Maternal age of menarche is not associated with asthma or atopy in prepubertal children

Early menarche predicts incidence of asthma in early adulthood

The present study explores the effect of age at menarche on the incidence of asthma during early adulthood. The analysis was based on Canadian girls followed up from 8-11 to 18-21 years of age during the first 6 cycles (1994-2005) of the National Longitudinal Survey of Children and Youth. Early menarche was defined as 1 standard deviation less than the average age at menarche. Asthma occurrence after menarche was measured as asthma that was diagnosed by a health care professional. The authors used logistic regression to investigate the association between early menarche and incidence of asthma, adjusting for possible confounders. A total of 1,176 girls weighted to represent 352,345 Canadian girls were analyzed. The incidence of asthma after menarche was 11.2% (95% confidence interval: 8.3, 14.0). The onset of early menarche (<11.56 years of age) predicted postmenarcheal incidence of asthma; girls who matured early had more than twice the risk of developing asthma during early adulthood than did girls who matured at an average age (odds ratio, 2.34, 95% confidence interval: 1.19, 4.59). The present study provides partial insight into the worldwide rapid increase in asthma rates that coincides with the declining trends in menarcheal timing. Further studies within different contexts are warranted to assess the generalizability of these Canadian findings.

Swimming pool attendance, asthma, allergies, and lung function in the Avon Longitudinal Study of Parents and Children cohort

RATIONALE

Cross-sectional studies have reported inconsistent findings for the association between recreational swimming pool attendance and asthma and allergic diseases in childhood.

OBJECTIVES

To examine whether swimming in infancy and childhood was associated with asthma and allergic symptoms at age 7 and 10 years in a UK longitudinal population-based birth cohort, the Avon Longitudinal Study of Parents and Children.

METHODS

Data on swimming were collected by questionnaire at 6, 18, 38, 42, 57, 65, and 81 months. Data on rhinitis, wheezing, asthma, eczema, hay fever, asthma medication, and potential confounders were collected through questionnaires at 7 and 10 years. Spirometry and skin prick testing were performed at 7 to 8 years. Data for analysis were available for 5,738 children.

MEASUREMENTS AND MAIN RESULTS

At age 7 years, more than 50% of the children swam once per week or more. Swimming frequency did not increase the risk of any evaluated symptom, either overall or in atopic children. Children with a high versus low cumulative swimming pool attendance from birth to 7 years had an odds ratio of 0.88 (95% confidence interval, 0.56-1.38) and 0.50 (0.28-0.87), respectively, for ever and current asthma at 7 years, and a 0.20 (0.02-0.39) standard deviation increase in the forced midexpiratory flow. Children with asthma with a high versus low cumulative swimming had an odds ratio for current asthma at 10 years of 0.34 (0.14-0.80).

CONCLUSIONS

This first prospective longitudinal study suggests that swimming did not increase the risk of asthma or allergic symptoms in British children. Swimming was associated with increased lung function and lower risk of asthma symptoms, especially among children with preexisting respiratory conditions.

Prevalence and associated factors of allergic rhinitis and atopic dermatitis in children

Allergic disorders are the chronic diseases of greatest pediatric morbidity, affecting over 25 % of the pediatric population. Indeed, this situation has been referred to as an "allergic epidemic". In comparison with asthma, atopic dermatitis and allergic rhinitis have been less extensively investigated, although this does not mean that they should be regarded as minor disorders but rather as alterations that affect the quality of life of the patients and their families, which generate considerable direct and indirect costs. Despite an important research effort, the reason for this allergic epidemic is not well known. These are multifactor disorders without a single causal agent, in which the most important component is the genetic predisposition of the patient (atopy), modulated by environmental factors, exposure to allergens, infections and irritants, among others. A confounding element is the fact that the concept of allergic diseases encompasses phenotypes of rhinitis, atopic dermatitis or asthma in which no IgE-mediated atopic mechanism is demonstrated, and which can manifest in a way similar to true allergic phenotypes. Differentiation between the two is difficult to establish on the basis of self-administered questionnaires alone, in the absence of a precise etiological diagnosis. The present article reviews the numerous factors suggested to be responsible for the increase in allergic diseases recorded in the last few decades, and for the differences in prevalence observed among centres. For most of these factors the results published in the literature are contradictory, in some cases due to a lack of control of the associated interacting or confounding factors. Consensus exists for only some of these causal factors, such as the established parallelism between the increase in allergic diseases and the reduction in infectious processes on one hand, and the increase in particles generated by diesel fuel combustion on the other. In addition, the implicated factors could act differently (and in some cases even antagonically) upon atopy and on the different disease phenotypes, thereby complicating the study of these interactions even further.