No reduction in risk in childhood asthma/allergy symptoms found with longer breast-feeding
Article Outline
- Kramer MS, Matush L, Vanilovich I, Platt R, Bogdanovich N, Sevkovskaya Z, et al, for the Promotion of Breastfeeding Intervention Trial (PROBIT) Study Group. Effect of prolonged and exclusive breast feeding on risk of allergy and asthma: cluster-randomised trial. BMJ 2007;335:815-20
- Reference
- Copyright
Kramer MS, Matush L, Vanilovich I, Platt R, Bogdanovich N, Sevkovskaya Z, et al, for the Promotion of Breastfeeding Intervention Trial (PROBIT) Study Group. Effect of prolonged and exclusive breast feeding on risk of allergy and asthma: cluster-randomised trial. BMJ 2007;335:815-20
Question
Does exclusive and prolonged breast-feeding reduce the risk of childhood asthma and allergy by 6.5 years of age?
Design
Cluster-randomized trial.
Setting
31 Belarussian maternity hospitals and their affiliated polyclinics.
Participants
A total of 17,046 mother–infant pairs were enrolled, 13,889 (81.5%) of which were followed up at age 6.5 years.
Intervention
Breast-feeding promotion intervention modeled on the WHO/UNICEF baby-friendly hospital initiative.
Outcomes
International study of asthma and allergies in childhood (ISAAC) questionnaire and skin prick tests of 5 inhalant antigens.
Main Results
The intervention led to a large increase in exclusive breast-feeding at 3 months (44.3% vs 6.4%; P < .001) and a significantly higher prevalence of any breast-feeding at all ages up to and including 12 months. The experimental group exhibited no reduction in risk of allergic symptoms and diagnoses or positive skin prick tests. In fact, after exclusion of 6 sites (3 experimental and 3 control) with suspiciously high rates of positive skin prick tests, risks were increased significantly for 4 of the 5 antigens in the experimental group.
Conclusions
These findings do not support a protective effect of prolonged and exclusive breast-feeding on asthma or allergy.
Commentary
Could breast-feeding protect against asthma/allergy even years later? This cluster-randomized, controlled trial assessed whether a successful breast-feeding promotion was associated with reduced risk of asthma/allergy 6 years later. The trial overcame many challenges inherent in studying breast-feeding and health. The cluster design, with hospitals as the unit of randomization, allowed good estimation of effects within each group. The successful intervention increased the duration of total and exclusive breast-feeding. Assigning the mothers to intervention or usual care eliminated the confounding inherent in many observational studies of breast-feeding. Furthermore, feeding data were of high quality and collected prospectively. Finally, the study was adequately powered to find even a small effect. The study had some limitations, including a highly selected sample (those intending to breast-feed). In addition, the duration of breast-feeding in the 2 groups may have been too similar to produce differing outcomes. Most importantly, the true prevalence of asthma/allergy may not have been measured by either history of asthma symptoms or positive allergy skin tests for airborne allergens; the reported asthma prevalence was low compared with US rates. Furthermore, the use of skin prick tests as an outcome is problematic because of known low positive predictive value in the absence of specific supporting symptoms.1 This adequately powered, well-designed, breast-feeding promotion intervention study found no association between breast-feeding and decreased risk for allergy/asthma. Limitations notwithstanding, this study provides the best evidence to date.
Reference
PII: S0022-3476(07)01147-X
doi:10.1016/j.jpeds.2007.12.003
© 2008 Mosby, Inc. All rights reserved.
