Can a management pathway for chronic cough in children improve clinical outcomes: protocol for a multicentre evaluation.

BACKGROUND: Chronic cough is common and is associated with significant economic and human costs. While cough can be a problematic symptom without serious consequences, it could also reflect a serious underlying illness. Evidence shows that the management of chronic cough in children needs to be improved. Our study tests the hypothesis that the management of chronic cough in children with an evidence-based management pathway is feasible and reliable, and improves clinical outcomes. METHODS/DESIGN: We are conducting a multicentre randomised controlled trial based in respiratory clinics in 5 major Australian cities. Children (n = 250) fulfilling inclusion criteria (new patients with chronic cough) are randomised (allocation concealed) to the standardised clinical management pathway (specialist starts clinical pathway within 2 weeks) or usual care (existing care until review by specialist at 6 weeks). Cough diary, cough-specific quality of life (QOL) and generic QOL are collected at baseline and at 6, 10, 14, 26, and 52 weeks. Children are followed-up for 6 months after diagnosis and cough resolution (with at least monthly contact from study nurses). A random sample from each site will be independently examined to determine adherence to the pathway. Primary outcomes are group differences in QOL and proportion of children that are cough free at week 6. DISCUSSION: The clinical management pathway is based on data from Cochrane Reviews combined with collective clinical experience (250 doctor years). This study will provide additional evidence on the optimal management of chronic cough in children. TRIAL REGISTRATION: ACTRN12607000526471.

Cross-sectional and longitudinal association of the secretoglobin 1A1 gene A38G polymorphism with asthma phenotype in the Perth Infant Asthma Follow-up cohort.

BACKGROUND: Associations between Clara cell secretory protein gene variants (SCGB1A1, also known as CC16, CC10, CCSP and uteroglobin) and the asthma phenotype have been found in five out of eight studies world-wide. No study has investigated the contribution of SCGB1A1 polymorphisms to the development and/or persistence of the asthma phenotype in a birth cohort followed over time. OBJECTIVE: The aim of this study was to determine the role of the SCGB1A1 gene in the development of the asthma phenotype. METHODS: The Perth Infant Asthma Follow-up (PIAF) cohort (n=231 unrelated infants, unselected for asthma and recruited at birth) were seen at 1 month, 6 and 11 years of age, and had a questionnaire, lung function, airway responsiveness (AR) and skin prick tests (SPTs) completed. Blood was taken at 6 and 11 years for total and specific immunoglobulin E (sIgE) and DNA extraction. SPT positivity had at least one positive SPT. SIgE>4 kU/L had at least one sIgE above 4 kU/L. SCGB1A1 A38G (rs3741240), that alters gene transcription, was genotyped using Sau96I restriction digestion of exon 1 PCR products. RESULTS: At 6 and 11 years of age, 33.0% and 29.7% of those genotyped had doctor-diagnosed asthma, and 35.8% and 52.1% had SPT positivity. In cross-sectional analyses, children with 38G/38A or 38A/38A had increased AR at 1 month (1.72-fold, P=0.013); sIgE>4 kU/L [odds ratio (OR)=6.95, 95% confidence interval (CI)=1.35-35.91, P=0.021]; house dust mite (HDM) SPT positivity (OR=7.21, 95% CI=1.09-47.78, P=0.041) and sIgE (4.57-fold, P=0.045) at 6 years; and doctor-diagnosed asthma (OR=3.93, 95% CI=1.24-12.47, P=0.02) and cat SPT positivity (OR=4.34, 95% CI=1.01-18.77, P=0.049) at 11 years. Longitudinal analyses of 6 and 11 years paired data showed that children with 38A/38A had increased persistent sIgE>4 kU/L (OR=11.87, 95% CI=1.97-71.53, P=0.007) and persistent HDM SPT positivity (OR=7.84, 95% CI=1.04-58.92, P=0.045). CONCLUSION: SCGB1A1 A38G may play a role in the development and persistence of the asthma phenotype in childhood.

Perinatal and childhood origins of cardiovascular disease.

BACKGROUND: Features of the metabolic syndrome comprise a major risk for cardiovascular disease and will increase in prevalence with rising childhood obesity. We sought to identify early life influences on development of obesity, hypertension and dyslipidemia in children. METHODS AND RESULTS: Cluster analysis was used on a subset of a longitudinal Australian birth cohort who had blood samples at age 8 (n=406). A quarter of these 8-year-olds fell into a cluster with higher body mass index, blood pressure (BP), more adverse lipid profile and a trend to higher serum glucose resembling adult metabolic syndrome. There was a U-shaped relationship between percentage of expected birth weight (PEBW) and likelihood of being in the high-risk cluster. The high-risk cluster had elevated BP and weight as early as 1 and 3 years old. Increased likelihood of the high-risk cluster group occurred with greatest weight gain from 1 to 8 years old (odds ratio (OR)=1.4, 95% confidence interval (CI)=1.3-1.5/kg) and if mothers smoked during pregnancy (OR=1.82, CI=1.05-3.2). Risk was lower if children were breast fed for >/=4 months (OR=0.6, 95% CI=0.37-0.97). Newborns in the upper two quintiles for PEBW born to mothers who smoked throughout pregnancy were at greatest risk (OR=14.0, 95% CI=3.8-51.1) compared to the nadir PEBW quintile of non-smokers. CONCLUSION: A U-shaped relationship between birth weight and several components of the metabolic syndrome was confirmed in a contemporary, well-nourished Western population of full-term newborns, but post-natal weight gain was the dominant factor associated with the high-risk cluster. There was a prominence of higher as well as lowest birth weights in those at risk. Future health programs should focus on both pre- and post-natal factors (reducing excess childhood weight gain and smoking during pregnancy), and possibly the greatest benefits may arise from targeting the heaviest, as well as lightest newborns, especially with a history of maternal smoking during pregnancy.

The effect of age on the relationship between birth order and immunoglobulin E sensitization.

BACKGROUND: An association between birth order and IgE sensitization or allergic diseases has been reported in many studies. OBJECTIVE: To assess the effect of age on the relationship between reduced IgE sensitization and increased birth order and to test the hypothesis that this would decline with increasing age. METHODS: As part of a birth cohort study, IgE sensitization to common allergens was determined by skin prick testing at ages 6 and 12 months, 6 and 11 years. RESULTS: The original cohort numbered 253 individuals of whom 96 (38%) were first born. Compared with individuals with older siblings, first-born individuals had increased IgE sensitization at 6 (odds ratio (OR) 2.4 [95% confidence interval (CI) 1.0, 6.3], P=0.05, n=197) and 12 months of age (OR 6.7 [1.7, 25.0] P=0.002, n=172) and at 6 years of age (OR 2.3 [1.0, 5.6] P=0.05, n=113) but not at 11 years of age (OR 1.2, P>0.4, n=182). When age at onset of IgE sensitization was considered (n=61), 16 had infant onset IgE sensitization (nine were first born), 24 had early childhood onset IgE sensitization (nine first born) and 21 had late childhood onset IgE sensitization (two first born), P=0.0016. Further analysis revealed a similar pattern for children with older brothers (P=0.0097) but not older sisters (P=0.5). CONCLUSIONS: These findings indicated that having an older brother delays the onset of IgE sensitization but may not prevent IgE sensitization per se. The apparent protective effect of older siblings on allergic diseases reported elsewhere might involve delaying the onset of IgE sensitization.

Determinants of airway responsiveness to histamine in children.

Increased airway responsiveness (AR) is associated with asthma, but not all individuals with increased AR have asthma. The aim of this study was to identify factors, other than physician-diagnosed asthma (PDA), which are associated with increased AR. In a longitudinal study, data were collected on atopy and lower respiratory tract illness (LRTI) in infancy, and AR (expressed as dose-response slope (DRS)), atopy, tobacco-smoke exposure and PDA in childhood. At age 6 yrs, DRS was assessed in 102 children, of whom 22 (22%) had PDA; the corresponding figures at 11 yrs of age were 176 and 29 (15%). At age 6 yrs, DRS was significantly associated with PDA, current atopy and parental smoking (n = 83). At age 11 yrs, DRS was significantly associated with PDA, current atopy and LRTI in the first six months (n = 75). There was a significant positive interaction between atopy at age 12 months and PDA age 11 yrs. In conclusion, these data suggest that factors other than asthma or atopy may determine the level of airway responsiveness in children. In children with asthma, airway responsiveness may be influenced by the early onset of atopy. The current findings may explain the inconsistent relationship between airway responsiveness and asthma.

Predictors of body mass index and associations with cardiovascular risk factors in Australian children: a prospective cohort study.

OBJECTIVE: To examine predictors of body mass index (BMI) at the age of 8 y in a prospective study of Australian children. DESIGN: Longitudinal survey of a cohort of Australian children followed from the 16th week of gestation to 8 y. SUBJECTS: In total, 741 boys and 689 girls who attended the survey as 8 y olds. MEASUREMENTS: Weight and height, blood pressure measured by automated oscillometry, fasting blood lipids and glucose. Questionnaire assessment of activity and diet. RESULTS: Proportions of overweight including obesity in boys and girls were, respectively, 22 and 25% at 1 y, 14 and 14% at 3 y, 13 and 18% at 5 y and 15 and 20% at 8 y. At the age of 1, 3, 6 and 8 y, children with overweight including obesity showed significantly more adverse cardiovascular risk factors. Blood pressure (BP) was significantly higher by 2/3 mmHg (systolic/diastolic) at 1 y, 3/2 mmHg at 3 y, 4/2 mmHg at 5 y and 6/2 mmHg at 8 y; HDL was significantly lower (P=0.002) by 8% and triglycerides were significantly higher by 27% (P<0.001). In multivariate regression, BMI at the age of 8 y was significantly predicted positively by birth weight, mother's BMI and hours spent in watching television at the time of the survey of 6 y olds. Mothers being ex-smokers or non smokers and children being 'slightly active' and 'active' negatively predicted BMI in 8 y olds. In a subset of 298 children with information about fathers, paternal BMI was an additional independent predictor. Maternal or paternal overweight including obesity each independently increased risk of overweight including obesity at the age of 8 y three-fold. A food factor with consumption of cereals and breads as the major components derived from a Food Frequency Questionnaire in a subset of 340 children was also an independent negative predictor of BMI in multivariate models. CONCLUSION: The increasing rate of overweight including obesity, particularly in girls, is associated with an increase in cardiovascular risk factors very early in life. Improvement of health-related behaviours within the family and a focus on promotion of activity in children should be priorities in achieving weight control.

beta2 adrenoceptor Arg16Gly polymorphism, airway responsiveness, lung function and asthma in infants and children.

BACKGROUND: We have previously reported a relationship between increased airway responsiveness (AR) in infancy and reduced childhood lung function. OBJECTIVE: The current study aimed to determine whether the Arg16Gly polymorphism of the beta2 adrenoceptor (beta2AR) gene was important to this relationship. METHODS: A cohort that initially numbered 253 individuals underwent assessments of AR and lung function aged 1 month, 6 and 11 years; genotyping for polymorphisms of the beta(2)AR was performed. RESULTS: At 1 month of age, the genotype homozygous Arg16 (n=24) was associated with a mean increase in log dose-response slope (AR) of 0.27 [95% confidence interval (CI) 0.07, 0.49] compared with the genotype homozygous Gly16 (n=58), P=0.01. At 11 years of age, the genotype homozygous Arg16 (n=35) was associated with a mean reduction in the percentage of forced expiratory volume in 1 s of 5.3% [95% CI 0.3, 10.2] compared with the genotype homozygous Gly16 (n=65), P=0.03. There was no association between the Arg16Gly polymorphism and atopy or diagnosed asthma. However, nine of 69 individuals with the genotype homozygous Gly16 were admitted to hospital with asthma compared with five out of 111 individuals with the remaining genotypes (P<0.05). CONCLUSION: The Arg16Gly polymorphism may be important to the association between increased AR in infancy and reduced lung function in childhood and may also be a determinant of asthma severity in children but not asthma per se.

Breast feeding and respiratory morbidity in infancy: a birth cohort study.

AIM: To examine the relation between the duration of breast feeding and morbidity as a result of respiratory illness and infection in the first year of life. METHODS: Prospective birth cohort study of 2602 live born children ascertained through antenatal clinics at the major tertiary obstetric hospital in Perth, Western Australia. Main outcome measures were hospital, doctor, or clinic visits, and hospital admissions for respiratory illness and infection in the first year of life. Main exposure measures were the duration of predominant breast feeding (defined as the age other milk was introduced) and partial (any) breast feeding (defined as the age breast feeding was stopped). Main confounders were gender, gestational age less than 37 weeks, smoking in pregnancy, older siblings, maternal education, and maternal age. RESULTS: Hospital, doctor, or clinic visits for four or more upper respiratory tract infections were significantly greater if predominant breast feeding was stopped before 2 months or partial breast feeding was stopped before 6 months. Predominant breast feeding for less than six months was associated with an increased risk for two or more hospital, doctor, or clinic visits and hospital admission for wheezing lower respiratory illness. Breast feeding for less than eight months was associated with a significantly increased risk for two or more hospital, doctor, or clinic visits or hospital admissions because of wheezing lower respiratory illnesses. CONCLUSIONS: Predominant breast feeding for at least six months and partial breast feeding for up to one year may reduce the prevalence and subsequent morbidity of respiratory illness and infection in infancy.

Reduced lung function both before bronchiolitis and at 11 years.

BACKGROUND AND AIMS: We have previously shown an association between reduced premorbid lung function (V'maxFRC) and bronchiolitis. We hypothesised that individuals with bronchiolitis will go on to have reduced lung function and increased respiratory symptoms in childhood. METHODS: V'maxFRC was measured at 1 month of age; individuals with bronchiolitis were prospectively identified. Annual symptom questionnaires were completed from 3 to 6 years. At 11 years of age, children underwent an assessment including questionnaire, lung function, airway response to histamine (AR), and skin prick testing. RESULTS: Eighteen individuals with bronchiolitis were ascertained from 253 cohort members. Children with bronchiolitis had increased viral induced wheeze at 3 (OR 5.8, 95% CI 1.4 to 25.2; n = 103) and 5 years (OR 5.3, 95% CI 1.1 to 25.5; n = 101). At 11 years of age, 194 children were assessed including 16 with past bronchiolitis. These 16 individuals had reduced mean z scores for % V'maxFRC compared with other children (-0.56 and 0.06 respectively) and mean z scores for % FEF(25-75) at 11 years (-0.53 and 0.06 respectively). At 11 years, FEV(1), FVC PEF, AR, atopy, wheeze, and diagnosed asthma were not different between groups. CONCLUSIONS: Reduced lung function is present before and after bronchiolitis; the level of reduction is comparable. The mechanism for wheeze and reduced lung function after bronchiolitis appears to be related to premorbid lung function and not bronchiolitis per se.

Prenatal ultrasound biometry related to subsequent blood pressure in childhood.

STUDY OBJECTIVE: To relate measures of fetal growth/size other than birth weight with subsequent blood pressure measured on the same individuals within the context of the "fetal origins of adult disease". DESIGN: A prospective cohort study in which measurements of fetal dimensions obtained by serial ultrasound imaging between 18 and 38 weeks gestation were analysed with reference to systolic blood pressure measurements on the offspring at age 6 years. SETTING: Perth, Western Australia. PARTICIPANTS: A subgroup of 707 eligible mother-fetus pairs from a cohort of 2876 pregnant women and their offspring. The number of mother-fetus pairs varied at each gestational age and by measurement of fetal dimension. Subsequent blood pressure recordings were obtained on approximately 300 of the offspring at age 6 years. MAIN RESULTS: The findings confirmed the inverse association between birth weight and systolic blood pressure at age 6. There was, also, an inverse relation between fetal femur length and systolic blood pressure at age 6, adjusted for current height. Furthermore, an inverse association was demonstrated between a statistically derived measure of fetal growth (conditional z score) between 18 and 38 weeks gestation and later systolic blood pressure at age 6. The effect sizes for all three relations were in the order of 1-2 mm Hg per standard deviation change. CONCLUSION: The mechanisms underpinning the "fetal origins" hypothesis may be operative early in pregnancy and may be reflected in the length of the fetal femur in early to mid-pregnancy.

Placental weight and placental ratio as predictors of later blood pressure in childhood.

OBJECTIVE: A significant inverse relationship between blood pressure and birth weight is firmly established. This association may be the result of fetal adaptations to an adverse intrauterine environment. Further markers of intrauterine growth include the weight of the placenta and the placental ratio (the ratio of placental weight to birth weight). A number of studies suggest that a decreased placental weight or an elevated placental ratio may be independent risk factors for subsequent high blood pressure. The overall evidence for this is, however, inconclusive. The purpose of the present study was to clearly define the relationships between placental weight, placental ratio and subsequent blood pressure during childhood. DESIGN: Prospective cohort study of 2507 singleton children, born at term during 1989-1992. Blood pressures were recorded at ages 1, 3 and 6 years, using a semi-automated oscillometric device. RESULTS: Inverse relationships existed between both systolic and diastolic blood pressure and placental weight, adjusted for current weight at ages 1, 3 and 6 years. The relationships between placental weight and systolic blood pressure were statistically significant at ages 1 and 3 years. There was no consistent relationship between placental weight and later blood pressure within birth weight categories. No clinically or statistically significant association was seen between the placental ratio and either systolic or diastolic blood pressures at any age. CONCLUSIONS: Birth weight, rather than placental weight or their ratio, is the early life factor most importantly related to subsequent blood pressure in childhood.

Airway responsiveness in early infancy predicts asthma, lung function, and respiratory symptoms by school age.

Asthma is the most common chronic childhood disease in developed nations. Little is known about the relationship between airway responsiveness in infancy and the development of asthma later in life. The relationship of airway responsiveness at 1 mo with asthma, atopy, lower respiratory symptoms, and lung function at 6 yr of age was investigated prospectively in 95 white children from a randomly ascertained birth cohort. Baseline spirometry, airway responsiveness to histamine, and skin reactivity to common allergens were assessed at the age of 1 mo and 6 yr. Total serum immunoglobulin E (IgE) was measured from cord blood and at 6 yr. Blood eosinophil counts were measured at 6 yr only. Family, symptom, and exposure histories at both time points were derived from questionnaire data. Independently of the other factors assessed, increased airway responsiveness at 1 mo was significantly associated with the following parameters measured at six yr: decreased FEV(1) (p < 0.001); decreased FVC (p < 0.001); physician-diagnosed asthma (p < 0.001); and lower respiratory tract symptoms (p < 0.05). None of the other physiologic factors measured in infancy showed such consistent associations with important clinical and physiologic outcomes at age 6. These data suggest that airway responsiveness in early life defines a functional state that is associated with abnormal airway function, lower respiratory symptoms, and the emergence of asthma by 6 yr of age.

Parental smoking: asthma and wheezing illnesses in infants and children.

Parental smoking has an important impact on asthma and wheezing illnesses in infants and children. In utero exposure is associated with impaired lung growth and wheezing illnesses, particularly in preschool children. Exposure to environmental tobacco smoke is associated with increased wheezing illnesses and increased symptoms in asthmatics. There are no consistent data to confirm an effect of in utero or postnatal cigarette smoke exposure on the prevalence of asthma but there is evidence of increased severity of symptoms. The detrimental effects of parental smoking on lung growth will have an impact on respiratory health throughout life.

Adjustment for current weight and the relationship between birth weight and blood pressure in childhood.

OBJECTIVE: To determine the role of current weight in mediating the relationship between birth weight and blood pressure within the context of the 'fetal origins' hypothesis. DESIGN: Prospective cohort study of 2507 pregnant women and their singleton offspring, delivered live at term, in Perth, Western Australia between 1989 and 1992. The study commenced at 16 weeks gestation with serial weight and blood pressure measurements recorded through early childhood. RESULTS: Inverse associations were found between birth weight and systolic blood pressure at ages 1, 3 and 6. The effect of birth weight on systolic blood pressure at age 6 reached statistical significance and was increased fourfold in magnitude to -2.3 mmHg [95% confidence interval = (-3.3 to -1.3), P < 0.01] after adjustment for current weight. The interaction term for birth weight and current weight was not statistically significant. Including intermediate weights did not produce a statistically significantly better model but did increase the magnitude of the estimated regression coefficient of birth weight on blood pressure, and only the birth weight and current weight terms were significant CONCLUSIONS: Adjustment for current weight serves to highlight the relationship between birth weight and blood pressure in childhood. Nevertheless, birth weight, rather than birth weight adjusted for current weight, is still the relevant predictor of later blood pressure within the context of the 'fetal origins' hypothesis.

Parental factors affecting respiratory function during the first year of life.

In a prospective, longitudinal, population-based cohort study of familial and environmental influences on the development of wheezing respiratory illness in early childhood, we identified infant length, weight, gender, and exposure to maternal cigarette smoking as significant determinants of lung function during the first year of life. A cohort of 237 infants (106 females: 131 males) was evaluated, and 496 lung function measurements were made between the ages of 1-12 months. Respiratory function was assessed using the rapid thoracic compression technique to obtain maximum expiratory flow at functional residual capacity (V'maxFRC). Parental history of asthma and smoking habits during pregnancy were obtained by questionnaire. Data were analyzed using a longitudinal random effects model. Infants with a parental history of asthma and/or in utero passive smoke exposure were compared to a reference group of infants who had no parental history of asthma and in whom neither parent smoked pre- or postnatally. Boys were found to have a consistently lower V'maxFRC (-21.05 mL.s(-1)) throughout the first year of life in comparison to girls (P < 0.05). Maternal smoking during pregnancy was associated with a lower V'maxFRC in both genders in comparison to unexposed infants (P < 0.05). V'maxFRC was unaffected by parental history of asthma. Gender-specific normative equations for V'maxFRC throughout the first year of life were derived for the infant cohort as a whole and also for subgroups of infants, based on parental asthma and smoking history. We conclude that lung function during the first year of life differs between genders and is adversely affected by in utero passive tobacco smoke exposure. Gender-specific predictive equations for V'maxFRC should be used during infancy.

Maternal cigarette smoking during pregnancy, low birth weight and subsequent blood pressure in early childhood.

Given the widely acknowledged inverse relationship between birth weight and blood pressure, a raised blood pressure in the offspring of smoking mothers as compared to those whose mothers did not smoke, would be anticipated by virtue of the reduction in birth weight associated with smoking during pregnancy. The objective of the present study was to test the hypothesis that maternal cigarette smoking during pregnancy has an effect on blood pressure in childhood independent of its effect on birth weight. Data was obtained from a prospective cohort study of 1708 pregnant women and their singleton offspring, delivered live at term, in Perth, Western Australia, commenced at 16 weeks gestation with serial blood pressure measurements through early childhood. Statistically significant associations were found between maternal smoking during pregnancy and systolic blood pressure at age six, between birth weight and systolic blood pressure at ages three and six, and between maternal smoking during pregnancy and birth weight. The relationship between birth weight and blood pressure in early childhood differed significantly on the basis of maternal cigarette smoking or not during pregnancy. This differential relationship persisted after adjustment for the child's current weight and socio-economic status. We concluded that intra-uterine exposure to maternal cigarette smoking increased children's blood pressure at age one through to age six. This was not wholly attributable to an effect on birth weight or confounding of the association between birth weight and subsequent blood pressure by the child's current weight or socio-economic factors. Furthermore, maternal smoking during pregnancy does not account for the acknowledged elevation in blood pressure associated with low birth weight. The present study is an exploration of a possible causal pathway underlying the birth weight/blood pressure association rather than simply a confirmation of such an association which has been detailed in many other papers.

Reference ranges for blood pressure in preschool Australians, obtained by oscillometry.

OBJECTIVE: To derive reference centiles for blood pressure in children aged 1-6 years which seek to address shortcomings in available reference ranges. METHODS: Prospective cohort study of 2876 children in Perth, Western Australia, commenced in 1989 with serial blood pressure measurements through early childhood obtained by oscillometry under standardized conditions. RESULTS: Gender-specific reference centile charts for systolic and diastolic blood pressure, (i) across ages 1-6 years and (ii) across the range of corrected Body Mass Index values at ages 1, 3 and 6 years, were generated by fitting linear models with both fixed and random effects. CONCLUSIONS: Reference values for blood pressure for young children are of clinical use and may be of long-term predictive value.

The association between early life lung function and wheezing during the first 2 yrs of life.

Reports have suggested that certain infants are predisposed to wheezing in the first 2 yrs of life due to abnormal lung function, prior to the first wheezing illness. The authors investigated the association between infant lung function and wheeze during the first 2 yrs of life. A cohort of 253 infants was evaluated. Respiratory function assessment was performed at 1, 6, and 12 months of age. Parental history of asthma, atopy, and maternal antenatal smoking habits were recorded. An infant was identified as having wheezed on the basis of parental report and, where possible, physician diagnosis. One hundred and sixty infants (63%) had complete diary and questionnaire information on wheeze available for analysis. Of these: 79 infants (50%) had never wheezed (NW) during the first 2 yrs of life and 81 had reported wheeze (W) (50%). Of those with a report of wheeze, the distribution through the first 2 yrs of life was; 28 during the first year of life only (Y1), 21 in the second year of life only (Y2), and 32 wheezed in both the first and second years of life (Y1&2). At the age of 1 month, prior to any lower respiratory illness, the W group had impaired lung function in comparison to the NW group. In Y1 infants, the neonatal lung function differences resolved by 12 months of age. In Y2 and Y1&2 infants lung function differences persisted throughout the first year of life. Prevalence of parental asthma and maternal antenatal smoking was increased in the W group p=0.001, p=0.008, respectively), in comparison to the NW infants. Maternal antenatal smoking prevalence was increased in the Y2 and Y1&2 infants in comparison to the NW group (p=0.04), (p=0.01), respectively. Wheezing during the first year of life is often a transient condition which improves with time. It appears to be related to early life reduced small airway calibre. Wheezing that begins or persists into the second year of life is usually associated with a different abnormality of the airways. Commencement or persistence of wheeze into the second year of life may be part of the clinical entity recognized as asthma.

Association between breast feeding and asthma in 6 year old children: findings of a prospective birth cohort study.

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.