Dojčenie a astma

  Výsledky viacerých prác naznačujú, že dojčenie prinajmenšom do 4-6 mesiacov veku chráni deti do určitej miery pred rozvojom astmy. Včasné zavádzanie príkrmov je spojené s vyšším rizikom bronchiálnej astmy. Ako prevenciu astmy v detskom veku preto možno jednoznačne odporučiť výlučné dojčenie aspoň počas prvého polroka života.

Association between breast feeding and asthma in 6 year old children: findings of a prospective birth cohort study. 
Oddy WH, Holt PG, Sly PD, Read AW, Landau LI, Stanley FJ, Kendall GE, Burton PR 
TVW Telethon Institute for Child Health Research, West Perth, Western Australia, Australia 6872.
OBJECTIVES: To investigate the association between the duration of exclusive breast feeding and the development of asthma related outcomes in children at age 6 years. DESIGN: Prospective cohort study. SETTING: Western Australia. SUBJECTS: 2187 children ascertained through antenatal clinics at the major tertiary obstetric hospital in Perth and followed to age 6 years. MAIN OUTCOME MEASURES: Unconditional logistic regression to model the association between duration of exclusive breast feeding and outcomes related to asthma or atopy at 6 years of age, allowing for several important confounders: sex, gestational age, smoking in the household, and early childcare. RESULTS: After adjustment for confounders, the introduction of milk other than breast milk before 4 months of age was a significant risk factor for all asthma and atopy related outcomes in children aged 6 years: asthma diagnosed by a doctor (odds ratio 1.25, 95% confidence interval 1.02 to 1.52); wheeze three or more times since 1 year of age (1.41, 1.14 to 1.76); wheeze in the past year (1.31, 1.05 to 1.64); sleep disturbance due to wheeze within the past year (1.42, 1.07 to 1.89); age when doctor diagnosed asthma (hazard ratio 1.22, 1.03 to 1.43); age at first wheeze (1.36, 1.17 to 1.59); and positive skin prick test reaction to at least one common aeroallergen (1.30, 1.04 to 1.61). CONCLUSION: A significant reduction in the risk of childhood asthma at age 6 years occurs if exclusive breast feeding is continued for at least the 4 months after birth. These findings are important for our understanding of the cause of childhood asthma and suggest that public health interventions to optimise breast feeding may help to reduce the community burden of childhood asthma and its associated traits.

Breastfeeding as prophylaxis against atopic disease: prospective follow-up study until 17 years old. 
Saarinen UM, Kajosaari M 
Children's Hospital, Helsinki, Finland.
Atopic diseases constitute a common health problem. For infants at hereditary risk, prophylaxis of atopy has been sought in elimination diets and other preventive measures. We followed up healthy infants during their first year, and then at ages 1, 3, 5, 10, and 17 years to determine the effect on atopic disease of breastfeeding. Of the initial 236 infants, 150 completed the follow-up, which included history taking, physical examination, and laboratory tests for allergy. The subjects were divided into three groups: prolonged (> 6 months), intermediate (1-6 months), and short or no (< 1 month) breastfeeding. The prevalence of manifest atopy throughout follow-up was highest in the group who had little or no breastfeeding (p < 0.05, analysis of variance and covariance with repeated measures [ANOVA]). Prevalence of eczema at ages 1 and 3 years was lowest (p = 0.03, ANOVA) in the prolonged breastfeeding group, prevalence of food allergy was highest in the little or no groups (p = 0.02, ANOVA) at 1-3 years, and respiratory allergy was also most prevalent in the latter group (p = 0.01, ANOVA) having risen to 65% at 17 years of age. Prevalences in the prolonged, intermediate, and little or no groups at age 17 were 42 (95% CI 31-52)%, 36 (28-44)%, and 65 (56-74)% (p = 0.02, trend test) for atopy, respectively, and 8 (6-10)%, 23 (21-25)%, and 54 (52-56)% (p = 0.0001, trend test) for substantial atopy. We conclude that breastfeeding is prophylactic against atopic disease--including atopic eczema, food allergy, and respiratory allergy--throughout childhood and adolescence.

Relation of infant diet to childhood health: seven year follow up of cohort of children in Dundee infant feeding study. 
Wilson AC, Forsyth JS, Greene SA, Irvine L, Hau C, Howie PW 
Department of Child Health, Ninewells Hospital and Medical School, Dundee.
OBJECTIVE: To investigate the relation of infant feeding practice to childhood respiratory illness, growth, body composition, and blood pressure. DESIGN: Follow up study of a cohort of children (mean age 7.3 years) who had detailed infant feeding and demographic data collected prospectively during the first two years of life. SETTING: Dundee. SUBJECTS: 674 infants, of whom 545 (81%) were available for study. Data on respiratory illness were available for 545 children (mean age 7.3 (range 6.1-9.9) years); height for 410 children; weight and body mass index for 412 children; body composition for 405 children; blood pressure for 301 children (mean age 7.2 (range 6.9-10.0) years). MAIN OUTCOME MEASURES: Respiratory illness, weight, height, body mass index, percentage body fat, and blood pressure in relation to duration of breast feeding and timing of introduction of solids. RESULTS: After adjustment for the significant confounding variables the estimated probability of ever having respiratory illness in children who received breast milk exclusively for at least 15 weeks was consistently lower (17.0% (95% confidence interval 15.9% to 18.1%) for exclusive breast feeding, 31.0% (26.8% to 35.2%) for partial breast feeding, and 32.2% (30.7% to 33.7%) for bottle feeding. Solid feeding before 15 weeks was associated with an increased probability of wheeze during childhood (21.0% (19.9% to 22.1%) v 9.7% (8.6% to 10.8%)). It was also associated with increased percentage body fat and weight in childhood (mean body fat 18.5% (18.2% to 18.8%) v 16.5% (16.0% to 17.0%); weight standard deviation score 0.02 (-0.02 to 0.06) v -0.09 (-0.16 to 0.02). Systolic blood pressure was raised significantly in children who were exclusively bottle fed compared with children who received breast milk (mean 94.2 (93.5 to 94.9) mm Hg v 90.7 (89.9 to 91.7) mm Hg). CONCLUSIONS: The probability of respiratory illness occurring at any time during childhood is significantly reduced if the child is fed exclusively breast milk for 15 weeks and no solid foods are introduced during this time. Breast feeding and the late introduction of solids may have a beneficial effect on childhood health and subsequent adult disease.

Breastfeeding and asthma in children: findings from a West Australian study. 
Oddy WH 
TVW Telethon Institute for Child Health Research, West Perth, Western Australia. wendyo@ichr.uwa.edu.au
The primary aim was to determine whether there was an inverse association between the duration of exclusive breastfeeding and the development of traits associated with asthma in children at age six years. A prospective cohort study of children from Western Australia was enrolled prior to birth and followed to age six. Two thousand, nine hundred and seventy-nine children were recruited through antenatal clinics at the major tertiary obstetric hospital in Perth. Unconditional logistic regression was used to model the association between duration of exclusive breastfeeding and outcomes related to asthma or atopy at age six allowing for a number of important confounders. These included gender, gestational age, smoking in pregnancy and early child care. After adjustment for confounders, the introduction of milk other than breastmilk before four months of age was a significant (p < 0.05) risk factor for all asthma-related outcomes in six-year-old children: (i) doctor diagnosed asthma odds ratio OR = 1.25 (95% CI 1.02-1.54); (ii) wheeze three or more times since the age of one year OR 1.42 (1.15-1.76); (iii) wheeze in the last twelve months OR 1.28 (1.02-1.76); (iv) sleep disturbance due to wheeze within the last twelve months OR 1.41 (1.04-1.90); (v) age at doctor diagnosis (hazard ratio HR 1.22 1.03-1.43); (vi) age at first wheeze (HR 1.36 1.17-1.59) and; (vii) positive reaction to common aeroallergens OR 1.27 (1.01-1.59). There is a substantial reduction in risk of childhood asthma as assessed at age six years, if exclusive breastfeeding is continued for at least the first four months of life.These findings are important for our understanding of the aetiology of and for the potential prevention of asthma in children.

Relationship of infant feeding to recurrent wheezing at age 6 years. 
Wright AL, Holberg CJ, Taussig LM, Martinez FD 
Department of Pediatrics, University of Arizona, Tucson, USA.
OBJECTIVES: To investigate the relationship of infant feeding to recurrent wheezing at age 6 years and to assess whether this relationship is altered by a history of wheezing lower respiratory tract illnesses. DESIGN: Prospective, longitudinal study of healthy infants followed up from birth to 6 years of age. SETTING: Nonselected health maintenance organization population in Tucson, Arizona. PARTICIPANTS: There were 1246 healthy infants enrolled at birth, 988 of whom had data on both infant feeding and wheezing at age 6 years. INTERVENTIONS: None. MAIN OUTCOME MEASURES: Recurrent wheeze (four or more episodes in the past year) was assessed by a questionnaire that was completed by parents when the children were 6 years old. Children were classified by atopic status on the basis of skin prick tests. RESULTS: Breast-feeding information was collected prospectively, and lower respiratory tract illnesses in the first 3 years of life were diagnosed by the pediatrician. Being breast-fed was associated with lower rates of recurrent wheeze at age 6 years (3.1% vs 9.7%, P < .01) for nonatopic children; this relationship was not significant for atopic children. The relationship of breast-feeding with recurrent wheeze was apparent among nonatopic children both with and without a wheezing lower respiratory tract illness in the first 6 months of life. When potential confounders, including early wheezing lower respiratory tract illness, were included in a multivariate model, nonatopic children who had not been breast-fed had three times the odds of wheezing recurrently (odds ratio, 3.03; confidence interval, 1.06 to 8.69). Eleven percent of recurrent wheeze among nonatopic children could be attributed to not breast-feeding. CONCLUSIONS: Recurrent wheeze at age 6 years is less common among nonatopic children who were breast-fed as infants. This effect is independent of whether the child wheezed with a lower respiratory tract illness in the first 6 months of life.

Is primary prevention of asthma possible? 
Becker AB 
University of Manitoba, Winnipeg, Canada. becker@cc.umanitoba.ca
Two major factors are critical to the development of asthma: the individual's genetic background and the environment. The gene for asthma has not yet been identified. Thus, environmental factors appear to be the critical factors that can be controlled. Exposure to specific allergens is important. Ingestants may be the earliest initiating trigger for 'turn on' of allergy. Subsequently, sensitization to indoor inhalants becomes important in asthma. Among pollutants, environmental tobacco smoke (ETS) is most important. Finally, infections play a role in the development of asthma. Approaches to primary prevention include potential novel techniques such as vaccines or immunization. Dietary intervention appears to be important for atopic dermatitis but less so for asthma. Nevertheless, breastfeeding is successful in decreasing respiratory illness and should be encouraged. In terms of allergen avoidance, avoidance of indoor allergens, particularly house dust mite, cat and cockroach, have the greatest potential for benefit. Exposure to ETS in early life must be avoided. Asthma is a multifactorial disease, and complex interventions are likely to be required to decrease prevalence of this increasingly common disease.

Primary and secondary prevention of allergic asthma. 
Peat J, Bjorksten B 
Sydney University Dept of Pediatrics and Child Health, New Children's Hospital, Westmead, NSW, Australia.
The primary prevention of asthma requires environmental strategies aimed at reducing both the development of allergic sensitization and the development of asthma in those who have already become sensitized. The environmental interventions that would seem most promising at the current time are those which address exposure to indoor allergens and maternal smoking because there is consistent evidence of their effects. Several studies have demonstrated the effectiveness of allergen avoidance in preventing asthma and, because of the potential benefits of such interventions, it is important that they continue to be developed to improve both their acceptability and effectiveness. On the other hand, few studies have investigated the feasibility and efficacy of antismoking interventions during pregnancy and it remains important that new interventions are developed that specifically address smoking in this group. Because there is also some evidence that both breastfeeding and dietary factors are important in the aetiology of asthma, limited advice about their role can be given. Given the knowledge of the risk factors for asthma that we now have available, we have a responsibility to recommend preventive and potentially preventive strategies to parents whose children are at high risk for developing this illness.

Prevention of asthma. 
Peat JK 
Dept of Medicine, University of Sydney, NSW, Australia.
Environmental factors which have changed in the last decade or so appear to be largely responsible for the increase in the prevalence of asthma in affluent countries. It should, therefore, be possible to design interventions to reverse these recent trends and reduce the incidence of asthma. Primary preventive strategies have the potential not only to reduce acquisition of sensitization to common allergens and the risk that symptoms will develop subsequently, but also to reduce morbidity in those who already have persistent disease. There is accumulating epidemiological evidence that a dietary exess of sodium and omega-6 fatty acids, a dietary deficiency of antioxidant vitamins and omega-3 fatty acids, reduced rates of breastfeeding and exposure to allergens and environmental tobacco smoke are all involved in the aetiology of asthma. The modification of these factors has the potential to reduce the incidence and thus the prevalence of this disease. Environmental intervention should be particularly effective in children who have inherited or acquired characteristics which put them at high risk of developing asthma. With the evidence now available, it seems reasonable to assume that interventions which are based on our current knowledge of risk factors could achieve a 50% reduction in the prevalence of asthma in the next generation of children.

Lessons from long-term cohort studies. Childhood asthma. 
Wright AL, Taussig LM 
Dept of Pediatrics and Respiratory Sciences Center, University of Arizona, Tucson 85724, USA.
Cohort studies, which are longitudinal studies that follow a group of people with reference to the development of disease, have been a cornerstone of research on childhood asthma. These studies are uniquely suited to address questions concerning the incidence of illness, the natural history of disease, and the sequence of events linking exposures with outcomes. Three findings from on-going cohort studies are particularly relevant for the design of future intervention studies. First, most childhood asthma begins in infancy, with 80% of children who develop asthma having their first episode of wheeze before the age of 3 yrs. Second, events in early life, possibly including allergen exposure, infant feeding practices and viral infections, may be critical to the development of asthma in childhood. Finally, wheezing presents as separate phenotypes at different ages, with each phenotype having distinct characteristics, risk factors and prognoses. Additional cohort studies are required to determine to what extent events occurring in infancy, both viral and allergic, trigger expression of asthma, what are the mechanisms whereby they foster development of the disease, and whether their effect can be prevented.