- mobility (no problems in walking about, some problems in walking about,
confined to bed), - self-care (no problems with self-care, some problems washing or dressing self,
unable to wash or dress self), - usual activities (no problems with performing usual activities (e.g., work, study,
housework), some problems with performing usual activities, unable to perform
usual activities), - pain and discomfort (no pain or discomfort, moderate pain or discomfort,
extreme pain or discomfort), - anxiety and depression (not anxious or depressed, moderately anxious or
depressed, extremely anxious or depressed).
Combing the levels within each particular dimension yields a total of 243 possi-
ble health states whose accompanying preference-based scores are obtained using
mathematical functions and econometric models. The scores (also termed utility
weights or utilities) associated with each health state available from the EQ-5D are
represented on a scale where 0 represents death and 1 represents full health. QALYs
are calculated by multiplying the time spent in a certain health state by the utility
weight of that health state. For instance, if a patient with a particular illness is
expected to live for the next 5 years, and in those 5 years the patient will experience
a quality of life valued at 50 % of full health, then the number of QALYs in the
absence of treatment is (50.5)¼2.5 QALYs. If, with the treatment, patient’s life
expectancy increases to 7 years at the quality of life valued at 90 %, then the number
of QALYs gained from treatment is (0.97)¼6.3. Hence, the benefit from the
treatment sums up to (6.32.5)¼3.8 QALYs gained.
The valuation of changes in health-related quality of life (i.e., utilities) are based
either on public preferences or patients’preferences, elicited using a choice-based
method. The three main choice-based methods are the visual analog scale (VAS),
time trade-off (TTO), and standard gamble (SG). Multiple utility sets have been
calculated and published, as reported by Lamers et al. ( 2006 ) for the Dutch context
and Szende et al. ( 2007 ) for the UK context.
2.2 The Measure of Costs
In principle, economic evaluations use two types of costing procedures:
macrocosting and microcosting. The main difference between the two costing
approaches is the level of aggregation at which appropriate costs are measured
and valued. In the macrocosting approach, the analyst identifies and measures
integrated products and services (for instance, aggregated costs of inpatient days).
Microcosting, on the other hand, refers to an inventory and costing out of every
input used in the process of treatment of a particular patient, such as personnel
hours, occupied office space, travel time and cost, etc. Microcosting is particularly
useful for estimating the cost of new technologies or new community-based
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