Preventing Childhood Obesity - Evidence Policy and Practice.pdf

Economic evaluation of obesity interventions
Cost-of-illness study: A type of burden of disease
study that describes the relationship between
current disease incidence and/or prevalence
and the consequent resource implications, particularly
for the structure and utilization of health
services.
Direct costs: The monetary value of a resource provided
to deliver medical or social services as part
of the management of the disease.
Economic evaluation: A comparative analysis of the
costs and outcomes of an intervention measured
against a comparator.
Epidemiological modeling: Modelling is used to move
from a change in behaviour (such as an increase in
physical activity to a change in energy expenditure
to the desired outcome (e.g. BMI) using a mix of
evidence types and levels.
Incremental cost – effectiveness ratio (ICER): The ratio of
the difference in net costs between two alternatives
to the difference in net effectiveness between the
same two alternatives.
Indirect costs: The value of a decrease in an individual
’ s productivity as a result of the disease.
Indirect evidence: Information that strongly suggests
that the evidence exists (e.g. a high and continued
investment in food advertising is indirect evidence
that there is positive [but propriety] evidence that
food advertisement increases sales of those
products).
Opportunity cost: The value of the best alternative use
of a resource that is foregone as a result of its
current use.
Parallel evidence: Evidence of intervention effectiveness
for another public health issue using similar
strategies (e.g. the role of social marketing, regulation
or behavioral change initiatives in tobacco
control, sun exposure, speeding, etc.).
Threshold analysis: A decision aid used to assist
resource allocation decisions. A decision maker
may specify an acceptable level of investment or
return on an investment. This information is then
used to determine which combination of parameter
estimates could cause the threshold to be exceeded
or achieved.
Evaluating i nterventions to
p revent o besity
Irrespective of their views about the potential contribution
of COI and causal research, most economists
would agree that the fight against obesity requires a
“solutions-based” rather than a “problem-focused”
approach, and that it is the fourth plank of economics,
“ economic evaluation ”, which offers the potentially
most valuable contribution. High quality evaluations
of potential obesity interventions are required so that
policy-makers know “what works ” and what offers
“value for money ”.
A full economic evaluation of a selected intervention
is characterized by the incremental assessment of
both its costs and benefits measured against a comparator,
usually current practice. 18 This enables the
analyst to answer the essential policy question of
“ what difference the intervention is likely to make to
the disease burden and what is the net cost of doing
so ”. The change in costs is compared with the change
in outcomes and reported as an incremental cost –
effectiveness ratio ( ICER ). Typically, with obesity
interventions, the ICER will be reported as “ net cost
per kg of weight lost ”, “ net cost per BMI (body mass
index) unit saved ”, “ net cost per life - year gained ” or
“ net cost per quality - adjusted life - year saved ( QALY ).
To date, very few obesity interventions have been
subjected to rigorous economic evaluation. It has
primarily been treatment options involving either
surgical or pharmacological therapies that have been
economically evaluated. 1,19 These two publications
between them identified only one economic evaluation
of a preventive intervention 20 and seven of lifestyle
treatment interventions involving diet, exercise
or behaviour therapy. Furthermore, some of these
were not targeted exclusively at obese persons, but
at persons for whom obesity was a serious complication
or subsequent disease. In a recent discussion of
the literature, Cawley 21 listed four published cost –
20,22 – 24
effectiveness studies of anti-obesity interventions,
of which only one was a preventive measure.
Our own work in assessing the cost – effectiveness of
thirteen interventions targeting unhealthy weight gain
in children and adolescents as part of the Assessing
Cost – Effectiveness in Obesity ( ACE - Obesity ) project
in Australia 25 is, to our knowledge, the largest body of
work around the economic evaluation of obesity
interventions. The interventions were evaluated using
a consistent protocol to avoid methodological confounding.
Some individual interventions evaluations
have been published, and summarized results are
available ( www.health.vic.gov.au/healthpromotion/
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