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Breast Feeding And Asthma


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Breast Feeding And Asthma

  1. 1. Breast Feeding & Asthma :Should we promote breast feeding? It is not controversial that breast-feeding is the preferred method of infant nutrition because of its nutritional, immunological, and psychological benefits Effects on reducing early childhood wheezing, GI tract infections and atopic eczema (in early life) was demonstrated by several studies Effects on childhood asthma is controversial especially in mother who has asthma Friedman et al. JACI 2005;115:1238-48
  2. 2. Sicherer et al.JACI 2008;122:29-33
  3. 4. Does breastfeeding protect against development of atopy & asthma in childhood ? Objective To assess long-term outcomes of asthma & atopy related to breastfeeding in a New Zealand birth cohort study
  4. 5. Large unselected population-based birth cohort study 1,661 live-born 1,037 (91%) of 1,139 kids who were in Otago at age 3 y 5 7 9 11 13 15 18 21 26 yr SPT aeroallergen 69% 87% Verify BF record (investigators unaware of outcome) FH of allergy Comprehensive Questionnaire Spirometry Metacholine challenge/ Bronchodilator response test Investigators unaware of data for infant feeding determined all respiratory outcomes
  5. 6. <ul><ul><li>Current asthma = positive response to question “Do you (does your child) have asthma?” together with symptoms reported within previous 12 mo </li></ul></ul><ul><ul><li>SPT to Dp, cat, dog , horse hair, rye grass, kapok, wool, fungus (positive = wheal > 2 mm than negative control at 15 min) </li></ul></ul>Methods
  6. 7. Results <ul><ul><li>1,037 kids • early childhood characteristics not differ from 102 kids who did not participate </li></ul></ul><ul><ul><li>45% (463) not breastfed </li></ul></ul><ul><ul><li>7% (70) kids discontinued breastfed before 4 wk </li></ul></ul><ul><ul><li>Mean duration of BF in BF group = 21.1 wk (SD 16.6) </li></ul></ul><ul><ul><li>Term “BF” not necessarily mean exclusive BF </li></ul></ul>51% (533) BF < 4 wk 49% (504) BF >= 4 wk
  7. 8. Results <ul><ul><li>1,037 kids • early childhood characteristics not differ from 102 kids who did not participate </li></ul></ul><ul><ul><li>45% (463) not breastfed </li></ul></ul><ul><ul><li>7% (70) kids discontinued breastfed before 4 wk </li></ul></ul><ul><ul><li>Mean duration of BF in BF group = 21.1 wk (SD 16.6) : 4 wk until 47 wk </li></ul></ul><ul><ul><li>Term “BF” not necessarily mean exclusive BF </li></ul></ul>51% (533) BF < 4 wk 49% (504) BF >= 4 wk แบ่งตาม preliminary report : bias??
  8. 9. Characteristics of BF group <ul><ul><li>First-born </li></ul></ul><ul><ul><li>Higher socioeconomic status </li></ul></ul><ul><ul><li>Non-smoking mothers </li></ul></ul><ul><ul><li>More likely to have a sheepskin on their bed </li></ul></ul><ul><ul><li>Family history of hayfever or asthma (mother or father) and sex did not differ to non-BF group </li></ul></ul>Bias?
  9. 10. The effect with current asthma persisted at all ages to 26 years
  10. 12. Effect of BF not effected by FH
  11. 13. 1.72 --- 1.91 1.53 1.55 2.09 --- 2.54 1.86 1.73
  12. 14. Adjust SES, birth order, sheepskin use in infancy, maternal smoking
  13. 15. Conclusion <ul><ul><li>No duration of exclusive BF had a protective effect against development of atopy & asthma in later childhood </li></ul></ul><ul><ul><li>BF > 4 wks  likelihood of skin test response to common allergens at age 13 y and more than doubled the risk of diagnosed asthma in mid-childhood, with effects persisting into adulthood </li></ul></ul><ul><ul><li>Role of BF in protection of kids against atopy & asthma cannot be supported </li></ul></ul>
  14. 16. <ul><ul><li>Strength : </li></ul></ul><ul><ul><ul><li>26 year period of follow up </li></ul></ul></ul><ul><ul><ul><li>Criteria for diagnosis มี objective confirmation : Skin prick test (atopy) and lung funtion test (asthma) </li></ul></ul></ul><ul><ul><ul><li>Investigators ไม่รู้ outcome (no bias) </li></ul></ul></ul><ul><ul><ul><li>Adjustment of confounding variables </li></ul></ul></ul><ul><ul><ul><li>The strength of association : OR exceeding 2.0 mostly </li></ul></ul></ul><ul><ul><li>Weakness : </li></ul></ul><ul><ul><ul><li>Criteria การ define เรื่อง BF ไม่ชัดเจน แค่กินนมแม่ อาจกินนมผสมร่วมด้วย ก็ยังอยู่ใน BF group เพราะไม่มีข้อห้าม กินนมผสมปริมาณเท่าไหร่ก็ได้ร่วมกับนมแม่ ทำให้กลุ่มตัวอย่างมี heterogenitiy </li></ul></ul></ul><ul><ul><ul><li>Recall bias </li></ul></ul></ul><ul><ul><ul><li>High drop out rate </li></ul></ul></ul><ul><ul><ul><li>No data ก่อนอายุ 7 y </li></ul></ul></ul><ul><ul><ul><li>Prognostic factors ของ 2 กลุ่มแตกต่างกันตั้งแต่แรก </li></ul></ul></ul><ul><ul><ul><li>Criteria of positive skin test (2 mm?) : just sensitization </li></ul></ul></ul><ul><ul><ul><li>Selection of confounding factors </li></ul></ul></ul><ul><ul><ul><li>Self-selective bias </li></ul></ul></ul><ul><ul><ul><li>No data before age 9 y. </li></ul></ul></ul>
  15. 17. Appraising the Controversy & A Rebuttal Pete et al.Pediatric Pulmonology 2003.35:331-4 Sear et al.Pediatric Pulmonology 2003:36:366-8
  16. 18. Issues <ul><ul><li>Heterogenicity of breast feeding groups </li></ul></ul><ul><ul><li>Recall bias & unclear whether recalled reported were adjusted when the two methods differed </li></ul></ul><ul><ul><li>Reporting bias : most mothers aware that a longer duration of breastfeeding is desirable </li></ul></ul>
  17. 19. Answers Breast feeding data was recorded systematically by interviewers at 3 years old and were compared with data recorded prospectively by nurse with 98.9% agreement When data from nurse records were not provided : authors said they analyzed that it is not recall bias (how to?) Giving mothers the benefit of the doubt would not lead to any significant difference in outcomes (how to show?)
  18. 20. <ul><ul><li>Selection bias : hospital-based cohort & European ethnics only </li></ul></ul><ul><ul><li>Confounding factors </li></ul></ul><ul><ul><li>Causality : no dose response effect </li></ul></ul>
  19. 23. Population-based birth cohort study 14,062 live births 13,978 alive at age 1 y 3 4 7 8 SPT aeroallergen Verify BF record Access early childhood wheezing Spirometry & Metacholine challenge Ask whether diagnosed asthma
  20. 24. Methods 2 populations were accessed : - BF (never, <1 month, 1 to <3 months, 3 to <6 months, and >= 6 months) - Exclusive breast-feeding (never,<4 months, >= 4 months) SPT to 3 core aeroallergens (cat, mixed grass pollen, house dust mite) - positive >= 2 mm than negative control at 15 min)
  21. 27. 71.5 % Adjusted by sex, maternal age, maternal smoking, environmental tobacco smoke , maternal asthma, maternal allergy, and older siblings
  22. 28. Maternal age and maternal history of allergy : most important confounders 57 %
  23. 29. 55 %
  24. 30. Results Slightly protective effect of breast feeding on wheeze in early life did not extend into later childhood which is consistent with most other studies However no evidence of deleterious effect of breast feeding on atopic sensitization and later wheezing
  25. 31. <ul><ul><li>Bayesian joint model (reverse causation effect, loss follow-up group) </li></ul></ul><ul><ul><li>Reverse causation effect = children </li></ul></ul><ul><li>with early wheezing were more likely </li></ul><ul><li>to be breast-fed longer and to have </li></ul><ul><li>allergic outcomes </li></ul><ul><ul><li>Mean duration of breast-feeding for children </li></ul></ul><ul><li>who did not wheeze in the first 3 months of life was 6.6 months compared with 8.9 months for children with wheeze (P < .0001) </li></ul>Results
  26. 32. <ul><ul><li>modest difference in duration of breast-feeding based on early infant wheezing was not sufficient to bias the relationships between breast-feeding and the health outcomes examined </li></ul></ul><ul><ul><li>No evidence that the pattern of missing data in this study appreciably influenced outcome </li></ul></ul>Results
  27. 33. <ul><li>Benefits </li></ul><ul><ul><li>Large birth cohort study </li></ul></ul><ul><ul><li>Objective measurement </li></ul></ul><ul><ul><li>Bayesian joint model </li></ul></ul><ul><li>Weakness </li></ul><ul><ul><li>High drop-out rate </li></ul></ul><ul><ul><li>Criteria definition of atopy </li></ul></ul>
  28. 34. Even breast feeding does not protect asthma or atopy in later life Breastfeeding is a natural phenomenon, providing balanced nutrition and mother–infant bonding, as well as a number of health benefits Breast feeding is still preferable method for infantile feeding