TY - JOUR
T1 - Long-term behavioural consequences of infant feeding
T2 - The limits of observational studies
AU - Kramer, Michael S.
AU - Fombonne, Eric
AU - Matush, Lidia
AU - Bogdanovich, Natalia
AU - Dahhou, Mourad
AU - Platt, Robert W.
PY - 2011/11
Y1 - 2011/11
N2 - Observational (non-experimental) studies of the association between infant feeding and subsequent child or adult behaviour are prone to residual confounding by subtle differences in psychological attributes and interactional styles of mothers who breast feed vs. those who formula-feed. We followed up 13 889 6.5-year-old Belarusian children who participated in a large cluster-randomised trial of a breast-feeding promotion intervention. Behaviour was evaluated using the Strengths and Difficulties Questionnaire (SDQ), completed independently by the children's parents and teachers. We compared the results of experimental (intention-to-treat, ITT) and observational analyses (based on feeding actually received), both adjusted for clustering. Observational analyses were additionally adjusted for geographical region, urban vs. rural residence, child's sex, age at follow-up, birthweight, and maternal and paternal education. No differences between the randomised experimental vs. control groups were observed in ITT analyses. In contrast, small but statistically significant associations with weaning prior to 3 months were observed for parent and teacher SDQ scores on total difficulties, conduct problems and hyperactivity, even after multivariable adjustment. The absence of associations based on ITT analyses, in contrast with the significant associations based on observed breast-feeding duration, strongly suggests that the latter are biased by residual confounding.
AB - Observational (non-experimental) studies of the association between infant feeding and subsequent child or adult behaviour are prone to residual confounding by subtle differences in psychological attributes and interactional styles of mothers who breast feed vs. those who formula-feed. We followed up 13 889 6.5-year-old Belarusian children who participated in a large cluster-randomised trial of a breast-feeding promotion intervention. Behaviour was evaluated using the Strengths and Difficulties Questionnaire (SDQ), completed independently by the children's parents and teachers. We compared the results of experimental (intention-to-treat, ITT) and observational analyses (based on feeding actually received), both adjusted for clustering. Observational analyses were additionally adjusted for geographical region, urban vs. rural residence, child's sex, age at follow-up, birthweight, and maternal and paternal education. No differences between the randomised experimental vs. control groups were observed in ITT analyses. In contrast, small but statistically significant associations with weaning prior to 3 months were observed for parent and teacher SDQ scores on total difficulties, conduct problems and hyperactivity, even after multivariable adjustment. The absence of associations based on ITT analyses, in contrast with the significant associations based on observed breast-feeding duration, strongly suggests that the latter are biased by residual confounding.
KW - RCT
KW - breast feeding
KW - child behaviour
KW - weaning
UR - http://www.scopus.com/inward/record.url?scp=80054087234&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=80054087234&partnerID=8YFLogxK
U2 - 10.1111/j.1365-3016.2011.01211.x
DO - 10.1111/j.1365-3016.2011.01211.x
M3 - Article
C2 - 21980939
AN - SCOPUS:80054087234
SN - 0269-5022
VL - 25
SP - 500
EP - 506
JO - Paediatric and Perinatal Epidemiology
JF - Paediatric and Perinatal Epidemiology
IS - 6
ER -