Page 64 - Htain Manual
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The probability ‘p’ mentioned here is varied until the individual is indifferent between
the two alternatives. This indifference probability, p, is the utility value for health state A in
the utility values between death (0) and full health (1).
Figure 3: Standard Gamble for a chronic health state preferred to a temporary health state
and death respectively (from left to right)
Time Trade-Off (TTO)
In this method also, the individual is asked to decide between two alternatives:
• Choice 1: Being in health state ‘A’ for ‘t’ years
• Choice 2: Being in full health for a period of ‘X’ years (where X<t ) followed by death
Time ‘X’ is varied until the individual is indifferent to the choice between the two
alternatives, at which point the preference value for health state A is given by X/t in the value
between death and full health, i.e., 0 and 1 respectively.
Figure 4: Time trade-off for a chronic health state preferred to death and for a temporary
health state (from left to right)
EQ5D
The EuroQoL Group, a consortium of investigators in Western Europe, developed a
system with five attributes (previously six): mobility, self-care, usual activity, pain/discomfort,
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