Incidence Of Physician-diagnosed Asthma Research Articles

Early Life Factors Associated with Incidence of Physician-diagnosed Asthma in Preschool Children: Results from the Canadian Early Childhood Development Cohort Study

Background. Asthma is a common childhood illness. The objective of this study is to determine the incidence of physician-diagnosed asthma in preschool years and its relationship to host, prenatal and postnatal factors, early childhood factors, parental factors, household factors and demographic factors. Methods. The study sample was comprised of 8,499 infants and toddlers (<2 years at baseline) enrolled in the Canadian Early Childhood Development Study. Incidence of asthma was determined when the children were in preschool age (2 to 5 years). Results. The 4-year cumulative incidence at preschool age was 13.7% for physician-diagnosed asthma. History of early childhood wheezing before 2 years of age was a significant risk factor for incidence of asthma in preschool years (hazard ratio (HR): 2.32; 95% confidence interval (CI): 2.04–2.65). Factors that were protective for the development of asthma were breastfeeding more than 3 months (HR: 0.82; 95% CI: 0.69–0.97); history of nose or throat infection often in childhood (HR: 0.79; 95% CI: 0.67–0.93); early daycare attendance (HR: 0.85; 95% CI: 0.74–0.98); presence of two or more siblings at birth, (HR: 0.79; 95% CI: 0.64–0.97); and dwelling in rural non- central metropolitan areas (HR: 0.81; 95% CI: 0.69–0.95). Male sex, low birth weight, childhood allergy, single parent, maternal smoking during pregnancy, maternal medication use, parental atopy, and low SES at baseline were significant risk factors for the incidence of physician-diagnosed asthma in preschool years. Conclusion. This study emphasizes the role of wheezing in infant and toddler age on early onset of asthma during preschool years. The results also provide additional importance of early exposures to environmental factors such as early infections, daycare attendance, and rural environment in the development of proper immune dynamics to prevent asthma.

The Obstructive Lung Disease in Northern Sweden (OLIN) longitudinal paediatric study I – the first 10 years

Prospective studies of asthma and allergic conditions based on the general population are scarce. To summarize the methods and main results from a prospective study among school children. In 1996, a cohort of 3525 children aged 7/8 years in Northern Sweden were invited to a questionnaire survey using an expanded ISAAC protocol, and 97% participated. The cohort has been followed up yearly with high participation rate. Skin prick tests were conducted 1996, 2000 and 2006/2007. Allergens in dust from homes and schools have been analyzed. Sub samples have participated in interviews, lung function tests, bronchial hyper reactivity test, and analyses of IgE and IgG antibodies in serum. The prevalence of asthma was 6% at age 7-8 years and increased by age. The incidence of physician-diagnosed asthma after the age of 7-8 years was around 1/100/year. The prevalence of positive skin prick test increased from 21% at age 7-8 to 30% at age 11-12 years. Remission of allergic sensitization was rare, while asthma remission was 5% yearly. The main risk factor for asthma and allergic sensitization increased in importance with increasing age. Allergic and non-allergic asthma had different risk factor pattern. Environmental risk factors decreased in impact after the age of 7. Avoidance of pets at home did not protect from asthma or allergic sensitization. The study includes important sources of data for further longitudinal analyses that will contribute to the understanding of the development and the nature of asthma and allergic sensitization.

Reduced risk of physician‐diagnosed asthma among children dwelling in a farming environment

Living in a farm environment has been reported to be associated with lower prevalence of asthma, based on the results of cross-sectional studies. The objective of this longitudinal study was to determine whether living in a farm environment is associated with lower incidence of asthma among children. A total of 13 524 asthma-free children aged 0-11 years were drawn from the Cycle 1 (1994/1995) of the Canadian National Longitudinal Survey of Children and Youth (NLSCY). Subjects were categorized as dwelling in rural farming, rural non-farming and non-rural environments. Incidence of physician-diagnosed asthma was determined at Cycle 2 (1996/1997). Bootstrap logistic regression method was used to adjust for design effect in the NLSCY. The 2-year cumulative incidence of asthma was 2.3%, 5.3% and 5.7% among children living in farming, rural non-farming and non-rural environments, respectively. From the multivariate analysis with adjustment for important confounders, children from a farming environment had a reduced risk of asthma compared with children from rural non-farming environment with odds ratios (OR) of 0.22 (95% CI: 0.07-0.74) and 0.39 (95% CI: 0.24-0.65) for children with and without parental history of asthma, respectively. Children living in a non-rural environment with parental history of asthma had an increased risk of asthma incidence when compared with children living in rural non-farming environment (OR = 2.51, 95% CI: 1.56-4.05). This longitudinal study expands on observational study results which suggest a reduced risk of developing asthma associated with living in a farming environment.

The Use of Household Cleaning Sprays and Adult Asthma

Cleaning work and professional use of certain cleaning products have been associated with asthma, but respiratory effects of nonprofessional home cleaning have rarely been studied. To investigate the risk of new-onset asthma in relation to the use of common household cleaners. Within the follow-up of the European Community Respiratory Health Survey in 10 countries, we identified 3,503 persons doing the cleaning in their homes and who were free of asthma at baseline. Frequency of use of 15 types of cleaning products was obtained in a face-to-face interview at follow-up. We studied the incidence of asthma defined as physician diagnosis and as symptoms or medication usage at follow-up. Associations between asthma and the use of cleaning products were evaluated using multivariable Cox proportional hazards or log-binomial regression analysis. The use of cleaning sprays at least weekly (42% of participants) was associated with the incidence of asthma symptoms or medication (relative risk [RR], 1.49; 95% confidence interval [CI], 1.12-1.99) and wheeze (RR, 1.39; 95% CI, 1.06-1.80). The incidence of physician-diagnosed asthma was higher among those using sprays at least 4 days per week (RR, 2.11; 95% CI, 1.15-3.89). These associations were consistent for subgroups and not modified by atopy. Dose-response relationships (P < 0.05) were apparent for the frequency of use and the number of different sprays. Risks were predominantly found for the commonly used glass-cleaning, furniture, and air-refreshing sprays. Cleaning products not applied in spray form were not associated with asthma. Frequent use of common household cleaning sprays may be an important risk factor for adult asthma.

Vaccination and allergic disease: a birth cohort study.

We examined the effect of vaccination for diphtheria; polio; pertussis and tetanus; or measles, mumps, and rubella on the incidence of physician-diagnosed asthma and eczema. We used a previously established birth cohort in the West Midlands General Practice research database. We found an association between vaccination and the development of allergic disease; however, this association was present only among children with the fewest physician visits and can be explained by this factor. Our data suggest that currently recommended routine vaccinations are not a risk factor for asthma or eczema.

Effect of cat and dog ownership on sensitization and development of asthma among preteenage children.

An inverse relationship has been proposed between exposure to high quantities of cat allergen at home and both asthma and cat allergy. First- and second-grade children from Luleå, Kiruna, and Piteå, Sweden participated in an asthma questionnaire study (n = 3,431) and incidence was evaluated over the next 3 years. Skin testing was performed on the children in Luleå and Kiruna (n = 2,149). The strongest risk factor for incident cases of asthma was Type 1 allergy (relative risk [RR], 4.9 [2.9-8.4]), followed by a family history of asthma (RR, 2.83 [1.8-4.5]). Living with a cat was inversely related both to having a positive skin test to cat (RR, 0.62 [0.47-0.83]) and incidence of physician-diagnosed asthma (RR, 0.49 [0.28-0.83]). This effect on incident asthma was most pronounced among the children with a family history of asthma (RR, 0.25 [0.08-0.80]). The evidence also suggests that many of the children exposed to cats at home can develop an immune response that does not include immunoglobulin E. Weaker protective trends were seen with dog ownership. The traditional thinking that not owning cats can provide protection against developing allergy and asthma among those with a family history of allergy needs to be re-evaluated. In a community where cat sensitization was strongly associated with asthma, owning a cat was protective against both prevalent and incident asthma.

Incidence and remission of asthma in schoolchildren: report from the obstructive lung disease in northern Sweden studies.

An increasing prevalence of asthma has been reported worldwide as well as in Sweden. In 1996, the prevalence of asthma and type 1 allergy was investigated in a cohort of 3525 children 7 and 8 years old in 3 areas of northern Sweden. The aim of the present study was to estimate the incidence of asthma and to identify risk factors for incident cases over 1 year. The study started with a parental questionnaire, the International Study of Asthma and Allergies in Childhood questionnaire with additional questions, a skin prick test, and a validation study. The cohort was followed up after 1 year with the same questions. The response rate to the questionnaire was 97% in 1996, and 3339 children (97%) participated both in 1996 and 1997. The incidence of physician-diagnosed asthma was 0.9/100/year; of wheezing, 3.8/100/year; and of new frequent or daily users of asthma medicines, 1.1/100/year. There was no difference by sex. The risk factor pattern based on incident cases of asthma was different from that based on prevalent cases. Significant risk factors for incident asthma were a positive skin test (odds ratio [OR]: 9.3; 95% confidence interval [CI]: 3.8-22.7); low birth weight (OR: 7.4; 95% CI: 2.2-24.5); and family history of asthma (OR: 2.6; 95% CI: 1.1-6.3). Having or having had pets at home was associated with a decreased risk for asthma and wheezing based on prevalent cases, although it was associated with an increased risk for incidence of wheezing (OR: 2.9; 95% CI: 1.3-6.2). Remission of asthma, which was reported by 10% of the children with current asthma during 1 year, was associated with a negative skin test. The incidence of asthma at the age of 8 years was high, but remission was also common. Important risk factors for the development of asthma at this age were type 1 allergy, low birth weight, and family history of asthma. Furthermore, the results suggest that in a region where sensitivity to domestic animals is a strong risk factor for asthma, the presence of pets in the home may have different effects in early childhood compared with later in childhood.