Methods, metrics and
meta-analysis
Alan Dangour
Leverhulme Centre for Integrative Research
in Agriculture and Health
Agriculture Health
Nutrition
Toxicants
Disease
Labour
Resources
Income
Household
National
Environment
Pollution
Sustainabi...
What do we know so far?
Not much for sure!
Agriculture Nutrition
No
thanks!
Mmmm,
interesting...
Evidence to-date?
• Systematic review of evidence linking agricultural
interventions with nutrition outcomes in children
•...
What are we doing now?
Running fast
(Bruegel the Elder, 1563)
Agricultural
production
Health
consequences
Food
consumption
Processing
Climate change
& carbon
emissions
Breeding &
varie...
Cross-sectoral work
• Are there nutrition/health benefits associated
with agricultural strategies to reduce GHG
emissions?...
Conceptual framework
• 30% drop in animal source food production
required to meet 2030 UK GHG target
• Diet / health modelling
– saturated fat ...
On-going work
• 151 current/planned relevant studies (in 2012)
• 46 different funders BMGF, CIDA, USAID, IDRC, DFID
• Rese...
Clear gaps
• Whole research chain i.e. from ag to nutrition
• Cost-effectiveness of interventions
• Population “sub”-group...
What do we need?
Methods
• Study design, study design, study design
• Some (but not all) agricultural innovations are
amenable to trials
– ...
Intervention vs.
observation
(Lawler, Lancet 2004)
Metrics
• Direct pathways
– how likely are impacts on stunting?
– dietary intake/diversity, micronutrient status
• Indirec...
Meta-analysis
• Requires multiple studies with
– similar design
– similar intervention
– similar outcome variables
• How d...
• Combined 234 meta-analyses; 1973 trials
• Characteristic: double blind or not
• Outcomes: mortality, other objective,
su...
Double-blinding
(Savovic, Arch Intern Med 2012)
Final words
• Robust evidence needed to tackle global health,
environmental and nutrition problems
• Unprecedented enablin...
Alan Dangour, LCIRAH  "Methods, metrics and meta-analysis"
Alan Dangour, LCIRAH  "Methods, metrics and meta-analysis"
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Alan Dangour, LCIRAH "Methods, metrics and meta-analysis"

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Alan Dangour, LCIRAH "Methods, metrics and meta-analysis"

  1. 1. Methods, metrics and meta-analysis Alan Dangour Leverhulme Centre for Integrative Research in Agriculture and Health
  2. 2. Agriculture Health Nutrition Toxicants Disease Labour Resources Income Household National Environment Pollution Sustainability (Dangour et al. Proc Nut Soc 2012)
  3. 3. What do we know so far?
  4. 4. Not much for sure! Agriculture Nutrition No thanks! Mmmm, interesting...
  5. 5. 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)
  6. 6. What are we doing now?
  7. 7. Running fast (Bruegel the Elder, 1563)
  8. 8. Agricultural production Health consequences Food consumption Processing 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
  9. 9. 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)
  10. 10. Conceptual framework
  11. 11. • 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
  12. 12. 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
  13. 13. 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
  14. 14. What do we need?
  15. 15. 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
  16. 16. Intervention vs. observation (Lawler, Lancet 2004)
  17. 17. 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
  18. 18. 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)
  19. 19. • Combined 234 meta-analyses; 1973 trials • Characteristic: double blind or not • Outcomes: mortality, other objective, subjective (Savovic, Arch Intern Med 2012)
  20. 20. Double-blinding (Savovic, Arch Intern Med 2012)
  21. 21. 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

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