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timetradeoff

Time trade-off, commonly abbreviated as TTO, is a method used in health economics to elicit the value or utility of a specific health state for use in cost-utility analysis and quality-adjusted life year (QALY) calculations. It is designed to capture an individual's preference for living a given health state for a certain period versus living in perfect health for a shorter period, thereby translating subjective well-being into a numeric utility between 0 and 1 (with 1 representing perfect health and 0 representing death).

In a typical TTO task, a respondent is asked to choose between two options: living a specified

Applications of TTO include informing reimbursement and coverage decisions, modeling QALYs, and supporting health technology assessments.

number
of
years
in
the
current
health
state,
or
living
a
shorter
number
of
years
in
full
health.
The
duration
in
full
health
is
varied
until
the
respondent
is
indifferent
between
the
two
options.
The
resulting
utility
is
calculated
as
the
duration
in
full
health
divided
by
the
total
duration
of
the
comparison
scenario
(for
example,
9
years
in
full
health
vs
10
years
in
the
current
health
state
yields
a
utility
of
0.9).
Some
variations
allow
for
states
considered
worse
than
death,
using
methods
such
as
lead-time
TTO
to
assign
negative
utilities.
Limitations
include
cognitive
burden
on
respondents,
framing
effects,
cultural
and
individual
differences
in
time
preferences,
and
assumptions
of
linearity
of
utility
over
time.
Variants
and
refinements
continue
to
address
these
issues,
aiming
to
improve
consistency
and
comparability
across
studies.