Risk Factors For Wheezing Research Articles

Asthmatic Symptoms among Pupils in Relation to Winter Indoor and Outdoor Air Pollution in Schools in Taiyuan, China

BackgroundThere are few studies on associations between children’s respiratory heath and air pollution in schools in China. The industrial development and increased traffic may affect the indoor exposure to air pollutants in school environment. Moreover, there is a need to study respiratory effects of environmental tobacco smoke (ETS) and emissions from new building materials in homes in China.ObjectivesWe studied the associations between pupils’ asthmatic symptoms and indoor and outdoor air pollution in schools, as well as selected home exposures, in a coal-burning city in north China.MethodsA questionnaire survey was administered to pupils (11–15 years of age) in 10 schools in urban Taiyuan, collecting data on respiratory health and selected home environmental factors. Indoor and outdoor school air pollutants and climate factors were measured in winter.ResultsA total of 1,993 pupils (90.2%) participated; 1.8% had cumulative asthma, 8.4% wheezing, 29.8% had daytime attacks of breathlessness. The indoor average concentrations of sulfur dioxide, nitrogen dioxide, ozone, and formaldehyde by class were 264.8, 39.4, 10.1, and 2.3 μg/m3, respectively. Outdoor levels were two to three times higher. Controlling for possible confounders, either wheeze or daytime or nocturnal attacks of breathlessness were positively associated with SO2, NO2, or formaldehyde. In addition, ETS and new furniture at home were risk factors for wheeze, daytime breathlessness, and respiratory infections.ConclusionsIndoor chemical air pollutants of mainly outdoor origin could be risk factors for pupils’ respiratory symptoms at school, and home exposure to ETS and chemical emissions from new furniture could affect pupils’ respiratory health.

Exposure to dust mite allergen and endotoxin in early life and asthma and atopy in childhood

There has been no longitudinal study of the relation between concurrent exposure to dust mite allergen and endotoxin in early life and asthma and atopy at school age. To examine the relation between exposure to dust mite allergen and endotoxin at age 2 to 3 months and asthma, wheeze, and atopy in high-risk children. Birth cohort study of 440 children with parental history of atopy in the Boston metropolitan area. In multivariate analyses, early exposure to high levels of dust mite allergen (> or =10 microg/g) was associated with increased risks of asthma at age 7 years (odds ratio [OR], 3.0; 95% CI, 1.1-7.9) and late-onset wheeze (OR, 5.0; 95% CI, 1.5-16.4). Exposure to endotoxin levels above the lowest quartile at age 2 to 3 months was associated with reduced odds of atopy at school age (OR, 0.5; 95% CI, 0.2-0.9). In contrast with its inverse association with atopy, endotoxin exposure in early life was associated with an increased risk of any wheeze between ages 1 and 7 years that did not change significantly with time (hazard ratio for each quartile increment in endotoxin levels, 1.23; 95% CI, 1.07-1.43). Among children at risk of atopy, early exposure to high levels of dust mite allergen is associated with increased risks of asthma and late-onset wheeze. In these children, endotoxin exposure is associated with a reduced risk of atopy but an increased risk of wheeze. Early endotoxin exposure may be a protective factor against atopy but a risk factor for wheeze in high-risk children.

The Prenatal Use of Antibiotics and the Development of Allergic Disease in One Year Old Infants. A Preliminary Study

Recent research has suggested that the protective effect of natural infections may be due to their influence on the development of the immune system in early life. The purpose of the study was to determine whether maternal use of antibiotics during pregnancy is a risk factor for wheezing and allergy in early infancy. Nonsmoking women, aged 18-35 years, were enrolled in 2000/2001 from prenatal clinics during the second or third trimester of pregnancy. After delivery, newborns were followed-up every three months over one year and trained interviewers conducted a standardized interview with mothers on infants' health at each visit held every three-month. In total, 102 infants were followed over a one-year period and questionnaires on the use of various medications during pregnancy and potential risk factors for allergy and asthma were completed. Relative risk for persistent wheezing (9+ days over the follow-up) adjusted for potential confounders was significantly associated with the duration of antibiotic therapy, however, it was significant only if the antibiotic treatment took place in the second and the third trimester. The adjusted relative risk was increasing by 14% with each day of using antibiotics compared with the reference group (RR = 1.14; 95% CI: 1.01-1.27). When usage of antibiotics was regarded as a dichotomous variable in the logistic model (cut-off point at 5 days), the estimated adjusted risk for persistent wheezing was 4.42 (95% CI: 1.05-18.8). The risk for hay fever due to exposure to antibiotics was 2.65 (95% CI: 1.03-6.81) and a corresponding estimate for eczema was 2.30 (95% CI: 0.91-5.80). The study suggests that maternal use of antibiotics during pregnancy may prove to be a risk factor for persistent wheezing and development of allergy in early infancy.

A Comparison of Risk Factors for Wheeze and Recurrent Cough in Preschool Children

In a study of 2,978 Danish children aged 5 years from two suburban counties of Copenhagen, carried out in 1998, the authors compared risk factor profiles for wheeze and recurrent cough without wheeze by using polytomous logistic regression to clarify whether the two conditions are likely to have the same etiology. Data were obtained 1) by a mailed parental questionnaire (International Study of Asthma and Allergies in Childhood questions and supplementary questions on cough, sociodemography, perinatal factors, and environmental exposure); 2) through general practitioners (familial allergic disease); and 3) from the National Medical Birth Register (birth weight). Wheeze (WH) was defined as more than one episode of wheeze within the last 12 months (irrespective of cough status) and recurrent cough without WH (RC) as cough occurring outside colds and usually lasting for periods of more than 1 week in children with no more than one attack of wheeze within the last 12 months. Risk factors for comparison were selected as those that, after repeated stepwise logistic regression, remained significant for children with WH or RC. Significant differences were found for gender (p = 0.003), gestational age (p = 0.0002), maternal history of asthma (p = 0.0008), and standard of housing condition (p = 0.04)-all risk factors for WH but not RC. Results may suggest that the two conditions have different etiologies.

Bottle feeding in the bed or crib before sleep time and wheezing in early childhood.

Bottle feeding in the bed or crib before sleep time has been associated with an increased risk of wheezing in the first year of life. We examined whether bottle feeding in the bed or crib before sleep time in the first year of life is associated with wheezing in the first 5 years of life. In a prospective cohort study of 448 children with parental history of atopy followed from birth, we examined the relation between the number of bimonthly parental reports of bottle feeding in the bed or crib before sleep time in the first year of life (range: 0-6 reports) and parental report of wheezing in the first 5 years of life. Additional outcome measures included recurrent wheezing (> or =2 episodes of wheezing in the previous year) and asthma (physician-diagnosed asthma and > or =1 episode of wheezing in the previous year) at the age of 5 years. The risk of recurrent wheezing and asthma at 5 years of age increased significantly with each additional report of bottle feeding in the bed or crib before sleep time in the first year of life. The risk of wheezing between the ages of 1 and 5 years increased with each additional report of bottle feeding in the bed or crib before sleep time in the first year of life. As an example, a child whose parents reported bottle feeding in the bed or crib before sleep time on 3 occasions in the first year of life had 1.5 times higher risk of wheezing between the ages of 1 and 5 years than a child whose parents did not report bottle feeding in the bed or crib before sleep time in the first year of life (95% confidence interval for relative risk: 1.12-2.12). Among children with parental history of atopy, bottle feeding in the bed or crib before sleep time in the first year of life is a risk factor for recurrent wheezing and asthma at 5 years of age and a risk factor for wheezing between the ages of 1 and 5 years.

Risk factor associations with wheezing patterns in children followed longitudinally from birth to 3 ½ years

There is a paucity of detailed longitudinal data on wheeze in early childhood. Not all children who wheeze in early infancy will continue to wheeze into childhood and beyond. This study aims to investigate possible risk factors for different patterns of wheeze in the pre-school years. Study participants were part of the Avon Longitudinal Study of Parents and Children (ALSPAC). Maternal reports of child wheeze between birth and 6 months and again between 30 and 42 months were gathered prospectively. Children were categorized into early wheeze, persistent wheeze or late onset wheeze. A large number of risk factors were assessed for each wheezing phenotype using multivariable logistic regression models. Over 70% of children who wheezed in the first 6 months did not wheeze 3 years later. Wheezing between 0-6 months was independently associated with the presence of older siblings, male sex, delivery between April and December, bottle feeding, young maternal age, prenatal tobacco smoke exposure, atopy and parental history of asthma. From within this group of early wheezers, risk factors for wheeze that persisted beyond 6 months included pre-term delivery, young maternal age, living in rented local authority housing, atopy and a maternal (not paternal) history of asthma. Atopy and a family history of asthma emerged as the main predictors of wheeze that developed after 6 months of age. It is clear that a number of wheezing syndromes exist by 3(1/2) years, albeit with some degree of overlap. Detailed follow-up of this cohort is underway to determine whether risk factor associations determined in the first 3(1/2) years have long-term significance for the clinical entity termed 'asthma'.

Risk factors for adult onset wheeze: a case control study.

Risk factors associated with adult onset wheeze were examined in a case control study of subjects aged 39-45 yr derived from a community cohort of 2,056 asymptomatic children originally studied in 1964. Participants included 102 cases with adult onset wheeze (since age 15) and 217 controls with no wheeze. Logistic regression analysis was used to determine independent risk factors for wheeze among all cases and three subgroups: doctor diagnosed asthma (n = 24), wheeze with chronic cough and phlegm (n = 31), and other wheeze (n = 47). The risk of adult onset wheeze among all cases increased with low socioeconomic status (relative risk [RR] 2.36), current smoking (RR 2.01), positive atopic status (RR 3.28), and positive family history of atopic disease (RR 5.49). Gender was not related to the risk of wheezing. The pattern of significant independent risk factors differed between the subgroups of cases. Socioeconomic status was associated with cough and phlegm and other wheeze. Smoking habit was only related to cough and phlegm. Atopy was associated with doctor diagnosed asthma and cough and phlegm. Family history of atopic disease was related to all subgroups, suggesting that despite apparent heterogeneity in diagnostic labeling, concurrent symptoms, and other risk factors, the different forms of adult onset wheeze may share a common allergic basis.

Lower respiratory tract symptoms in Queensland schoolchildren: risk factors for wheeze, cough and diminished ventilatory function.

The occurrence of respiratory symptoms and abnormal lung function in children is known to be influenced by genetic and many environmental factors. The association between specific respiratory symptoms in children of school age and their parents has been examined. Respiratory symptoms and ventilatory function were recorded for 4549 schoolchildren in Queensland, Australia. The cumulative prevalence of wheezing was 23.1% of 8 year olds and 20.8% of 12 year olds, and the prevalence of wheezing within the previous 12 months was 13.9% and 10.5% respectively. A parental history of asthma or wheeze and hayfever was associated with wheeze in the child, but did not affect either the age of onset or frequency of episodes. A history of frequent cough in children who had never wheezed was associated with a parental history of frequent bronchitis, but less strongly with parental wheeze. These familial aggregations were not mediated by common exposure to cigarette smoke. Both a history of parental wheeze and maternal cigarette use were associated with a decrease in FEF25-75 in the child and these effects were additive. The association of specific symptoms (wheeze and cough without wheeze) in parent and offspring is interpreted as evidence for different mechanisms of familial transmission, which may be genetic.

Effect of cigarette tar content and smoking habits on respiratory symptoms in women.

Standardized respiratory disease questionnaires (ATS-DLD-78) were administered to 5,686 adult women. Risk factors were evaluated by logistic analysis that adjusted for multiple potential confounding factors. Among current smokers, the number of cigarettes smoked per day was consistently the strongest risk factor for chronic cough, chronic phlegm, wheeze, and dyspnea. The odds ratios for these symptoms in a smoker of 25 or more cigarettes per day relative to a smoker of 1--14 cigarettes per day were 4.74, 4.21, 2.05, and 3.71, respectively. Ex-smokers showed risks between those of current and never smokers. Cigarette tar content was a significant independent risk factor for chronic cough (p = 0.005) and of borderline significance for chronic phlegm (p = 0.077). High tar cigarette smokers in this population (average, 22 mg) had an odds ratio of 2.01 for chronic cough and 1.59 for chronic phlegm relative to low tar cigarette smokers (average, 7 mg). The effect of cigarette tar was linear and independent of cigarettes smoked per day. Smoke inhalation was a significant risk factor for chronic cough (p = 0.029) and for chronic phlegm (p = 0.038). Tar content and smoke inhalation were not significant risk factors for wheeze or dyspnea. Cigarette particulate content (tar) appears to be causally linked to cough and phlegm production., but the association of cigarette smoking and symptoms of wheeze and dyspnea may be more strongly related to the vapor phase of cigarette smoke.