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Assessment of Harm based on our best available evidences

Assessment of Harm based on our best available evidences. The EBM workshop A.A.Haghdoost, MD; PhD of Epidemiology Ahaghdoost@kmu.ac.ir. Why should we assess Harm. To choose the best treatment strategy To address to public questions and mass media

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Assessment of Harm based on our best available evidences

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  1. Assessment of Harm based on our best available evidences The EBM workshop A.A.Haghdoost, MD; PhD of Epidemiology Ahaghdoost@kmu.ac.ir

  2. Why should we assess Harm • To choose the best treatment strategy • To address to public questions and mass media • “Do oral contraceptives cause breast cancer?” • “Do calcium antagonists increase the risk of death or cancer?”

  3. Main steps • Systematic search • Check the validity of findings • Evaluate the importance of findings • Assess if the results are applicable to our setting

  4. Concerns • Are the results of published harm/aetiology study valid? • People listen to mass media much more than expert

  5. Main question? • Were there clearly defined groups of patients, similar in all important ways other than exposure to the treatment or other cause • Clinical trials • Cohorts • Case-controls • Case reports • phocomelia in children born to women who took thalidomide • Continued in next page

  6. Main question?

  7. Main question? • 2. Were treatments/exposures and clinical outcomes measured in the same ways in both groups? (was the assessment of outcomes either objective or blinded to exposure?) • More attention to positive group • Hawthorn effect • Continued in next page

  8. Main question? • 3. Was the follow-up of the study patients sufficiently long (for the outcome to occur and complete)? • Long enough to present the adverse effect • Long follow up usually increases the number of censured records • Continued in next page

  9. Main question? • 4. Do the results of the harm study fulfill some of the diagnostic tests for causation? • · Is it clear that the exposure preceded the onset of the outcome? • · Is there a dose–response gradient? • · Is there any positive evidence from a “dechallenge– rechallenge” study? • · Is the association consistent from study to study? • · Does the association make biological sense?

  10. Are the valid results of the harm study important? • What is the magnitude and precision of the association between the exposure and outcome? • OR, RR • NNH (Number Needed for Harm) • PAF (Population attributable Fraction) • Cost-benefits

  11. Can be applied on our setting • Is our patient so different from those included in the study that its results don’t apply? • What is our patient’s risk of the adverse event? What is our patient’s potential benefit from the therapy? • What are our patient’s preferences, concerns and expectations from this treatment? • What alternative treatments are available?

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