Preventing Childhood Obesity - Evidence Policy and Practice.pdf

Evidence framework for childhood obesity prevention
in this book and only some overview comments are
be made here.
In general, it is possible to generate quite long lists
of potential interventions to help prevent childhood
obesity, although some of the intervention areas, such
as improved parenting skills, are more readily identified
in generalities than in specific interventions.
However, adding effectiveness evidence to any more
than a few of them is very difficult because of the
absence of intervention studie. For the interventions
that have been studied, most concern primary school
children, most are in school settings, most are short
term, most are not sustainable, and most have shown
relatively modest effects on anthropometry (although
they were often able to show improvements in eating
and/or physical activity). The number of reviews in
the area is starting to outnumber the number of
studies. 9 – 29
As interventions move towards more whole - of -
community interventions, there is an increased complexity
in the study design, the interventions and the
evaluations, although some positive results are starting
to emerge from these studies, which is very
encouraging. 30 – 32 More sophisticated multi - level modeling
will be needed to tease out intervention effects
in these more complex interventions.
For policy - makers considering strategy options,
the distinction between effectiveness and cost –
effectiveness is critical. If a policy objective is to be
pursued with no limitation on spending, then effectiveness
(the beneficial effect of a strategy in practice)
is the primary consideration. But when cost limitations
apply (as they inevitably do), an evaluation of
cost – effectiveness is essential if rational decisions are
to be made. 33
A remarkable feature of the evaluations and systematic
reviews of interventions described above is that
they rarely mention the costs of the various programs
they examine, and make no estimates of cost –
effectiveness. For child obesity prevention, only one
study has explicitly examined the costs of an intervention
program, the US Planet Health Program. 34 Planet
Health ’ s estimated cost – effectiveness ratio gives a
value of $4305 per quality - adjusted life year gained,
which compares favorably with interventions such as
the treatment of hypertension, low - cholesterol - diet
therapies, some diabetes screening programs and
treatments, and adult exercise programs. 35
Creating a p ortfolio
of i nterventions
The evidence for obesity prevention covered thus far
has shown: a substantial burden to warrant action;
sufficient understanding of the determinants to know
what to target; a determination of the priority target
populations ( who ), the best settings to access ( where ),
and the most appropriate strategies to use ( how ), and;
a review of the literature about what has been shown
to work, or not work. The final challenge in the IOTF
framework (prior to actually implementing and evaluating
the work) is to create the “ portfolio ” of interventions
to be implemented. And what a challenge in
priority setting it is, because the aim of intervention
selection is:
to agree upon a balanced portfolio of specific,
promising interventions to reduce the burden of
obesity and improve health and quality of life
within the available capacity to do so.
“ Agreement ” infers a process with decision makers
coming to a joint understanding. “ Balanced portfolio ”
means a balance of content (both nutrition and physical
activity), settings (not all school - based), strategies
(policies, programs, communications), and target
groups (whole population, high risk). Interventions
need to be “ specific ” (not “promote healthy eating ”)
and “ promising ” rather than proven. The analogy of
choosing a balance of products (shares, property,
bonds) to create portfolio of financial investments has
been used by Hawe and Shiell 36 to conceptualize
appropriate investment in health. The best investments
are the safe, high - return ones (i.e,. high level of
evidence, high population impact) but, inevitably, the
choices come down to including some safe, lower -
return investments and some higher - risk (i.e., less
certainty), potentially higher - return investments
while excluding the high - risk, low - return ones. The
IOTF framework 1 applies this investment concept to
obesity prevention and presents a “ promise table ”,
which is a grid of certainty (strength of evidence)
versus return (population impact) into which
interventions can be placed according to their
credentials.
The other key concepts in the priority setting aim
are that the interventions reduce the “ burden of
obesity ” and “ improve health and quality of life ”.
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