Persistence of asthma symptoms during adolescence: role of obesity and age at the onset of puberty

A brief targeted review of susceptibility factors, environmental exposures, asthma incidence, and recommendations for future asthma incidence research

Relative to research on effects of environmental exposures on exacerbation of existing asthma, little research on incident asthma and environmental exposures has been conducted. However, this research is needed to better devise strategies for the prevention of asthma. The U.S. Environmental Protection Agency (EPA) and National Institute of Environmental Health Sciences held a conference in October 2004 to collaboratively discuss a future research agenda in this area. The first three articles in this mini-monograph summarize the discussion on potential putative environmental exposure; they include an overview of asthma and conclusions of the workshop participants with respect to public health actions that could currently be applied to the problem and research needs to better understand and control the induction and incidence of asthma, the potential role of indoor/outdoor air pollutants in the induction of asthma), and biologics in the induction of asthma. Susceptibility is a key concept in the U.S. EPA "Asthma Research Strategy" document and is associated with the U.S. EPA framework of protecting vulnerable populations from potentially harmful environmental exposures. Genetics, age, and lifestyle (obesity, diet) are major susceptibility factors in the induction of asthma and can interact with environmental exposures either synergistically or antagonistically. Therefore, in this fourth and last article we consider a number of "susceptibility factors" that potentially influence the asthmatic response to environmental exposures and propose a framework for developing research hypotheses regarding the effects of environmental exposures on asthma incidence and induction.

Association between leptin and asthma in adults

BACKGROUND

Leptin, a pro-inflammatory cytokine produced by adipose tissue, has previously been shown to be associated with asthma in children. We hypothesised that high serum leptin concentrations would also be associated with asthma in adults.

METHODS

The Third National Health and Nutrition Examination Survey is a cross sectional study that included fasting serum leptin concentrations and self-report of doctor diagnosed asthma. Data were analysed using multivariable logistic regression analysis.

RESULTS

Of 5876 participants, those with current asthma had a higher mean unadjusted leptin concentration than those who had never had asthma (geometric mean (SE) 9.2 (0.6) microg/l v 7.6 (0.2) microg/l; p = 0.02). After adjustment for triceps skinfold thickness and other covariates, the association between leptin and asthma appeared stronger in women than in men, and in premenopausal women than in postmenopausal women. Body mass index (BMI) was also associated with current asthma in women, but this association was not significantly affected by adjustment for leptin concentrations.

CONCLUSIONS

The results of this large population based study support the hypothesis that leptin is associated with asthma in women. In addition, while BMI also is related to asthma in women, this study does not support the suggestion that leptin contributes significantly to this association.

Asthma among rural Minnesota adolescents

This study examined the prevalence of and risk factors for wheezing and asthma in rural Minnesota adolescents. A survey querying about wheezing, asthma, farm residence, and other respiratory-related factors was administered to all 9th to 11th grade students (N = 13,490) in a stratified, random sample of high schools in rural Minnesota. Nearly one in 8 (12.6%) students reported ever-diagnosed asthma, and 9.2% reported current asthma. Students living on farms reported less wheezing and asthma than rural non-farm students. Obesity and smoking were associated with wheezing and asthma in all rural adolescents. Asthma rates increased with age among girls and may be largely accounted for by simultaneous increases in smoking rates. Despite the apparent protective effect of farm residence, asthma remains a significant public health issue among rural Minnesota adolescents.

Body mass index and physical activity in relation to asthma and atopic diseases in young adults

BACKGROUND

Obesity has been shown to increase the risk of asthma and wheezing. Conditioning exercise might decrease the asthma risk, and that could partly explain the association. The relation between obesity and allergic diseases is quite conflicting.

METHODS

The association between body mass index (BMI) and physician-diagnosed asthma, allergic rhinitis or conjunctivitis, atopic dermatitis, and self-reported wheezing was investigated in a questionnaire study among 10,667 Finnish first-year university students aged 18-25 years. Logistic regression was used to evaluate possible confounding by parental education, passive smoking at age 0-2, childhood residential environment, current and past smoking and leisure time physical activity index.

RESULTS

In men, there was a greater risk of asthma, but not wheezing with increasing BMI. Compared to those with BMI below 20, OR for male asthma was 1.98 (95% CI 1.11-3.52) in BMI category 20.0-22.4, 1.90 (95% CI 1.05-3.41) in BMI 22.5-24.9, and 3.5 (95% CI 1.63-7.64) in BMI > or = 27.5. Among women, the risks of asthma and wheezing were about two-fold among the overweight-obese subjects. Moderate leisure time physical activity was associated with lower risk of asthma in men (OR 0.62, 95% CI 0.62 (0.42-0.92), but not among women. The risk of allergic rhinoconjunctivitis and atopic dermatitis increased quite linearly with BMI among women but not men.

CONCLUSIONS

Low leisure time physical activity seems not to explain the greater risk of asthma among obese men and women. The quite linear association between BMI and both allergic rhinoconjunctivitis and wheezing among women suggests the independent effect of body fat on atopic diseases.

Asthma and body weight change: a 20-year prospective community study of young adults

OBJECTIVE

There is increasing evidence for an association between asthma and body weight change. The objectives of these analyses were to examine the temporal relationships of this association and to explore the role of childhood depression as an explanatory factor.

METHODS

Data were derived from six subsequent semistructured interviews on health habits and health conditions from a single-age community study of 591 young adults followed up between ages 20 and 40 years.

RESULTS

Cross-sectionally (over the whole study period), asthma was significantly associated with obesity (odds ratio=3.9 [95% confidence interval 1.2, 12.2]). Multivariate longitudinal analyses revealed that asthma was associated with increased later weight gain and later obesity among women after controlling for potentially confounding variables, whereas weight gain and obesity were not associated with later asthma. A secondary analysis showed that depressive symptoms during childhood were associated with adult obesity and asthma, partially explaining the asthma-obesity comorbidity.

CONCLUSION

This study encourages further research on mechanisms underlying the asthma-obesity comorbidity, particularly on shared psychosocial factors operating during critical periods in childhood and adolescence that may influence the development and persistence of both obesity and asthma during adulthood.

Asthma and activities of daily living

The provider's ability to judge the severity of a patient's illness is a vital part of the care of chronic disorders. In the treatment of asthma, it should extend beyond the objectively quantifiable measures of obstruction or inflammation. "Interference with activities of daily living" is a highly subjective assessment that may not allow quantitative comparisons, but it matters to the patient. Interventions aimed at lessening the burden of asthma on the daily life of the patient and his or her family may hold the key to improvement in a broader range of outcome measures.

Childhood asthma: breakthroughs and challenges

As we move forward, our goal is to control and eliminate asthma and other allergic disorders. This may come through broadly applied manipulation of environmental, dietary, and infectious risk factors, possibly during the perinatal period. Or we may learn to identify genetically susceptible children and to intervene with individualized genotype-specific treatment before the onset of disease. Maybe we'll learn how to block the mechanisms that give rise to chronic inflammation, or how to subdue Th2 activation. However, as the Swedish proverb says--Don't throw away the old bucket until you know whether the new one holds water. To continue using the old bucket, we have to fix the leaks. One approach to reducing asthma disparities is through traditional disease prevention stages. Primary prevention targets asthma incidence; secondary prevention mitigates established disease and involves disease detection, management, and control; and tertiary prevention is the reduction of complications caused by severe disease. Once causative factors at each level of disease prevention are understood, this knowledge can be translated into clinical practice and public health policy. We need reliable diagnostic criteria to provide correct treatment for infants and toddlers. This will require longitudinal cohort studies supported by assessment of pulmonary function and inflammatory markers. We must find ways to convince more physicians to embrace controller therapy for more severe disease, and to identify the patients with less severe disease who also require ongoing controller therapy. We need to close the gap between what we know and what we do in practice. We need to link basic research to healthcare delivery, and to gain acceptance and support from the intended recipients of new interventions. We need better strategies for improving adherence. We need accountability, foresight, and imagination.

Genetic pleiotropy between asthma and obesity in a community-based sample of twins

BACKGROUND

Asthma and obesity are common conditions that are strongly associated. This association might be due to shared genetic or environmental causes.

OBJECTIVE

We sought to determine whether a shared genetic cause is responsible for the association between asthma and obesity and to estimate the magnitude of shared genetic cause.

METHODS

The analyses were performed with 1001 monozygotic and 383 dizygotic same-sex twin pairs within the University of Washington Twin Registry. The presence of asthma was determined by self-report of a physician diagnosis of asthma, and body mass index (BMI) was calculated by using self-reported height and weight. Obesity was defined as a BMI of 30 or greater. The association between asthma and BMI was assessed by means of mixed-effects ordinal regression. Twin correlations examined the association of asthma and obesity. Univariate and bivariate structural equation models estimated the components of variance attributable to genetic and environmental effects.

RESULTS

A strong association between asthma and BMI was identified in the sample population (P < .001). Substantial heritability was detected for asthma (53%) and obesity (77%), which is indicative of additive genetic influences on each disorder. The best-fitting model of shared components of variance indicated that 8% of the genetic component of obesity is shared with asthma.

CONCLUSION

The covariation between obesity and asthma is predominantly caused by shared genetic risk factors for both conditions.

Obesity and asthma

Obesity is an important public health problem. An increasing body of data supports the hypothesis that obesity is a risk factor for asthma. These data include numerous large cross-sectional and prospective studies performed in adults, adolescents, and children throughout the world. With few exceptions, these studies indicate an increased relative risk of asthma in the obese and overweight and demonstrate that obesity antedates asthma. Obesity appears to be a particularly important issue for severe asthma. Studies showing improvements in asthma in subjects who lose weight, as well as studies showing that obese mice have innate airway hyperresponsiveness (AHR) as well as increased responses to certain asthma triggers also suggest a causal relationship between obesity and asthma. The mechanistic basis for this relationship has not been established. It may be that obesity and asthma share some common etiology, such as a common genetic predisposition, common effects of in utero conditions, or that obesity and asthma are both the result of some other predisposing factor such as physical activity or diet. However, there are also plausible biological mechanisms whereby obesity could be expected to either cause or worsen asthma. These include co-morbidities such as gastroesophageal reflux, complications from sleep-disordered breathing (SDB), breathing at low lung volume, chronic systemic inflammation, and endocrine factors, including adipokines and reproductive hormones. Understanding the mechanistic basis for the relationship between obesity and asthma may lead to new therapeutic strategies for treatment of this susceptible population.

An Increase in Bronchial Responsiveness Is Associated with Continuing or Restarting Smoking

RATIONALE

Bronchial responsiveness (BHR) has been found to be associated with smoking, atopy, and lower lung function in cross-sectional studies, but there is little information on determinants of change in adults.

OBJECTIVES

To analyze change in bronchial responsiveness in an international longitudinal community study.

METHODS

The study was performed in 3,993 participants in the European Community Respiratory Health Survey who had bronchial responsiveness measured in 1991-1993, when aged 20 to 44 yr, and in 1998-2002.

MEASUREMENTS

Bronchial responsiveness was assessed by methacholine challenge. Serum samples were tested for total IgE, and for specific IgE to four common allergens. Smoking information was obtained from detailed administered questionnaires. Change in bronchial responsiveness was analyzed by change in IgE sensitization, smoking, and lung function, with tests of interaction terms with age and sex.

MAIN RESULTS

Continuing and restarting smokers had increasing bronchial responsiveness, approximately equivalent to a mean reduction in PD20 of 0.68 and 0.75 doubling doses, respectively, over 10 yr, in addition to a small increase explained by decline in FEV1. No other risk factor for change in bronchial responsiveness was identified.

CONCLUSIONS

Smoking is a risk factor for increasing bronchial responsiveness over and above the effect of decreasing lung function. Neither baseline IgE sensitization nor change in sensitization was shown to be a risk factor for increasing BHR, the latter possibly due to little overall increase or decrease in sensitization.

Teenage asthma after severe early childhood wheezing: an 11-year prospective follow-up

The role of factors related to early wheezing and their associations with subsequent development of asthma are controversial. We reevaluated 81 children who had been prospectively followed up since hospitalization for wheezing at less than 2 years of age. The baseline data on characteristics of the children, family-related factors, and viral causes of wheezing were collected on entry into the study. At the median age of 12.3 years, current symptoms suggestive of asthma and allergy were recorded. As part of the clinical examination, an outdoor exercise challenge test and skin prick tests to common inhalant allergens were performed. Asthma, as indicated by current inhaled anti-inflammatory medication or repeated wheezing and positive result in the challenge test, was present in 32 (40%) children, and 90% of them were sensitized to at least one allergen. Early asthma-predictive factors were atopic dermatitis (odds ratio (OR), 3.5; 95% confidence interval (CI), 1.2-10.1) and the presence of specific IgE to inhalant allergens (OR, 11.3; 95% CI, 1.9-67.6). Respiratory syncytial virus (RSV) identification during wheezing in infancy was relatively rare (20%) among later asthmatics compared with other or no viral identification (52%) or rhinovirus identification (58%). Since the prevalence of childhood asthma in our area is 4.0-5.0%, we conclude that the increased risk of asthma persists until the teenage years after hospitalization for wheezing in infancy. The risk was about 5-fold after respiratory syncytial virus-induced wheezing, and more than 10-fold after rhinovirus-induced wheezing in the present study.

Relation of beta2-adrenoceptor polymorphisms at codons 16 and 27 to persistence of asthma symptoms after the onset of puberty

BACKGROUND

It has long been recognized that many children with asthma outgrow the disease after the onset of puberty, but little is known about genetic factors influencing this outcome.

OBJECTIVES

The aim of the present study was to determine whether the polymorphisms at codons 16 and 27 of the beta2-adrenoceptor are significant predictors of the persistence of asthma during adolescence.

DESIGN AND PARTICIPANTS

We used data from the prospective Tucson Children's Respiratory Study. Children were genotyped for the polymorphisms at codons 16 and 27. The presence of wheezing/asthma was assessed by questionnaire from age 6 years up to the reported onset of puberty (prepubertal period) and after the onset of puberty up to age 16 years (adolescence).

RESULTS

Among children who wheezed in the prepubertal period (n = 168), subjects homozygous for Gly at codon 16 were at significantly increased risk for persistent wheezing after puberty, as compared with carriers of the other genotypes (relative risk [RR], 1.43; 95% confidence interval [CI], 1.06 to 1.92; p = 0.019). This relation was present among boys (RR, 2.17; 95% CI, 1.41 to 3.36) but not girls (RR, 0.85; 95% CI, 0.55 to 1.30), and increased linearly according to the frequency of wheezing episodes after the onset of puberty. These findings persisted after adjusting for ethnicity and other potential confounders and after selecting only white children. The polymorphism at codon 27 showed no relation with risk for persistent wheezing.

CONCLUSIONS

This study provides evidence for a strong gender-specific effect of the Gly16 polymorphism on the persistence of asthma after the onset of puberty.

Environment and development of atopy

PURPOSE OF REVIEW

Asthma and other atopic disorders are the result of complex interactions between genetic predisposition and multiple environmental influences. However, the marked increase in asthma prevalence over recent decades is unlikely to be due to genetic changes, highlighting the contribution of environmental factors to the process of allergic sensitization.

RECENT FINDINGS

This article reviews recent information on environmental influences on the development of atopy in children. Both observational and interventional studies continue to shed new light on the critical influence of early life events--such as events in pregnancy, exposure to allergens and endotoxin, pet ownership, infections, family size--and have highlighted important gene-environment interactions that modify the relationships between environmental exposures and atopic outcomes.

SUMMARY

The future is likely to see a concerted effort to further define the role that these environmental exposures play in allergic sensitization and the expression of atopic diseases, in order to provide a rational platform on which to develop new methods of allergy prevention that can be targeted at high-risk children.

Obesity and asthma, what are the links?

PURPOSE OF REVIEW

Obesity is a major cause of morbidity accounting for approximately 300 000 deaths each year and about 7% of the health care budget with an economic impact greater than US dollar 100 billion annually in the United States. Obesity and its sequelae such as cardiovascular disease, diabetes, arthritis or cancer have been on the rise over the last decades. The parallel time trend with an increasing prevalence of asthma has induced a lively debate about a potential link between both conditions.

RECENT FINDINGS

A number of prospective studies have shown that weight gain can antedate the development of asthma. Effect modification by sex may occur as some studies have shown effects of body mass index on asthma only among females. However, sex differences are not consistent. Several hypotheses have been proposed to explain the epidemiological associations including alterations in airway mechanics and immune responses, hormonal influences and genetic factors.

SUMMARY

There is evidence that obesity and overweight are associated with the development of asthma. Yet, the mechanisms underlying this relation are unclear. Weight reduction among asthmatic patients can result in improvements of lung function demonstrating the potential clinical impact of the findings.

Decreased physical activity among Head Start children with a history of wheezing: use of an accelerometer to measure activity

Asthma is a severe problem among inner city children, and recent evidence suggests that both allergen exposure and lifestyle can impact the disease early in childhood. This study was designed to investigate the association between physical activity and wheezing among a population of inner city children enrolling in Head Start. The parents of children aged 3-5 years responded to a questionnaire (N = 144) to determine the presence and severity of wheezing and asthma. Information was also gathered regarding home environment, food frequency, and presence of other allergic diseases. Serum was obtained to measure total IgE and specific IgE levels to common allergens. Height and weight for body mass index were recorded. Lastly, motion sensor wristwatches (Actiwatch) were worn continuously by a subset of these children (n = 54) for 6 or 7 days. Physical activity measured with the motion sensor was decreased among children with a history of wheezing. The significant differences involved those measures of activity relating to prolonged or sustained physical activity. The correlates of asthma associated with decreased levels of physical activity included: 1) a history of wheezing in the last 12 months, 2) the diagnosis of asthma, and 3) presentation to the emergency room in the last 12 months for wheezing or asthma. In a preschool-age population, decreased physical activity was observed among children with a history of asthma or wheezing. Decreased physical activity could contribute to persistence of asthma or put children at higher risk for obesity and other chronic diseases.

Overlap of asthma and chronic obstructive pulmonary disease

PURPOSE OF REVIEW

Asthma and chronic obstructive pulmonary disease (COPD) are both defined by the presence of airflow obstruction, but they present distinguishing differences in terms of both risk factors and clinical phenotypes. Yet it is quite common in the clinical setting to observe patients with asthma showing COPD-like phenotypes, and vice versa, making it a priority to search for optimal prevention, treatment, and management strategies for these cases of coexisting lung obstructive diseases.

RECENT FINDINGS

Recent studies have provided further evidence of strong epidemiologic and clinical links between asthma and COPD. Adult subjects with active asthma are as much as 12 times more likely to acquire COPD over time than subjects with no active asthma. Signs identifying patients with asthma predisposed to developing COPD may already be present at the early stages of the disease, a finding with potential implications for prevention of COPD. In addition to spirometry and other pulmonary function tests (such as measurements of residual volume and diffusing capacity of the lung for carbon monoxide), recent evidence suggests that the assessment of type and degree of airway remodeling and the evaluation of inflammatory markers might prove useful in the future to characterize phenotypically patients with coexisting asthma and COPD.

SUMMARY

The nature of the association between asthma and COPD remains unclear and open to discussion. Further research is required to develop effective management algorithms for patients with multiple obstructive lung diseases, determine to what extent early treatment and optimal management of asthma may protect against progression into COPD, and identify genetic markers of individual susceptibility to specific lung disease phenotypes and pharmacologic treatments.

Spontaneous sigh rates during sedentary activity: watching television vs reading

BACKGROUND

Spontaneous sighs are thought to play an important role in preventing atelectasis and in regulating airway tone. Recent studies have provided a mechanism by which expansion of the lungs could cause relaxation of smooth muscle.

OBJECTIVE

To investigate breathing patterns during 2 forms of sedentary behavior: reading and watching television.

METHODS

Breathing patterns were monitored for 1 to 2 hours to document respiratory rates and sigh rates. Each participant was monitored while reading and while watching a movie on videotape. During the first experiment (17 controls), metabolic rates were also measured. In the second experiment (18 controls and 9 patients with mild-to-moderate asthma), only breathing patterns were monitored.

RESULTS

There were no significant differences in respiratory or metabolic rates between the 2 activities. In contrast, in the first experiment, 13 of 17 controls had lower sigh rates while watching a videotape than while reading (P < .01). In the second experiment, the sigh rate was significantly lower overall while watching a videotape (mean, 13.7 sighs per hour; range, 1.8-26.0 sighs per hour) than while reading (mean, 19.3 sighs per hour; range, 7.7-30.0 sighs per hour) (P < .001). A similar decrease was observed in patients with asthma (P < .01).

CONCLUSIONS

Given that many children and adults watch television for 5 or more hours per day, breathing patterns during this time may be relevant to lung function. Our results demonstrate that prolonged periods of watching a videotape are associated with lower sigh rates than while reading. Further research is needed to determine whether these changes are relevant to increased bronchial reactivity.

Asthma and panic in young adults: a 20-year prospective community study

RATIONALE

Psychologic factors are increasingly recognized to influence the onset and course of asthma. Previous cross-sectional community-based studies have provided evidence for a relatively specific association between asthma and panic.

OBJECTIVES

To examine concurrent and longitudinal associations between asthma and panic in young adults.

MEASUREMENTS AND MAIN RESULTS

Prospective community-based cohort study of young adults (n = 591) followed between ages 19 and 40. Information was derived from six subsequent semistructured diagnostic interviews conducted by professionals. Cross-sectionally (over the whole study period), asthma was more strongly associated with panic disorder (odds ratio [OR] = 4.0; 95% confidence interval [CI], 1.7, 9.3) than with any panic, which included panic disorder and panic attacks (OR = 2.1; 95% CI, 1.1, 4.5). Longitudinally, after adjusting for potentially confounding variables, active asthma predicted subsequent panic disorder (OR = 4.5; 95% CI, 1.1, 20.1), and the presence of panic disorder predicted subsequent asthma activity (OR = 6.3; 95% CI, 2.8, 14.0). Asthma predicted any panic (OR = 2.7; 95% CI, 1.1, 7.1), whereas any panic did not predict subsequent asthma activity. Associations were stronger in smokers than in nonsmokers, and stronger in women than in men. Smoking, early-childhood anxiety, and a family history of allergy were important confounders of the asthma-panic association.

CONCLUSIONS

This is the first long-term follow-up study on asthma and panic. It showed dose-response-type relationships between panic and asthma, and bidirectional longitudinal associations between the two conditions. It provided evidence for familial factors and smoking as possible shared etiologic explanations.

Asthma severity and prevalence: an ongoing interaction between exposure, hygiene, and lifestyle

Why are the prevalence and severity of asthma increasing? Platts-Mills looks at the key studies that can help to anwer this important question

On roots of childhood asthma: the role of respiratory infections

The prevalence of childhood asthma has increased throughout the last decades, but the reasons for the increase still remain unresolved. However, the debate has recently focused on the role of infections, and microbial exposure in general, in the development of childhood asthma. Many studies have suggested that there is an inverse relation between certain infections and the risk of asthma. This article outlines the contemporary role of childhood asthma in public health, reviews the importance of topical respiratory pathogens in the development of childhood asthma, and provides an example how selection bias may have caused controversy in previous studies assessing the role of infections in the development of childhood asthma.

Sex differences in the relation between body mass index and asthma and atopy in a birth cohort

RATIONALE

Several studies have identified an association between asthma and obesity in women. It remains unclear if this association is due to genuine asthma or to symptoms caused by overweight, at what age the association develops, and whether it is confined to females.

OBJECTIVE

To explore the relations between body mass index, asthma, and atopy in a birth cohort of approximately 1,000 individuals.

METHODS

Information on asthma and measurements of lung function, airway responsiveness, and atopy were obtained on multiple occasions between ages 9 and 26. Associations between these outcomes and body mass index were analyzed using generalized mixed linear regression models. Further analyses adjusted for potential covariates including breastfeeding, birth order, parental asthma, and personal and family smoking history.

MAIN RESULTS

Body mass index was positively associated with asthma, wheeze, asthma treatment, atopy, immunoglobulin E, and inversely with the FEV(1)/FVC ratio in females. There was no significant association with airway responsiveness to methacholine or salbutamol. There was little evidence of an association between body mass index and asthma or atopy in males. Analyses adjusting for potential covariates showed similar findings. Asthma was not associated with a raised body mass index in childhood and childhood asthma did not lead to being overweight as an adult.

CONCLUSIONS

A raised body mass index is associated with asthma and atopy in women but not men. Population attributable fraction calculations estimate that 28% (95% confidence interval 7-45) of asthma developing in women after age 9 is due to overweight.

Asthma severity is associated with body mass index and early menarche in women

Asthma severity in relation to body mass index (BMI) has rarely been studied. The relation between BMI and asthma severity was studied by sex in 366 adults with asthma from the Epidemiological Study on the Genetics and Environment of Asthma, a case-control and family study on asthma. Factors related to asthma severity and BMI such as smoking, FEV(1), bronchial hyperresponsiveness, and dyspnea were taken into account. The influence of early menarche was studied to assess the potential role of hormonal factors. Clinical asthma severity in the last 12 months was assessed by a score (0-7) based on the frequency of asthma attacks, persisting symptoms between attacks, and hospitalization. Asthma severity, which was unrelated to sex, increased with BMI in women (p = 0.0001) but not in men (p = 0.3). In women, the association remained after adjustment for age, FEV(1), smoking habits, and BMI-adjusted dyspnea and taking into account familial dependence (p = 0.0001). The association between BMI and severity was stronger in women with early menarche than in women without early menarche (p interaction = 0.02). Findings support the hypothesis of hormonal factors involved in the severity of asthma.