alan dangour, lcirah "methods, metrics and meta-analysis"
DESCRIPTION
Science Forum 2013 (www.scienceforum13.org) Breakout Session 1 - UNDER-NUTRITION Alan Dangour presentationsTRANSCRIPT
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Methods, metrics and
meta-analysis
Alan Dangour
Leverhulme Centre for Integrative Research
in Agriculture and Health
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Agriculture Health
Nutrition
Toxicants
Disease
Labour
Resources
IncomeHousehold
National
EnvironmentPollution
Sustainability(Dangour et al. Proc Nut Soc 2012)
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What do we know so far?
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Not much for sure!
Agriculture Nutrition
No
thanks!
Mmmm,
interesting...
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Evidence to-date?• Systematic review of evidence linking agricultural
interventions with nutrition outcomes in children
• 23 studies included (15 on home gardens; <5 RCTs)
(Masset et al. BMJ 2012)
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What are we doing now?
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Running fast
(Bruegel the Elder, 1563)
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Agricultural
production
Health
consequences
Food
consumptionProcessing
Climate change
& carbon
emissions
Breeding &
varietal
development
Water
availability
Land
use
Husbandry
techniques
Seeds, veterinary
& agrochemical
inputs
Labour
Soils
Bio-fortification
Advertising
&
promotion
Post-harvest
processing
Industrial
scale &
concentration
Transportation
Product
fortification
Investment & speculation
Labour
Sanitary &
phytosanitary standards
Trade & regulation
Education
Price
Access
Income
Cooking
processes
Diet composition
Waste
Consumer preferences
Hygiene
Culture
Stunting
Development
potential
Obesity
Cardiovascular
disease
Nutritional
deficiencies
Infections
Diabetes
Wasting
Cancer
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Cross-sectoral work
• Are there nutrition/health benefits associated
with agricultural strategies to reduce GHG
emissions?
• Linked environment, diet, health
(Friel, Dangour, Garnett et al. Lancet 2009)
• Even messier example included economy
(Lock, Smith, Dangour et al. Lancet 2010)
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Conceptual framework
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• 30% drop in animal source food production
required to meet 2030 UK GHG target
• Diet / health modelling
– saturated fat intake → ischaemic heart disease
• 30% reduction in saturated fat consumption
– 17% drop in premature deaths (~18,000 deaths)
• “Significant co-benefit to health”
• Economy: “Winners and losers”
GHG and health – results
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On-going work
• 151 current/planned relevant studies (in 2012)
• 46 different funders BMGF, CIDA, USAID, IDRC, DFID
• Research most often directed at improving the
production and availability of nutritious foods
– Biofortification & other crop improvements
– Indigenous/local foods/agrobiodiversity
– Value chains for nutritious foods
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Clear gaps
• Whole research chain i.e. from ag to nutrition
• Cost-effectiveness of interventions
• Population “sub”-groups (urban/male)
• Indirect effects on nutrition
• Effects of agriculture policy on nutrition
• Political economy of agriculture-for-nutrition policies
• Nutrition-related non-communicable diseases
• Development of methods and metrics
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What do we need?
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Methods
• Study design, study design, study design
• Some (but not all) agricultural innovations are amenable to trials
– biofortified crops, mobile messages, home gardens
• Evidence from other disciplines
– regression discontinuity analysis, counterfactual decomposition, qual/quant mixed methods
• Learning across disciplines
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Intervention vs.
observation
(Lawler, Lancet 2004)
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Metrics
• Direct pathways– how likely are impacts on stunting?
– dietary intake/diversity, micronutrient status
• Indirect pathways– income / livelihoods
– expenditure on schooling, WASH, health care...
• Policy outcomes– evaluation methods
– measurable outcomes
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Meta-analysis
• Requires multiple studies with
– similar design
– similar intervention
– similar outcome variables
• How do we deal with “clinical heterogeneity”?
• How do we include other study designs?
• We must share raw data
– Dangour et al. 2013 (n=5 trials; n=>4500 children)
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• Combined 234 meta-analyses; 1973 trials
• Characteristic: double blind or not
• Outcomes: mortality, other objective,
subjective
(Savovic, Arch Intern Med 2012)
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Double-blinding
(Savovic, Arch Intern Med 2012)
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Final words
• Robust evidence needed to tackle global health,
environmental and nutrition problems
• Unprecedented enabling policy environment
But we urgently need:
• Carefully asked research questions
• Carefully designed research studies
• New partnerships forged across disciplines
• Innovative thinking and problem solving