Gordon Guyatt
Clarity Research Group
McMaster University
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what is the problem?
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whose values and preferences?
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how can we find out about values and
preferences?
applying best estimates of V and P
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almost all decisions/recommendations involve
tradeoffs
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benefits versus harms, burden, costs
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antithrombotic therapy
 thrombosis reduction vs bleeding, burden, costs
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tradeoffs require V and P judgments
 value reducing MI, stroke, DVT vs bleed and burden
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guideline panel members
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health care providers
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policy makers
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subjects of the guideline
 patients
 general public
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systematic review of patient V and P
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use guideline panel members
 act as proxies for their patients’ V and P
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patients on panel
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collect own values and preferences data
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comprehensive search
 48 studies
 16 a fib, 10 stroke or MI, 5 VTE, 17 burden
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higher disutility on stroke than gastrointestinal
bleed and much greater disutility on stroke
than on treatment burden
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example of the relative value of health states:
 a reasonable trade-off between nonfatal stroke and
bleeds is a ratio of disutility of 2.1 to 3.1
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systematic review results require
interpretation
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how should guideline panel proceed?
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systematic V and P rating exercise
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ACCP
 consider systematic review
 make ratings for typical patients
 rate scenarios, time frame of one year
 Full Health
 Maximum
Feeling thermometer:
Venous limb gangrene
 Mean
 Minimum
 Dead
13
Physical
Symptoms
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Mental
Symptoms
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Pain
Recovery
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Further
Risk
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Your child suddenly becomes unresponsive
Your child is unable to move one arm and one leg
Your child cannot speak to you
Your child is irritable and upset
You find it difficult to console your child
Family and friends find the diagnosis difficult to accept
Your child has a headache for a number of days
Your child’s stay in hospital is prolonged
Your child recovers some function, including speech and
movement slowly over weeks to months
Your child complains of tiredness for months
Your child needs help to attend normal school
Your child has multiple hospital visits for physiotherapy
and rehabilitation
You must alter your hopes and dreams for your child’s
future
You are told your child is not at risk of further strokes,
You find your child’s ongoing limitations very hard to
accept
14
 Full Health
 Maximum
Feeling thermometer:
Major stroke in a child
 Mean
 Minimum
 Dead
15
Symptoms
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Diagnostic
tests and
treatment
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Recovery
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You feel nauseated and unwell for two days, and then suddenly you vomit blood
and feel faint.
You are taken by ambulance to a busy emergency department.
An intravenous catheter is placed and a catheter is placed through your nose
into your stomach to help drain the blood
You receive blood transfusions to replace the blood you lost
You are admitted to hospital
A doctor puts a tube down your throat into your stomach to see where you are
bleeding from and to provide treatment
You receive sedation by intravenous to ease the discomfort of the test
You do not require an operation to stop the bleeding
You must stop taking your blood thinner; stopping the blood thinner puts you at
risk of developing a new blood clot.
You stay in the hospital for a few days
You feel much better at the end of your hospital stay
You need to take pills for the next six month to prevent further bleeding
After that, you are back to normal
About 2 weeks after your bleeding you restart your blood thinning therapy –
you worry every day about more bleeding for the first month after restarting
After that, your worry gradually decreases
16
 Full Health
 Maximum
Feeling thermometer:
Gastrointestinal bleed
 Mean
 Minimum
 Dead
17
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myocardial infarction = pulmonary
embolus = venous thrombosis =
gastrointestinal bleed
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stroke = 3 bleeds (and thus three of any
other major event)
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strong recommendation
 confident more good than harm
 almost all informed patient make same choice
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tight balance
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uncertainty about typical V and P
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uncertainty about variability in V and P
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V and P highly variable
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Strong recommendation for warfarin
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often advocated
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may be useful in issues overlooked
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no guarantee reflects typical V and P
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establish that everyone agrees with evidence
summary
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clarify values and preferences
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Review evidence about patient V and P
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value and preference judgments ubiquitous
panels MUST make judgments explicit
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quantitation desirable
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values those who bear consequences
weak recommendation more likely
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 close trade-off
 uncertainty in typical V and P
 highly variable V and P
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systematic review of V and P – routine
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still need panel input
 study results require interpretation
 results likely incomplete
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structured elicitation of panel V and P
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patients on panel – questionable
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expert panel shared decision-making