate)- What is the main alternative to compare with the intervention? • Outcome - What can I hope to accomplish, measure, improve or affect? • Type of Study – Based on my question, what type of study will provide the best answer? Susan Fowler, MLIS Washington University in St. Louis 2012
  7. 7. Types of QuestionsType of Question Ideal Type of StudyTherapy RCTPrevention RCT > Cohort > Case ControlDiagnosis Prospective, blind controlled comparison to gold standardPrognosis Cohort > Case Control > Case Series/Case ReportEtiology/Harm RCT > Cohort > Case Control Susan Fowler, MLIS Washington University in St. Louis 2012
  8. 8. *FRISBE•Follow Up•Randomization•Intention to Treat•Similar Baseline•Blinding•Equal Treatment*Mnemonic tool created by Connie Schardt, AHIP Susan Fowler, MLIS Washington University in St. Louis 2012
  9. 9. Follow Up – Were all patients who entered the trial properly accounted for and attributed at its conclusion? Randomization - Was the allocation (assignment) of patients to treatment randomized? Was the allocation concealed? Intention-to-Treat Analysis - Were patients analyzed in the groups to which they were randomized? Were all randomized patient data analyzed? Similar Baseline Characteristics of Patients - Were groups similar at the start of the trial? Blinding - Were patients, health workers, and study personnel "blind" to treatment? Equal Treatment - Aside from the experimental intervention, were the groups treated equally?Photo: http://www.glassofwin.com/2010/06/03/cats-of-win-three-years/Susan Fowler, MLIS Washington University in St. Louis
  10. 10. ClinicalImportance
  11. 11. EER (Experimental Event Rate): The proportion of patients in the experimentaltreatment group who are observed to experience the outcome of interest.CER (Control Event Rate): The proportion of patients in the control groupobserved to experience the outcome of interest.ARR (Absolute Risk Reduction): The absolute arithmetic difference in rates of badoutcomes between experimental and control participants in a trial. (Also referred toas risk difference).RRR (Relative Risk Reduction): The proportional reduction in rates of badoutcomes between experimental and control participants in a trial.NNT (Number Needed to Treat): The number of patients who need to be treatedwith the specified intervention to prevent one bad outcome or to produce one goodoutcome over the period of time specified in the study. Susan Fowler, MLIS Washington University in St. Louis 2012
  12. 12. Outcome Outcome Present Absent Treated a= b= EER Exposed a a+b Control/not c= d= CER exposed c c+d RRR ARR NNT CER EER (CER-EER) CER-EER 1 CER ARRSusan Fowler, MLIS Washington University in St. Louis2012
  13. 13. Susan Fowler, MLIS Washington University in St. Louis2012
  14. 14. Library Resources Evidence at Becker (How To): http://beckerguides.wustl.edu/ebm Duke University Evidence-Based Practice: http://guides.mclibrary.duke.edu/eb m Centre for Evidence Based Medicine: http://www.cebm.net/index.aspx? o=1023Susan Fowler, MLISfowler@wustl.edu314-362-8092 Clip Art from http://www.wpclipart.com/ Susan Fowler, MLIS Washington University in St. Louis
  15. 15. Q u e s t I o n sPhoto by Juniors Bildarchiv ?Susan Fowler, MLIS Washington University in St. Louis2012

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