A comparison of methods to assess changes in dietary patterns from pregnancy to 4 years post-partum obtained using principal components analysis
Open Access
- 1 May 2008
- journal article
- research article
- Published by Cambridge University Press (CUP) in British Journal of Nutrition
- Vol. 99 (5), 1099-1106
- https://doi.org/10.1017/s0007114507842802
Abstract
Few studies have examined the longitudinal nature of dietary patterns obtained using principal components analysis (PCA); the methods used are inconsistent. This paper investigates the methodologies used to assess stability and changes in such patterns. Pregnant women recorded frequency of consumption of various food items as part of regular self-completed questionnaires in the Avon Longitudinal Study of Parents and Children. This was repeated when their children were 4 years of age; 8953 women provided data at both times. Dietary patterns were identified using PCA and component scores were calculated at each time point. Additional ‘applied’ scores were created at 4 years using the loadings obtained from the PCA on the pregnancy data. Correlations were similar for each component across the time points, though slightly larger using the applied method. The applied scores were considerably lower on average than those obtained from separate PCA at 4 years. Women's scores decreased on ‘health conscious’ and ‘confectionery’ components while ‘processed’ and ‘vegetarian’ scores both increased over the 4-year period. In contrast, applied scores were systematically lower for all components. When split into quintiles, weighted κ was slightly higher between pregnancy and applied 4-year scores compared to the separate scores. In this cohort it was felt that the ‘applied’ method to obtain scores at the second time point was inappropriate, primarily due to the differences in FFQ between the two time points. We recommend that future studies using such ‘applied’ scores compare them with cross-sectional scores and consider the implications of any differences.Keywords
This publication has 24 references indexed in Scilit:
- Dietary patterns in pregnancy and associations with socio-demographic and lifestyle factorsEuropean Journal of Clinical Nutrition, 2007
- Stability of dietary patterns in young women over a 2-year periodEuropean Journal of Clinical Nutrition, 2007
- Dietary Patterns and Changes in Body Weight in WomenObesity, 2006
- Dietary patterns and associated lifestyles in preconception, pregnancy and postpartumEuropean Journal of Clinical Nutrition, 2005
- ALSPAC–The Avon Longitudinal Study of Parents and ChildrenPaediatric and Perinatal Epidemiology, 2001
- Diet during pregnancy in a population of pregnant women in South West EnglandEuropean Journal of Clinical Nutrition, 1998
- Longitudinal dietary changes between 1984–5 and 1991–2 in British adults: associations with socio-demographic, lifestyle and health factorsBritish Journal of Nutrition, 1997
- STATISTICAL METHODS FOR ASSESSING AGREEMENT BETWEEN TWO METHODS OF CLINICAL MEASUREMENTThe Lancet, 1986
- Weighted kappa: Nominal scale agreement provision for scaled disagreement or partial credit.Psychological Bulletin, 1968
- The Scree Test For The Number Of FactorsMultivariate Behavioral Research, 1966