Definition of respiratory symptoms and disease in early childhood in large prospective birth cohort studies that predict the development of asthma

Factors associated with wheezing among Lebanese children: Results of a cross-sectional study

BACKGROUND

In Lebanon, asthma is underdiagnosed due to low access to healthcare, particularly in rural areas, although asthma diagnosis in children is based mainly on clinical symptoms. Thus, wheezing might be more suggestive of undiagnosed respiratory diseases including asthma in Lebanese children. This study aimed to determine the factors associated with wheezing in Lebanese children without asthma diagnosis.

METHODS

This cross-sectional study was conducted between December 2015 and April 2016, enrolling a total of 1203 schoolchildren.

RESULTS

Out of 1500 prepared questionnaires, 1380 questionnaires were distributed in schools, and 1203 (87.17%) were collected back from the parents of children aged between 4-17 years old. The sample included 42 (3.5%) [95% CI 0.025-0.045] children with reported chronic wheezing. A multivariable analysis was performed taking the presence versus absence of wheezing in children as the dependent variable. The results showed that spraying pesticides at home (aOR=1.91), presence of humidity at home (aOR=2.21) and child reflux (aOR=2.60) were significantly associated with the presence of wheezing in children.

CONCLUSION

The findings of the study suggest that certain environmental factors, such as pesticides, humidity at home and reflux disease, might be associated with wheezing episodes in children. Those factors can be prevented through raising awareness by health care professionals.

Asthma phenotypes in children and stratified pharmacological treatment regimens

INTRODUCTION

Asthma is the most common inflammatory disease in childhood. The interaction of genetic, environmental and host factors may contribute to the development of childhood asthma and defines its progress, including persistence and severity. Until now, various classifications of childhood asthma phenotypes have been suggested based on patient's age during onset of symptoms, type of inflammatory cells, response to treatment and disease severity. Many efforts have been carried out to identify childhood asthma phenotypes and to clarify which are the risk factors that define asthma prediction and the response to therapy. The identification of asthma phenotypes has not only prognostic but also therapeutic role. However, the classification of asthma phenotypes is complex due to the heterogeneity of the disease. Areas covered: The current childhood asthma phenotypes and the new therapeutic strategies for each phenotype are reviewed. Expert commentary: There are multiple phenotypes in childhood asthma and it is crucial to define them before the initiation of personalized treatment. Both the therapeutic strategy and monitoring should follow the recent guidelines.

Nocturnal dry cough in the first 7 years of life is associated with asthma at school age

BACKGROUND

Childhood wheeze is an important, well-known risk factor for asthma, yet little is known about the contribution of nocturnal dry cough. We investigated the association of nocturnal dry cough at ages 1-7 years with doctor-diagnosed asthma at 8 years of age, both in the presence and absence of wheeze.

METHODS

Data of 3,252 children from the PIAMA birth cohort were studied. Parents reported the presence of nocturnal dry cough, wheeze, and doctor-diagnosed asthma in the past 12 months yearly, from birth up to the age of 8 years.

RESULTS

Nocturnal dry cough without wheeze was significantly associated with doctor-diagnosed asthma at age 8, except for age 1 (range of Relative Risks (RR) at ages 2-7: 1.8 (age 5) - 7.1 (age 7), all P-values <0.048). As expected, wheeze without nocturnal dry cough was strongly associated with doctor-diagnosed asthma at age 8 (range of RR: 2.0 (age 1) - 22.2 (age 7), all P-values <0.003). Of interest, nocturnal dry cough with wheeze showed the strongest association with doctor-diagnosed asthma at age 8 (range of RR: 3.7 (age 1) - 26.0 (age 7), all P-values <0.001). The relative excess risk of asthma at age 8 due to interaction of nocturnal dry cough with wheeze at age 1 year was 1.8 (0.1-3.6, P < 0.01).

CONCLUSION

Nocturnal dry cough and wheeze in early childhood are both independently associated with asthma at school age. The presence of both nocturnal dry cough and wheeze at age 1 almost doubles the risk of asthma at age 8 compared to wheeze alone.

Respiratory outcomes of the surfactant positive pressure and oximetry randomized trial (SUPPORT)

OBJECTIVE

To explore the early childhood pulmonary outcomes of infants who participated in the National Institute of Child Health and Human Development's Surfactant Positive Airway Pressure and Pulse Oximetry Randomized Trial (SUPPORT), using a factorial design that randomized extremely preterm infants to lower vs higher oxygen saturation targets and delivery room continuous positive airway pressure (CPAP) vs intubation/surfactant.

STUDY DESIGN

The Breathing Outcomes Study, a prospective secondary study to the Surfactant Positive Airway Pressure and Pulse Oximetry Randomized Trial, assessed respiratory morbidity at 6-month intervals from hospital discharge to 18-22 months corrected age (CA). Two prespecified primary outcomes-wheezing more than twice per week during the worst 2-week period and cough longer than 3 days without a cold-were compared for each randomized intervention.

RESULTS

One or more interviews were completed for 918 of the 922 eligible infants. The incidences of wheezing and cough were 47.9% and 31.0%, respectively, and did not differ between the study arms of either randomized intervention. Infants randomized to lower vs higher oxygen saturation targets had a similar risk of death or respiratory morbidity (except for croup and treatment with oxygen or diuretics at home). Infants randomized to CPAP vs intubation/surfactant had fewer episodes of wheezing without a cold (28.9% vs 36.5%; P<.05), respiratory illnesses diagnosed by a doctor (47.7% vs 55.2%; P<.05), and physician or emergency room visits for breathing problems (68.0% vs 72.9%; P<.05) by 18-22 months CA.

CONCLUSION

Treatment with early CPAP rather than intubation/surfactant is associated with less respiratory morbidity by 18-22 months CA. Longitudinal assessment of pulmonary morbidity is necessary to fully evaluate the potential benefits of respiratory interventions for neonates.

Prevalence and risk factors associated with wheezing in the first year of life

OBJECTIVE

to investigate the prevalence and risk factors associated with wheezing in infants in the first year of life.

METHODS

this was a cross-sectional study, in which a validated questionnaire (Estudio Internacional de Sibilancias en Lactantes--International Study of Wheezing in Infants--EISL) was applied to parents of infants aged between 12 and 15 months treated in 26 of 85 primary health care units in the period between 2006 and 2007. The dependent variable, wheezing, was defined using the following standards: occasional (up to two episodes of wheezing) and recurrent (three or more episodes of wheezing). The independent variables were shown using frequency distribution to compare the groups. Measures of association were based on odds ratio (OR) with a confidence interval of 95% (95% CI), using bivariate analysis, followed by multivariate analysis (adjusted OR [aOR]).

RESULTS

a total of 1,029 (37.7%) infants had wheezing episodes in the first 12 months of life; of these, 16.2% had recurrent wheezing. Risk factors for wheezing were family history of asthma (OR=2.12; 95% CI: 1.76-2.54) and six or more episodes of colds (OR=2.38; 95% CI: 1.91-2.97) and pneumonia (OR=3.02; 95% CI: 2.43-3.76). For recurrent wheezing, risk factors were: familial asthma (aOR=1.73; 95% CI 1.22-2.46); early onset wheezing (aOR=1.83; 95% CI: 1.75-3.75); nocturnal symptoms (aOR=2.56; 95% CI: 1.75-3.75), and more than six colds (aOR=2.07; 95% CI 1.43- .00).

CONCLUSION

the main risk factors associated with wheezing in Fortaleza were respiratory infections and family history of asthma. Knowing the risk factors for this disease should be a priority for public health, in order to develop control and treatment strategies.

Fish consumption in infancy and asthma-like symptoms at preschool age

OBJECTIVE

To assess whether timing of introduction of fish and the amount of fish consumption in infancy were associated with asthmalike symptoms at preschool age.

METHODS

This study was embedded in the Generation R study (a population-based birth cohort in Rotterdam, Netherlands). At the age of 12 and 14 months, timing of introduction of fish into the infant's diet was assessed. The amount of fish consumption at 14 months was assessed by a semiquantitative food frequency questionnaire. Presence of asthmalike symptoms in the past year was assessed at the child's age of 36 and 48 months.

RESULTS

Relative to no introduction in the first year of life, introduction between age 6 and 12 months was significantly associated with a lower risk of wheezing at 48 months (odds ratio [OR]: 0.64; 95% CI: 0.43-0.94). When compared with introduction between 6 and 12 months, no introduction in the first year and introduction between 0 and 6 months were associated with an increased risk of wheezing at 48 months (OR: 1.57; 95% CI: 1.07-2.31 and OR: 1.53; 95% CI: 1.07-2.19, respectively). The amount of fish at age 14 months was not associated with asthmalike symptoms (P > .15).

CONCLUSIONS

Introduction of fish between 6 and 12 months but not fish consumption afterward is associated with a lower prevalence of wheezing. A window of exposure between the age of 6 and 12 months might exist in which fish might be associated with a reduced risk of asthma.

T1 and T2 ADAM33 single nucleotide polymorphisms and the risk of childhood asthma in a Saudi Arabian population: a pilot study

BACKGROUND AND OBJECTIVES

Genetic association studies have demonstrated that over 100 variants in target genes (including ADAM33) are associated with airway remodeling and hyper-responsiveness in different ethnic groups; however, this has never been evaluated in Arabic populations. The objective of this study was to determine whether ADAM33 polymorphisms that are associated with asthma in a population of asthmatic children from Saudi Arabia.

DESIGN AND SETTING

A cross-sectional pilot study comparing the polymorphisms of normal subjects and asthmatic patients from Saudi Arabia over a period of 1 year.

PATIENTS AND METHODS

One hundred and seven Saudi asthmatic children and 87 healthy Saudi children of 3-12 years old were assessed for allelic association of ADAM33 T1 (rs2280091), T2 (rs2280090), ST+4 (rs44707) and S1 (rs3918396) SNPs to asthma. Genotyping was done by real-time PCR, multiplex ARMS and PCR-RFLP.

RESULTS

T1 and T2 SNP genotype frequencies in asthmatic children were significantly different compared to controls (P < .05), indicating allelic association with asthma. The T1 A/G and G/G and the T2 A/G and A/A genotypes (P=.0013 and P=.008, respectively) but not S1 and ST+4, increased the risk of asthma when using the best fit dominant model. Strong linkage disequilibrium between T1 (rs2280091) and T2 (rs2280090) was observed (r2=0.83; D'=0.95; P < .001). The haplotype G-A-A-C was significantly more frequent in asthmatics, thus supporting the association of T1 G-allele and T2 A-allele with increased predisposition to asthma (P=.007).

CONCLUSIONS

T1 A/G and T2 G/A ADAM33 polymorphisms, but not S1 or ST+4, were significantly associated with asthma development in Saudi children, like those reported for white and Hispanic populations in the United States.

Early detection and counselling intervention of asthma symptoms in preschool children: study design of a cluster randomised controlled trial

BACKGROUND

Prevention of childhood asthma is an important public health objective. This study evaluates the effectiveness of early detection of preschool children with asthma symptoms, followed by a counselling intervention at preventive child health centres. Early detection and counselling is expected to reduce the prevalence of asthma symptoms and improve health-related quality of life at age 6 years.

METHODS/DESIGN

This cluster randomised controlled trial was embedded within the Rotterdam population-based prospective cohort study Generation R in which 7893 children (born between April 2002 and January 2006) participated in the postnatal phase. Sixteen child health centres are involved, randomised into 8 intervention and 8 control centres. Since June 2005, an early detection tool has been applied at age 14, 24, 36 and 45 months at the intervention centres. Children who met the intervention criteria received counselling intervention (personal advice to parents to prevent smoke exposure of the child, and/or referral to the general practitioner or asthma nurse). The primary outcome was asthma diagnosis at age 6 years. Secondary outcomes included frequency and severity of asthma symptoms, health-related quality of life, fractional exhaled nitric oxide and airway resistance at age 6 years. Analysis was according to the intention-to-treat principle. Data collection will be completed end 2011.

DISCUSSION

This study among preschool children provides insight into the effectiveness of early detection of asthma symptoms followed by a counselling intervention at preventive child health centres.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN15790308.

Intrauterine exposure to polycyclic aromatic hydrocarbons, fine particulate matter and early wheeze. Prospective birth cohort study in 4-year olds

The main goal of the study was to determine the relationship between prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) measured by PAH-DNA adducts in umbilical cord blood and early wheeze. The level of PAH-DNA adducts in the cord blood is assumed to reflect the cumulative dose of PAHs absorbed by the foetus over the prenatal period. The effect of prenatal PAH exposure on respiratory health measured by the incidence rate ratio (IRR) for the number of wheezing days in the subsequent 4 yr follow-up was adjusted for potential confounding factors such as personal prenatal exposure to fine particulate matter (PM(2.5)), environmental tobacco smoke (ETS), gender of child, maternal characteristics (age, education and atopy), parity and mould/dampness in the home. The study sample includes 339 newborns of non-smoking mothers 18-35 yr of age and free from chronic diseases, who were recruited from ambulatory prenatal clinics in the first or second trimester of pregnancy. The number of wheezing days during the first 2 yr of life was positively associated with prenatal level of PAH-DNA adducts (IRR = 1.69, 95%CI = 1.52-1.88), prenatal particulate matter (PM(2.5)) level dichotomized by the median (IRR = 1.38; 95%CI: 1.25-1.51), maternal atopy (IRR = 1.43; 95%CI: 1.29-1.58), mouldy/damp house (IRR = 1.43; 95%CI: 1.27-1.61). The level of maternal education and maternal age at delivery was inversely associated with the IRRs for wheeze. The significant association between frequency of wheeze and the level of prenatal environmental hazards (PAHs and PM(2.5)) was not observed at ages 3 or 4 yrs. Although the frequency of wheezing at ages 3 or 4 was no longer associated with prenatal exposure to PAHs and PM(2.5), its occurrence depended on the presence of wheezing in the first 2 yr of life, which nearly tripled the risk of wheezing in later life. In conclusion, the findings may suggest that driving force for early wheezing (<24 months of age) is different to those leading to later onset of wheeze. As we reported no synergistic effects between prenatal PAH (measured by PAH-DNA adducts) and PM(2.5) exposures on early wheeze, this suggests the two exposures may exert independent effects via different biological mechanism on wheeze.

Increasing body mass index from age 5 to 14 years predicts asthma among adolescents: evidence from a birth cohort study

BACKGROUND

Obesity and asthma are common disorders, and the prevalence of both has increased in recent decades. It has been suggested that increases in the prevalence of obesity might in part explain the increase in asthma prevalence. This study aims to examine the prospective association between change in body mass index (BMI) z-score between ages 5 and 14 years and asthma symptoms at 14 years.

METHODS

Data was taken from the Mater University Study of Pregnancy and its outcomes (MUSP), a birth cohort of 7223 mothers and children started in Brisbane (Australia) in 1981. BMI was measured at age 5 and 14 years. Asthma was assessed from maternal reports of symptoms at age 5 and 14 years. In this study analyses were conducted on 2911 participants who had information on BMI and asthma at both ages.

RESULTS

BMI z-score at age 14 and the change in BMI z-score from age 5 to 14-years were positively associated with asthma symptoms at age 14 years, whereas BMI z-score at age 5 was not associated with asthma at age 14. Adjustment for a range of early-life exposures did not substantially alter these findings. The association between change in BMI z-score with asthma symptoms at 14 years appeared stronger for male subjects compared with female subjects but there was no statistical evidence for a sex difference (P=0.36).

CONCLUSIONS

Increase in BMI z-score between age 5 and 14 years is associated with increased risk of asthma symptoms in adolescence.

The influence of maternal respiratory infections during pregnancy on infant lung function

INTRODUCTION

We studied whether maternal respiratory infections during pregnancy adversely influence lung growth and development of the offspring, resulting in poor early life lung function.

METHODS

Infants were participants of the Wheezing Illnesses Study Leidsche Rijn (WHISTLER). Lung function measurements (single occlusion technique) were performed during natural sleep. Questionnaire data were used to obtain information on maternal respiratory infections during pregnancy. Multivariate analysis was conducted to assess the relationship between maternal respiratory infections during pregnancy and resistance and compliance of the respiratory system, adjusting for potential confounding variables.

RESULTS

Lower values of compliance (Crs) were found in infants of mothers with respiratory infections during pregnancy; Crs fell by 5.5% (P = 0.031). The difference in Crs between infants of mothers with and without respiratory infections during pregnancy remained unchanged and statistically significant after adjusting for potential confounding variables. The more respiratory infections the mother experienced during pregnancy, the lower the value of Crs was in her offspring (P for trend = 0.016). Using Crs corrected for body weight the relationship with maternal infections was non-significant, however still showing a trend.

CONCLUSIONS

The results of this study may indicate that mothers who experience respiratory infections during pregnancy have newborns with lower compliance of the respiratory system.

Determinants of health care utilization for respiratory symptoms in the first year of life

OBJECTIVE

Health care utilization for respiratory symptoms is very common in infancy. Little is known about the determinants of visiting a physician for such complaints in infants. We investigated which factors determine the likelihood of visiting a physician for respiratory symptoms in the first year of life of their offspring.

PATIENTS AND METHODS

Infants were participants of the ongoing Wheezing Illnesses Study Leidsche Rijn (WHISTLER), a prospective birth cohort study on respiratory illnesses. Parental reports on respiratory symptoms and possible risk factors were assessed by daily questionnaires. Physician diagnosed respiratory symptoms were classified in medical records using the International Classification of Primary Care. Outcome was defined as a having a child visit a general practitioner for respiratory symptoms in the first year of life. Logistic regression was used to study the likelihood of outcome (yes/no) as a function of putative predictors.

RESULTS

Forty-seven percent of the infants visited a physician for respiratory symptoms in the first year of life. Every extra week of respiratory symptoms was associated with a 4.3% higher chance (odds ratio [OR], 1.043; 95% confidence interval [CI], 1.022-1.065) of visiting a physician. Furthermore, the chance was higher in boys (OR, 1.5; 95% CI, 1.1-2.1), children attending day care (OR, 1.9; 95% CI, 1.2-3.0), children with nonwhite mothers (OR, 1.9; 95% CI, 1.1-3.2), and children whose mother had supplementary health care insurance (OR, 1.7; 95% CI, 1.1-2.7). Findings were similar within the subgroup of children with serious respiratory symptoms (>median: 46 d/yr), but in that group parental age over 30 also determined physician visits (OR, 3.8; 95% CI, 1.6-8.9).

CONCLUSIONS

Child and parent characteristics, besides complaints per se, play an important role in health care utilization for respiratory illnesses in infancy.

Consumption of organic foods and risk of atopic disease during the first 2 years of life in the Netherlands

We prospectively investigated whether organic food consumption by infants was associated with developing atopic manifestations in the first 2 years of life. The KOALA Birth Cohort Study in the Netherlands (n 2764) measured organic food consumption, eczema and wheeze in infants until age 2 years using repeated questionnaires. Diet was defined as conventional ( 90 % organic). Venous blood samples taken from 815 infants at 2 years of age were analysed for total and specific IgE. Multivariate logistic regression models were fitted to control for potential confounding factors. Eczema was present in 32 % of infants, recurrent wheeze in 11 % and prolonged wheezing in 5 %. At 2 years of age, 27 % of children were sensitised against at least one allergen. Of all the children, 10 % had consumed a moderately organic diet and 6 % a strictly organic diet. Consumption of organic dairy products was associated with lower eczema risk (OR 0.64 (95 % CI 0.44, 0.93)), but there was no association of organic meat, fruit, vegetables or eggs, or the proportion of organic products within the total diet with the development of eczema, wheeze or atopic sensitisation. Further studies to substantiate these results are warranted.

Comparison of clinically diagnosed asthma with parental assessment of children's asthma in a questionnaire

Epidemiological evaluations of the prevalence of asthma are usually based on written questionnaires (WQs) in combination with validation by clinical investigation. In the present investigation, we compared parental assessment of asthma among their preschool children in response to a WQ with the corresponding medical records in the same region. An International Study of Asthma and Allergies in Childhood (ISAAC)-based WQ was answered by 75% of the parents of 6295 children aged 1-6 yr. Clinically diagnosed asthma, recorded in connection with admissions to the hospital or a visit to any of the outpatient clinics in the same region, were analysed in parallel. Finally, a complementary WQ was sent to the parents of children identified as asthmatic by either or both of this approaches. In response to the WQ 5.9% were claimed to suffer from asthma diagnosed by a doctor. According to the medical records, the prevalence of clinically diagnosed asthma was 4.9%. The estimated prevalence among children requiring treatment for their asthma was 4.4%. The sensitivity of the WQ was 77%, the specificity 97.5%. In the 1-2 yr age group the sensitivity was only 22%. This WQ was able to identify 54% of the children with a medical record of asthma. Forty percent of the children claimed by their parents to be asthmatic had no medical record of asthma. An ISAAC-based parentally completed WQ provided an acceptable estimation of the prevalence of asthma in children 2-6 yr of age, although only half of the individual patients identified in this manner are the same as those identified clinically.

Early life exposure to antibiotics and the subsequent development of eczema, wheeze, and allergic sensitization in the first 2 years of life: the KOALA Birth Cohort Study

OBJECTIVES

Antibiotic exposure in early life may be associated with atopic disease development either by interfering with bacterial commensal flora or by modifying the course of bacterial infections. We evaluated early life exposure to antibiotics and the subsequent development of eczema, wheeze, and allergic sensitization in infancy.

METHODS

Information on antibiotic use in the first 6 months and eczema and wheeze until age 2 was collected by repeated questionnaires in 2764 families participating in the KOALA (Child, Parent and Health: Lifestyle and Genetic Constitution [in Dutch]) Birth Cohort Study in The Netherlands. Antibiotic intake was evaluated both as maternal antibiotic use during breastfeeding and infant oral medication. Venous blood samples taken from 815 infants at 2 years of age were analyzed for total and specific immunoglobulin E against common food and inhalant allergens using a radioallergosorbent test. Multivariate logistic regression analysis was used to adjust for confounding factors.

RESULTS

During the first 2 years, eczema was present in 32% of all infants, recurrent wheeze in 11%, and prolonged wheezing in 5%. At 2 years old, 27% of children were sensitized against > or = 1 allergen. At 6 months old, 11% had been exposed to antibiotics through breast milk and 20% directly through medication. The risk for recurrent wheeze, and prolonged wheeze was higher in infants directly exposed to antibiotics through medication, also after excluding from the analyses children who wheezed in the same period as an antibiotic had been used (avoiding reverse causation). Antibiotic use through breastfeeding was associated with recurrent wheeze, but prolonged wheeze was not. Eczema and sensitization were not associated with antibiotic exposure.

CONCLUSIONS

We demonstrated that early antibiotic use preceded the manifestation of wheeze but not eczema or allergic sensitization during the first 2 years of life. Different biological mechanisms may underlie the etiology of wheeze compared with eczema or sensitization. Antibiotic exposure through breastfeeding enhanced the risk for recurrent wheeze, but this needs further confirmation.

Perinatal risk factors for sensitization, atopic dermatitis and wheezing during the first year of life (PIPO study)

OBJECTIVE

To evaluate the influence of perinatal environmental factors on early sensitization, atopic dermatitis and wheezing during the first year.

METHODS

Information on pregnancy-related factors, parental atopic history, environmental factors and the clinical course of the infant until age one was gathered by questionnaires, as part of a prospective birth cohort study (Prospective study on the Influence of Perinatal factors on the Occurrence of asthma and allergies [PIPO-study]). Quantification of total and specific IgE was performed in 810 children and their parents.

RESULTS

Early sensitization was found in 107/810 (13%) of the infants. Multiple regression analysis showed that specific IgE in fathers was a risk factor for early sensitization in their daughters (adjusted odds ratios (OR(adj)) 2.21 (95% confidence interval (CI) 1.10-4.49); P=0.03), whereas in boys, day care attendance was shown to be protective for early sensitization (OR(adj) 0.38 (95% CI 0.20-0.71); P=0.001). Atopic dermatitis occurred in 195/792 infants (25%). Specific IgE in the mother (OR(adj) 1.52 (95% CI 1.06-2.19); P=0.02) and in the infant (OR(adj) 4.20 (95% CI 2.63-6.68); P<0.001) were both risk factors for the occurence of atopic dermatitis, whereas postnatal exposure to cats was negatively associated with atopic dermatitis (OR(adj) 0.68 (0.47-0.97); P=0.03). Postnatal exposure to cigarette smoke (OR(adj) 3.31 (95% CI 1.79-6.09); P<0.001) and day care attendance (OR(adj) 1.96 (95% CI 1.18-3.23); P=0.009) were significantly associated with early wheezing, which occurred in 25% (197/795) of the infants.

CONCLUSION

The effect of paternal sensitization and day care attendance on sensitization is gender dependent. Maternal sensitization predisposes for atopic dermatitis, whereas postnatal exposure to cats had a protective effect.

Feasibility and variability of neonatal and infant lung function measurement using the single occlusion technique

INTRODUCTION

For possible use as a predictor of wheezing illnesses in routine care, we evaluated the feasibility and variability of measurement of passive respiratory mechanics in a large, open population of healthy neonates and infants.

METHODS

As part of the ongoing Wheezing Illnesses Study Leidsche Rijn, respiratory compliance (Crs), respiratory resistance (Rrs), and time constant (taurs) were measured during natural sleep in 450 healthy term neonates and infants using the single-occlusion technique (SOT). Interobserver and intraobserver variability of data sampling and the subsequent selection and analysis of occlusions as well as intra-measurement variability were examined.

RESULTS

Technically acceptable lung function measurements could be performed in 328 infants (73%). Low intraobserver and interobserver variability was found for both data sampling (intraclass correlation coefficient [ICC] > or = 0.87) and for selection and analysis of occlusions (ICC > or = 0.99). Intra-measurement variability was low, with a mean intra-measurement coefficients of variation for Crs, Rrs, and taurs of 8.5%, 10.4%, and 15.4%, respectively. Averaging three or more occlusions resulted in stable values of Crs, Rrs, and taurs.

CONCLUSION

Results of this study indicate that feasibility and variability of lung function testing using the SOT is acceptable for use in large populations of healthy neonates and infants in routine care.

The effect of pet ownership on the risk of allergic sensitisation and bronchial asthma

An increasing volume of evidence suggests that early contact of children with the allergens of furred pets (especially those produced by cats) may determine a lower risk of developing allergic sensitisation to these materials. A possible explanation of this data is that an early inhalation of high levels of the major cat allergen Fel d 1 induces the production of IgG and IgG4 antibodies with a "protective" effect. Other authors have shown that the prevalence of allergic sensitisation to cats, in adults, is reduced in those patients exposed to the lowest and highest levels of the allergens. On the contrary, the risk of developing sensitisation to cats is significantly higher when the patients were exposed to intermediate levels of Fel d 1. Moreover, epidemiological studies have demonstrated a relatively low prevalence of cat allergy (about 10%) in some countries where rates of cat ownership are high. This data confirms the role of indirect exposure to pet allergens in inducing allergic sensitisation. Clothes of pet owners have been indicated as the carriers for the dispersal of these allergens in pet-free environments. However, it is important to point out that exposure of highly sensitised patients to relevant amounts of pet allergens (such as in a pet shows/shops) may determine a dramatic exacerbation of nasal and/or bronchial symptoms.

Asthma and internalizing behavior problems in adolescence: a longitudinal study

OBJECTIVE

Clinical studies of asthmatic children have found an association between lung disease and internalizing behavior problems. The causal direction of this association is, however, unclear. This article examines the nature of the relationship between behavior and asthma problems in childhood and adolescence.

METHODS

Data were analyzed on 5135 children from the Mater University Study of Pregnancy and its outcomes (MUSP), a large birth cohort of mothers and children started in Brisbane, Australia, in 1981. Lung disease was measured from maternal reports of asthma/bronchitis when the children were aged 5 and maternal reports of asthma symptoms when the children were aged 14. Symptoms of internalizing behaviors were obtained by maternal reports (Child Behavior Checklist) at 5 years and by maternal and children's reports at 14 years (Child Behavior Checklist and Youth Self Report).

RESULTS

Although there was no association between prevalence of asthma and externalizing symptoms, asthma and internalizing symptoms were significantly associated in cross-sectional analyses at 5 and 14 years. In prospective analyses, after excluding children with asthma at 5 years, internalizing symptoms at age 5 were not associated with the development of asthma symptoms at age 14. After excluding children with internalizing symptoms at 5 years, those who had asthma at 5 years had greater odds of developing internalizing symptoms at age 14.

CONCLUSION

Children who have asthma/bronchitis by the age of 5 are at greater risk of having internalizing behavior problems in adolescence.

The Wheezing Illnesses Study Leidsche Rijn (WHISTLER): rationale and design

The Wheezing Illnesses Study Leidsche Rijn (WHISTLER) was initiated in December 2001 as a single-centre prospective birth cohort study and will include a population-based sample of at least 2000 healthy newborns. The aims of WHISTLER are to investigate determinants for wheezing illnesses (including neonatal lung function, viral infections, asthma-susceptibility genes and endotoxin exposure) and to derive a comprehensive risk score, that is appropriate for use in primary health care and allows for efficient planning of early preventive strategies. Baseline examination includes a questionnaire evaluating known risk factors for wheezing illnesses; anthropometric measurements; measurements of infant and parental lung function; and sampling of infant and parental DNA. Participants will be followed for respiratory events using data from a daily respiratory symptom questionnaire; visits to the general practitioner (primary health care visits, drugs prescriptions and hospital referral); viral sampling during wheezing episodes; and house dust sampling. Based on actual neonatal care practice and embedded in a larger epidemiological study, the Utrecht Health Project, WHISTLER will provide an unique framework to address issues in childhood respiratory disease that are currently insufficiently understood. In particular, WHISTLER will provide a well-balanced view on the prognostic power of neonatal lung function and genetic and environmental factors (including viral infections and endotoxin exposure) to predict wheezing illnesses from birth to young adulthood and beyond. In the scope of prevention, WHISTLER is expected to support the design of solid based prevention measures to reduce respiratory morbidity, mortality and associated costs, and to improve quality of life.

No epidemiological evidence for infant vaccinations to cause allergic disease

CONTEXT

The prevalence of allergic diseases has increased considerably over the last decades. The hygiene hypothesis has emerged, linking reduced microbial exposure and infections early in life with the development of allergic diseases. Especially some of currently available non-replicating infant vaccines are unlikely to mimic a natural infection-mediated immune response that protects against the development of allergic diseases. Moreover, several studies suggested infant vaccinations to increase the risk of allergic diseases.

OBJECTIVE

To determine whether infant vaccinations increase the risk of developing allergic disease.

DATA SOURCES

We searched MEDLINE from 1966 to March 2003 and bibliography lists from retrieved articles, and consulted experts in the field to identify all articles relating vaccination to allergy.

STUDY SELECTION AND DATA EXTRACTION

We selected epidemiological studies with original data on the correlation between vaccination with diphtheria, pertussis, tetanus (DPT), measles, mumps, rubella (MMR) and Bacillus Calmette-Guérin (BCG) vaccine in infancy and the development of allergic diseases, and assessed their quality and validity.

DATA SYNTHESIS

Methodological design and quality varied considerably between the studies we reviewed. Many studies did not address possible confounders, such as the presence of lifestyle factors, leaving them prone to bias. The studies that offer the stronger evidence, including the only randomized controlled trial at issue published to date, indicate that the infant vaccinations we investigated do not increase the risk of developing allergic disease. Furthermore, BCG does not seem to reduce the risk of allergies.

CONCLUSIONS

The reviewed epidemiological evidence indicates that, although possibly not contributing to optimal stimulation of the immune system in infancy, current infant vaccines do not cause allergic diseases.

Influence of male sex and parental allergic disease on childhood wheezing: role of interactions

BACKGROUND

Boys have been reported to be more susceptible to childhood wheezing, whereas girls are more susceptible later in life. This difference might be related to both genetic and environmental factors.

OBJECTIVE

To investigate the influence of male sex and parental allergic disease on the development of childhood wheezing.

METHODS

Infants (n=4089) born in Stockholm were recruited in a prospective study, BAMSE. Data on parental allergic diseases were obtained from questionnaires answered at the children's birth and on symptoms of wheezing at 1, 2 and 4 years of age. Sensitization to inhalant allergens and lung function was investigated at the age of 4 years.

RESULTS

Children were classified as having recurrent, transient (n=266), early-onset persistent (n=319) and late-onset wheezing (n=195). Boys were over-represented in all groups of wheezing (odds ratio, OR=1.4-1.5) and both maternal and paternal allergic disease was of importance for the wheezing outcomes. A dominating influence from maternal allergic disease was only seen in children with persistent wheezing. An interaction exceeding additivity was found between male sex and parental allergic disease, particularly in children with persistent wheezing (OR=2.9 and 95% confidence interval, CI 95% 2.1-4.0 for boys with any parental history vs. OR=1.4, CI 95% 1.0-2.1 for girls). Interaction between male sex and parental allergic disease was also observed in children who wheezed at the age of 4 years and were sensitized to inhalant allergens.

CONCLUSION

Our data suggest an interaction between male sex and parental allergic disease in childhood wheezing, which may represent a sex-specific genetic influence.

Value of a shortened questionnaire in the description of asthma in 10-12-year-old pupils

Asthma is a common and severe chronic disease in children influencing their quality of life and functioning at school. A 5-item asthma-screening instrument was developed and tested in 1052 children aged 10-12 years. Questionnaires were completed by parents and children separately and data were compared. Children reported less to be diagnosed by a medical doctor as having asthma compared with their parents, although children reported more to have certain asthma symptoms. No difference in prevalence of asthma was found between children and parents' answers. The absolute agreement for the scale was 92% and a good kappa agreement was found. Recoding the "don't know"-answers in "no"-answers resulted in a 4% misclassification. The short 5-item asthma screening tool can be valuable in the categorization of a subgroup of children likely to suffer from asthma in a survey. Recoding 'don't know'-answers to 'no'-answers is justified in large samples

Early respiratory and skin symptoms in relation to ethnic background: the importance of socioeconomic status; the PIAMA study

AIMS

To evaluate ethnic differences in the prevalence of respiratory and skin symptoms in the first two years of life.

METHODS

A total of 4146 children participated in the Prevention and Incidence of Asthma and Mite Allergy (PIAMA) study. Parents completed questionnaires on respiratory and skin symptoms, ethnic background, and other potential confounders during pregnancy, and at 3 months, 1 year, and 2 years of age.

RESULTS

In the first year, "non-Dutch" children (compared with "Dutch" children) had a higher prevalence of runny nose with itchy/watery eyes (11.0% versus 5.0%). In the second year, a higher prevalence of wheeze at least once (26.7% versus 18.5%), night cough without a cold (24.6% versus 15.5%), runny nose without a cold (34.1% versus 21.3%), and runny nose with itchy/watery eyes (13.7% versus 4.6%) was found. Adjustment for various confounders, especially adjustment for socioeconomic factors, reduced most associations between ethnicity and respiratory symptoms. Only runny nose with itchy/watery eyes in the second year of life was independently associated with non-Dutch ethnicity (adjusted odds ratio 2.89, 95% CI 1.3-6.4).

CONCLUSIONS

Non-Dutch children more often had respiratory symptoms in the first two years of life than Dutch children. This could largely be explained by differences in socioeconomic status. Follow up of the cohort will determine whether this higher prevalence of respiratory symptoms in children with non-Dutch ethnicity represents an increased risk of developing allergic disease rather than non-specific or infection related respiratory symptoms.

Preventive measures and their effects. Results from cohort studies

The prevalence of asthma and atopic diseases continues to rise. Genetic factors alone cannot explain this rapid rise and the immunological mechanisms involved are insufficiently explained to allow direct intervention on a population-wide scale. Long-term observational birth cohort studies have provided data on which primary prevention studies are based. This review discusses the "who", "how", "when" and "what" of primary prevention and the experiences to date in prospective intervention cohort studies.

Placebo-controlled trial of house dust mite-impermeable mattress covers: effect on symptoms in early childhood

We investigated the effect of house dust mite (HDM)-allergen avoidance on the development of respiratory symptoms, atopic dermatitis, and atopic sensitization by performing a double blind, placebo-controlled trial. In total, 1,282 allergic pregnant women were selected (416 received HDM allergen-impermeable mattress covers for the parents' and child's mattress in the third trimester of pregnancy [active], 394 received placebo covers, 472 received no intervention). Data on allergen exposure, clinical symptoms, and immunoglobulin E were collected prospectively. The prevalence of night cough without a cold in the second year of life was lower in the group with active covers compared with the group with placebo covers (adjusted odds ratio 0.65; 95% confidence interval 0.4-1.0). No effect of the intervention was seen on other respiratory symptoms, atopic dermatitis, and total and specific immunoglobulin E. It can be concluded that application of HDM-impermeable mattress covers on the child's and parents' beds reduced night cough, but not other respiratory symptoms, atopic dermatitis, and atopic sensitization in the first 2 years of life. Follow-up will determine the long-term effect of the intervention on the development of atopic disease.