# Dr Carl Thompson, University of York Lecture 1 Recognising and capturing clinical uncertainty.

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Dr Carl Thompson, University of York Lecture 1 Recognising and capturing clinical uncertainty

Dr Carl Thompson, University of York Foreground and background knowledge Background knowledge foreground knowledge Expertise and decision making

Dr Carl Thompson, University of York clarification Clinical uncertainty Clinical uncertainty Clinical judgement Clinical judgement Clinical decision making Clinical decision making Evidence based decision making Evidence based decision making

Dr Carl Thompson, University of York Clinical uncertainty Not certainly knowing or known Not certainly knowing or known Sources Sources Defining a disease Defining a disease Making a diagnosis Making a diagnosis Selecting an intervention Selecting an intervention Observing outcomes Observing outcomes Assessing patient preferences Assessing patient preferences Combing information in a decision Combing information in a decision

Dr Carl Thompson, University of York Quantifying Uncertainty True state of the patient cannot be directly observed True state of the patient cannot be directly observed Clinician must use imperfect external cues Clinician must use imperfect external cues Probability as a language for expressing uncertainty Probability as a language for expressing uncertainty

Dr Carl Thompson, University of York Probability Fundamentals Strength of belief Strength of belief A number between 0 and1 that expresses an opinion about the likelihood of an event A number between 0 and1 that expresses an opinion about the likelihood of an event Probability of an event that is certain to occur is 1 Probability of an event that is certain to occur is 1 Probability of an event that is certain to NOT occur is 0 Probability of an event that is certain to NOT occur is 0

Dr Carl Thompson, University of York Types of probability TermdefinitionFormularange Probability The chance of an event P0-1 Proportion relative frequency of a state P0-1 Prevalence The proportion of a group with a specific disease P0-1 Percentage Probability expressed as a frequency per 100 P x 100 0-100 Frequency Probability expressed per sample (1 per 1000) P 0 – denomi nator Odds Ratio of the probability of an event to its complement P(/1-P) 0- infinity Incidence rate Occurrence of new disease cases P/t 0- infinity Incidence proportion The proportion of people who develop a new disease or event during a period of time P0-1 Risk The probability that an individual develops a new disease during or event a specified period of time P0-1

Dr Carl Thompson, University of York Components of Probability Estimates Personal experience Personal experience Published experience - evidence Published experience - evidence Attributes of the patient Attributes of the patient

Dr Carl Thompson, University of York Clinical decision and judgement Clinical judgement Clinical judgement Assessment of alternatives Assessment of alternatives Clinical decision Clinical decision Choosing between alternatives Choosing between alternatives (Dowie 1988)

Dr Carl Thompson, University of York The decisions clinicians make. Diagnosis and test ordering (Dx) Diagnosis and test ordering (Dx) Treatment (Rx) Treatment (Rx) Targeting Targeting Timing Timing referral referral Communicating (risks and benefit info) Communicating (risks and benefit info) Seeking more information Seeking more information S.D.O. (service delivery and organisation) S.D.O. (service delivery and organisation)

Dr Carl Thompson, University of York Clinical uncertainty – the good news Aeschylus – ‘hope comes from the lack of certainty of fate’ Aeschylus – ‘hope comes from the lack of certainty of fate’ Complete certainty = lack of hope Complete certainty = lack of hope Examination results predicted life success (100% accurately) Examination results predicted life success (100% accurately) Learning at age 12 that you possess the Alzheimer’s gene Learning at age 12 that you possess the Alzheimer’s gene Adaptation to Huntington’s and HIV status Adaptation to Huntington’s and HIV status

Dr Carl Thompson, University of York Asking questions Background questions: Background questions: General knowledge about a disorder General knowledge about a disorder A root (who, what, when, how, and why) a verb A root (who, what, when, how, and why) a verb A disorder or aspect of a disorder A disorder or aspect of a disorder E.g. ‘what causes angina?’ E.g. ‘what causes angina?’

Dr Carl Thompson, University of York Foreground questions P.I.C.O. Specific knowledge about management of people with a disorder Specific knowledge about management of people with a disorder Population: the people who are on the receiving end of your judgement and choices Population: the people who are on the receiving end of your judgement and choices Intervention: that which you are thinking of doing to (with?) them Intervention: that which you are thinking of doing to (with?) them Counter intervention: the other choices – nb. sometimes not in a question when no choice Counter intervention: the other choices – nb. sometimes not in a question when no choice Outcome: what do you want see happen (or not happen) as a result of your choice? Outcome: what do you want see happen (or not happen) as a result of your choice?

Dr Carl Thompson, University of York Population - Can Include: Disease or condition Disease or condition Sex, age, race, socio-economic setting Sex, age, race, socio-economic setting Stage of disease, care setting Stage of disease, care setting

Dr Carl Thompson, University of York Interventions - Can Include: General or specific interventions General or specific interventions treatment options or specific drug, risk factors or specific cause treatment options or specific drug, risk factors or specific cause Level of intervention Level of intervention Frequency/dosage Frequency/dosage Stage of intervention Stage of intervention prevention, secondary prevention, early, advanced prevention, secondary prevention, early, advanced Delivery of intervention Delivery of intervention setting, professional group, self-medication setting, professional group, self-medication

Dr Carl Thompson, University of York Comparisons With The Intervention - Can Include: Standard practice Standard practice Gold standard intervention Gold standard intervention Placebo Placebo Other specific comparisons Other specific comparisons

Dr Carl Thompson, University of York Outcomes - Can Include: Clinical Outcomes Clinical Outcomes mortality, reduction of symptoms, adverse effects mortality, reduction of symptoms, adverse effects Provider-oriented Outcomes Provider-oriented Outcomes cost-effectiveness, benefits to service cost-effectiveness, benefits to service Patient-oriented Outcomes Patient-oriented Outcomes QoL, satisfaction, acceptance QoL, satisfaction, acceptance

Dr Carl Thompson, University of York Why bother with PICO? Helps focus scarce learning time on relevant evidence for patient need Helps focus scarce learning time on relevant evidence for patient need Helps focus scarce learning time on evidence that addressed your knowledge needs Helps focus scarce learning time on evidence that addressed your knowledge needs Suggests high yield search strategies Suggests high yield search strategies Suggest the form useful answers might take Suggest the form useful answers might take Aid referrals by clearly communicating needs Aid referrals by clearly communicating needs As a basis for teaching others (clarity in communication) As a basis for teaching others (clarity in communication) Leads to answers  increases your motivation Leads to answers  increases your motivation

Dr Carl Thompson, University of York Some examples Is sucrose a safe and effective analgesic during painful procedures in newborns? Do prenatal and postnatal home visits by nurses have long term effects on maternal and child outcomes? Do transparent polyurethane dressings reduce dislodgement, phlebitis, and “tissuing” of peripheral IV catheters compared to gauze? Is exposure to parental tobacco smoke associated with an increased risk of asthma in school age children?

Dr Carl Thompson, University of York Your go! populationinterventionCounter intervention Outcome

Dr Carl Thompson, University of York Intro to a Search Strategy: Start with a clear answerable question Start with a clear answerable question Break the question down into concepts Break the question down into concepts Search each concept separately Search each concept separately (use indexing terms, other indexing features, textwords] (use indexing terms, other indexing features, textwords] Combine terms Combine terms Limit results Limit results

Dr Carl Thompson, University of York Searching For Individual Concepts: Indexing terms (thesaurus terms, subject headings) Indexing terms (thesaurus terms, subject headings) eg. MeSH eg. MeSH mapping mapping Textwords Textwords synonyms synonyms alternative spellings and word endings alternative spellings and word endings truncation (usually \$ or *) eg. manag\$ truncation (usually \$ or *) eg. manag\$ proximity operators [usually adj# or near#] eg. home adj3 help proximity operators [usually adj# or near#] eg. home adj3 help exact phrase [usually “ # ”] eg. “clinical governance” exact phrase [usually “ # ”] eg. “clinical governance”

Dr Carl Thompson, University of York Combining concepts AND - Creates a smaller set; both concepts must be present. In this case the result set is the records which contain both the smoking and counselling concepts. AND - Creates a smaller set; both concepts must be present. In this case the result set is the records which contain both the smoking and counselling concepts. Result set Smoking Counselling

Dr Carl Thompson, University of York Combining concepts OR - Creates a larger set; any or all concepts must be present. Used to link similar concepts. In this case the result set is the records which contain both the psychotherapy and counselling concepts (all the blue area) OR - Creates a larger set; any or all concepts must be present. Used to link similar concepts. In this case the result set is the records which contain both the psychotherapy and counselling concepts (all the blue area) Psychotherapy Counselling

Dr Carl Thompson, University of York Combining concepts NOT - Excludes a concept. Used to remove specific concepts. In this case the result set is the records which contain tobacco but not those which also contain snuff (yellow hatched area). Use with care because it can have unexpected results. NOT - Excludes a concept. Used to remove specific concepts. In this case the result set is the records which contain tobacco but not those which also contain snuff (yellow hatched area). Use with care because it can have unexpected results. Snuff Tobacco

Dr Carl Thompson, University of York Example search, using MEDLINE subject headings #1 substance use disorders/ #2 exp substance dependence/ #3 drug adj addiction #4 or/1-3 #5 exp child/ #6 teenager? or adolescent? or young adj people #7 or/5-6 #8 exp health promotion/ #9 prevent? adj (campaign? or program? or activit?) #10 or/8-9 #11 4 and 7 and 10

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