SCC 2012 Positively Uncertain (Amanda Burls)


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  • 01/08/12
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  • SCC 2012 Positively Uncertain (Amanda Burls)

    1. 1. Positively uncertainBritish Science AssociationScience Communication Conference 2012Dr Amanda BurlsDirector of Postgraduate Programmes in Evidence-Based Health CareUniversity of Oxford
    2. 2. In a traffic accident which would you prefer?A. A team trained and “Stay and Play” equipped for advanced trauma life support to stabilise you in the field? orB. A team trained and equipped only for basic life support to take you as quickly as possible to the nearest A&E? “Scoop and Run”
    3. 3. The aim of teaching“… to give an in-depth understanding ofthe evidence-based approach to practice,and the skills to translate these into theeffective care of patients and informedhealth-care policies.”
    4. 4. First task: learn to recognise uncertainty
    5. 5. In a traffic accident which would you prefer?A. ATLS? “Stay and Play” OrB. BLS? “Scoop and Run”
    6. 6. Systematic review of ATLS vs BLSLiberman et al J Trauma 2000 49(4):584-59915 papers reported mortalityDirection of research findings by quality of study:- Quality ATLS BLS Fair 1 5 Good 1 1 Excellent 1 64 to 1 in favour of BLS!Combined –Relative risk of death with ATLS: 2.92
    7. 7. Doctors by disposition and trainingwant to act decisively…
    8. 8. Lots of examples where we got it wrong Lack of research Failure to systematically review studies Failure to use evidence
    9. 9. “To be uncertain isuncomfortable, to becertain is ridiculous” Chinese Proverb
    10. 10. “Education is the path from cockyignorance to miserable uncertainty.” Mark Twain
    11. 11. Objectives of ProgrammeWork comfortably in situations of uncertainty and make sound judgements in the absence of definitive evidence. unpredictable situations and deal with complex issues systematically and creatively
    12. 12. You don’t haveto be supermanto deal withuncertaintieseffectively!
    13. 13. UncertaintyIndividual ignorance Unknown Not questioned Not researched Not searched Researched but not Not found written up Poor indexing Written up but no up-to- Poor searching skills date systematic review Behind paywall Systematic review but… Couldn’t make sense of Primary studies biased what found Results contradictory Results inconclusive because lack of power
    14. 14. Would you want oxygen if you werehaving a heart attack?
    15. 15. Oxygen therapy for acute myocardial infarction.Cochrane Database Sys Rev 2010;6:CD007160“The evidence is suggestive of harmbut lacks power so this could be dueto chance. Current evidence neithersupports nor clearly refutes the routineuse of oxygen in patients with acutemyocardial infarction”.
    16. 16. Assuming the review waswell-conducted, would youcontinue to give oxygen routinelyto patients with a heart attack?
    17. 17. The right answer?“Should oxygen be given in myocardial infarction?On the basis of physiological reasons and no trialevidence of harm: YES.” Atar D (editorial) BMJ 2010;340:c3287 (16June)“In the meantime, those who adhere to the advice to´above all, do no harm´ would be best advised to avoidoxygen in patients with acute myocardial infarction,unless the patient has demonstrably low oxygen levels,and then only deliver sufficient to avoid hyperoxia.” Weston C (editorial) The Cochrane Library 2010 (16 June)
    18. 18. Involve yourpatients aspartners
    19. 19. “The only certainty is that nothing is certain.” Pliny the Elder
    20. 20. Probability“When one admits that nothing iscertain one must, I think, alsoadmit that some things are muchmore nearly certain than others.” Bertrand Russell
    21. 21. Teaching philosophy “Tell me and Ill forget; show me and I may remember; involve me and Ill understand.”
    22. 22. 1. This problem is rarely caused by a bacterial infection.2. Our patients are often called by the x-ray department the morning after.3. Sometimes we have nothing to do and the patient dies.4. This inflammation typically causes recurrent episodes of wheezing.5. Breathlessness is frequently present at night.6. These symptoms are usually associated with widespread airflow limitation.7. The airflow obstruction of asthma is generally reversible.8. These symptoms are nonspecific, making asthma sometimes difficult to distinguish from other respiratory diseases.9. This normally happens in otherwise strong boys.10. The probable cause is Neisseria meningitidis.
    23. 23. 2012 (Range and Medians) 0 10 20 30 40 50 60 70 80 90 100 Rarely Often Sometimes Typically Frequently Usually Generally Normally Sometimes Probably Oxford International Programme in Evidence-Based Health Care. Clinical Epidemiology
    24. 24. Uncertainty due to bias
    25. 25. Teaching I won’t rea lly believe you “Tell me and Ill forget; show me and I may remember; involve me and Ill understand.”
    26. 26. Teaching AND communicating with patients I won’t rea lly believe you “Tell me and Ill forget; show me and I may remember; involve me and Ill understand.”
    27. 27. Unconscious measurement bias
    28. 28. Be honest with patients about uncertainties 50
    29. 29. Uncertainty – a real example Childhood leukaemia in Pembroke Road between 1985-1994 Cases observed = 5 Cases expected = 1 P < 0.0025 Relative Risk = 5.6
    30. 30. Is this likely to be a cluster? Yes No Parents Me Chief Executive Director of Public Chronicle and Echo Health Dispatches
    31. 31. Age-standardised rates of childhood leukaemia in Northamptonshire by District 1969-1988 and 1989-94, as available in 1995 Number of Children Age-standardised rates of leukaemia in children under District with leukaemia 15 per million children under 15 1969-88 1989-94 1969-1988 1989-1994Corby 12 2 44.3 31.4Daventry 10 3 38.3 39.5East Nhants 16 5 60.0 62.3Kettering 8 3 26.1 32.6Northampton 26 9 38.2 38.1South Nhants 19 5 64.0 58.6Wellingborough 15 2 52.4 24.1Northamptonshire 106 29 44.8 39.9England 7431 N/A 37.8 N/A
    32. 32. It can’t be a coincidence
    33. 33. The Texas sharp-shooter error
    34. 34. No excessleukaemia!
    35. 35. The biggest danger in any clusterinvestigation is “generating” anapparently significant cluster whencases really occurred by chance
    36. 36. “Mobile phone mast causing brain cancer!”Is there an excessnumber of cerebralcancers beingcaused by thetelephone mast?
    37. 37.
    38. 38. h
    39. 39. Advanced EBHC MSc students During the “Swine Flu” epidemic pregnant women were advised to get vaccinated against the flu Was the governments immunisation policy an over-reaction or a sensible public health policy? Nearly everyone had a firmly held belief
    40. 40. What assumptions are you making? Vaccination risky? How risky would it have to be before it is not worth having? Threshold number to vaccinate to prevent one death? Weighing up sore arms against death or a bout of influenza?
    41. 41. Summary – teach people To recognise uncertainties Intuition & pathological reasoning are unreliable Good intentions can do more harm than good Stick to where there is evidence of net benefit, or Do them in way in which they can be evaluated Find, appraise and integrate evidence efficiently If “certain” be explicit about assumptions Involve patients Don’t be afraid to say “I don’t know”