Transcript Dietary patterns in the ALSPAC cohort: Cluster analysis

Andrew Smith
Dietary patterns in the ALSPAC
cohort: Cluster analysis
EUCCONET International Workshop
18th October 2011
Andrew Smith
Dietary patterns in
the ALSPAC cohort:
Cluster analysis
Pauline Emmett
P. K. Newby
Kate Northstone
World Cancer Research Fund
Dietary patterns
• Examine diet as a whole
• Start with many variables
(e.g. FFQ, diet diary)
• Express as a small number of
variables
Image: Paul / FreeDigitalPhotos.net
Principal components analysis (PCA)
• Examine diet as a whole
• Start with many variables
(e.g. FFQ, diet diary)
• Use correlations between foods
• Express as a small number of
components
Image: Paul / FreeDigitalPhotos.net
Cluster analysis
• Examine diet as a whole
• Start with many variables
(e.g. FFQ, diet diary)
• Use similarities between people
• Express as a small number of
clusters
Image: Paul / FreeDigitalPhotos.net
Dietary patterns studies in ALSPAC
Source
PCA
Mothers’ FFQ
Northstone and Emmett, 2008a
Partners’ FFQ
Northstone and Emmett, 2010
FFQ age 3
North, Emmett et al. 2000
FFQ age 4½
Northstone, Emmett et al. 2005
FFQ age 7
Northstone, Emmett et al. 2005
FFQ age 9
Northstone and Emmett, 2008b
Diet diary age 10 in submission
FFQs age 13
in submission
Cluster
Smith et al. 2011
Case study: PCA of FFQ age 7
Junk
Traditional
Northstone and Emmett, 2005
Image: Suat Eman, winnond / FreeDigitalPhotos.net
Health conscious
Dietary patterns studies in ALSPAC
Source
PCA
Mothers’ FFQ
Northstone and Emmett, 2008a
Partners’ FFQ
Northstone and Emmett, 2010
FFQ age 3
North, Emmett et al. 2000
FFQ age 4½
Northstone, Emmett et al. 2005
FFQ age 7
Northstone, Emmett et al. 2005
FFQ age 9
Northstone and Emmett, 2008b
Diet diary age 10 in submission
FFQs age 13
in submission
Cluster
Smith et al. 2011
Cluster analysis
• k-means is most
widely-used method
• Must avoid pitfalls
– Standardization
– Algorithm
– Reliability
Image: Boaz Yiftach / FreeDigitalPhotos.net
Dietary patterns studies in ALSPAC
Source
PCA
Mothers’ FFQ
Northstone and Emmett, 2008a
Partners’ FFQ
Northstone and Emmett, 2010
FFQ age 3
North, Emmett et al. 2000
FFQ age 4½
Northstone, Emmett et al. 2005
FFQ age 7
Northstone, Emmett et al. 2005
FFQ age 9
Northstone and Emmett, 2008b
Diet diary age 10 in submission
FFQs age 13
in submission
Cluster
Smith et al. 2011
Case study: cluster analysis of FFQ age 7
• FFQ administered to ALSPAC children at 81
months of age
• Input variables are the same as PCA
(Northstone, Emmett et al. 2005)
• 8,279 children
• 3 clusters
•
Smith et al. 2011
Case study: cluster analysis of FFQ age 7
Processed 4177
children
White bread
Processed meat
Fizzy drinks
Ice cream
Plantbased
Brown/wholemeal bread Pasta
Fruit and vegetables
Rice
Vegetarian foods
Cereals
2065
children
Traditional 2037
British
children
Meat
Potatoes
Crisps
Chips
Squash
Biscuits and sweets
Full-fat milk
Similarities with PCA
Cluster analysis of diet diary data
• 7473 children aged 10
• Advantages
– Similar 3-cluster solution
(Processed, Plant-based, Traditional British)
– Good separation between clusters
• Disadvantages
– Not robust to under-reporting
– PCA shows better associations with fat mass
Dietary patterns studies in ALSPAC
Source
PCA
Mothers’ FFQ
Northstone and Emmett, 2008a
Partners’ FFQ
Northstone and Emmett, 2010
FFQ age 3
North, Emmett et al. 2000
FFQ age 4½
Northstone, Emmett et al. 2005
FFQ age 7
Northstone, Emmett et al. 2005
FFQ age 9
Northstone and Emmett, 2008b
Diet diary age 10 in submission
FFQs age 13
in submission
Cluster
Smith et al. 2011
Dietary patterns studies in ALSPAC
Source
PCA
Mothers’ FFQ
Northstone and Emmett, 2008a. Br J Nutr.
99 p.1099-106
Partners’ FFQ
Northstone and Emmett, 2010. EJCN 64
p.978-86
FFQ age 3
North, Emmett and the ALSPAC Study
Team, 2000. EJCN 54 p.73-80
FFQ age 7
Northstone, Emmett and the ALSPAC
Study team, 2005. EJCN 59 p.751-60
FFQ age 9
Northstone and Emmett, 2008b. Br J Nutr
100 p.1069-76
Diet diary age 10
in submission
FFQs age 13
in submission
Cluster
Smith, Emmett,
Newby, Northstone
2011. EJCN 65
p.1102-9