A prospective study of asthma in a rural community

Structural lung abnormalities on computed tomography correlate with asthma inflammation in bronchoscopic alveolar lavage fluid

Objective: Image scoring systems have been developed to assess the severity of specific lung abnormalities in patients diagnosed with various pulmonary diseases except for asthma. A comprehensive asthma imaging scoring system may identify specific abnormalities potentially linking these to inflammatory phenotypes.Methods: Computed tomography (CT) images of 88 children with asthma (50 M/38 F, mean age 7.8 ± 5.4 years) acquired within 12 months of bronchoscopic alveolar lavage fluid (BALF) sampling that assessed airway inflammation cell types were reviewed along with CT images of 49 controls (27 M/22 F, mean age 3.4 ± 2.2 years). Images were scored using a comprehensive scoring system to quantify bronchiectasis (BR), bronchial wall thickening (BWT), ground glass opacity, mucus plugging (MP), consolidations, linear densities (LD), and air trapping (AT). Each category was scored 0-2 in each of six lobar regions (with lingula separated from left upper lobe).Results: Absolute average overall scores of the controls and children with asthma were 0.72 ± 1.59 and 5.39 ± 5.83, respectively (P < 0.0001). Children with asthma scored significantly higher for BR (N = 20, 0.33 ± 0.80, P = 0.0002), BWT (N = 28, 0.72 ± 1.40, P < 0.0001), MP (N = 28, 0.37 ± 1.12, P = 0.0052), consolidation (N = 31, 0.67 ± 1.22, P < 0.0001), LD (N = 58, 1.12 ± 1.44, P < 0.0001), and AT (N = 52, 1.78 ± 2.31, P < 0.0001). There was a significant difference between the BR score of children with positive inflammatory response in BALF (N = 53) and those who were negative for airway inflammation cells (0.14 ± 0.36, P = 0.040).Conclusions: Significant lung structural abnormalities were readily identified on CT of children with asthma, with image differentiation of those with an inflammatory response on BALF. Chest imaging demonstrates potential as a noninvasive clinical tool for additional characterization of asthma phenotypes.

Majority of never-smokers with airflow limitation do not have asthma: the Copenhagen General Population Study

BACKGROUND

A substantial proportion of individuals with airflow limitation are never-smokers. However, whether never-smokers with airflow limitation have undiagnosed asthma is unknown. We hypothesised that the majority of never-smokers with respiratory symptoms and airflow limitation but without known asthma have undiagnosed asthma by comparing characteristics and prognosis in never-smokers with airflow limitation and asthma (NS+AFL+A) with never-smokers with airflow limitation but without asthma (NS+AFL-A).

METHODS

Among 94 079 participants aged 20-100 years from the general population, 39 102 (42%) were never-smokers. In this group, 13 719 (35%) reported to have respiratory symptoms of whom 1610 (12%) had airflow limitation. We investigated characteristics and risk of complications (asthma or COPD exacerbations, pneumonias and all-cause mortality) and comorbidities (lung cancer, ischaemic heart disease, myocardial infarction, deep venous thrombosis and PE) during 4.5 years median follow-up.

RESULTS

NS+AFL-A compared with NS+AFL+A reported less allergy and respiratory symptoms, and had higher FEV1 and lower levels of eosinophils and IgE in peripheral blood. NS+AFL+A had increased risk of asthma and COPD exacerbations, but not of pneumonias; adjusted HRs in NS+AFL+A compared with NS+AFL-A were 16 (95% CI 3.7 to 73) for asthma exacerbations and 15 (2.8 to 80) for COPD exacerbations. Still, NS+AFL-A had increased risk of COPD exacerbations and pneumonias, but not of asthma exacerbations; adjusted HRs in NS+AFL-A compared with never-smokers without airflow limitation or asthma (NS-AFL-A) were 7.7 (2.8 to 21) for COPD exacerbations and 1.7 (1.3 to 2.3) for pneumonias. Risk of comorbidities or all-cause mortality was not increased in NS+AFL-A or NS+AFL+A compared with NS-AFL-A.

CONCLUSIONS

Majority of NS+AFL-A do not seem to have undiagnosed asthma and may instead have airflow limitation caused by other risk factors.

The relation of airway obstruction to asthma, chronic rhinosinusitis and age: results from a population survey of adults

RATIONALE

There is conflicting evidence on whether patients with asthma experience an accelerated decline in lung function with age. We examined the association between postbronchodilator lung function, asthma, chronic rhinosinusitis (CRS), and atopy with age using a large European sample.

METHODS

In 17 centers in 11 European countries, case-control studies were nested within representative cross-sectional surveys of adults aged less than 75 years. Representative samples of participants with asthma, CRS or both and controls were assessed for postbronchodilator ventilatory function, smoking history, atopy, and treatment. Multiple regression was used to assess the interactive effects of age and diagnostic group on decline in postbronchodilator ventilatory function.

RESULTS

A total of 3337 participants provided adequate data (778 with asthma, 399 with CRS, 244 with both asthma and CRS and 1916 controls who had neither asthma nor CRS). Participants with asthma had lower FEV1 /FVC (-4.09% (95% CI: -5.02, -3.15, P < 0.001) and a steeper slope of FEV1 /FVC against age (-0.14%/annum [95%CI: -0.19, -0.08]) equivalent to smoking 1-2 packs of cigarettes per day. Those with atopy had a slope equivalent to controls.

CONCLUSIONS

People with asthma have a steeper decline in postbronchodilator lung function with age, but neither CRS nor atopy alone were associated with such decline.

Longitudinal changes in airway remodeling and air trapping in severe asthma

RATIONALE AND OBJECTIVES

Previous cross-sectional studies have demonstrated that airway wall thickness and air trapping are greater in subjects with severe asthma than in those with mild-to-moderate asthma. However, a better understanding of how airway remodeling and lung density change over time is needed. This study aimed to evaluate predictors of airway wall remodeling and change in lung function and lung density over time in severe asthma.

MATERIALS AND METHODS

Phenotypic characterization and quantitative multidetector-row computed tomography (MDCT) of the chest were performed at baseline and ∼2.6 years later in 38 participants with asthma (severe n = 24 and mild-to-moderate n = 14) and nine normal controls from the Severe Asthma Research Program.

RESULTS

Subjects with severe asthma had a significant decline in postbronchodilator forced expiratory volume in 1 second percent (FEV1%) predicted over time (P < .001). Airway wall thickness measured by MDCT was increased at multiple airway generations in severe asthma compared to mild-to-moderate asthma (wall area percent [WA%]: P < .05) and normals (P < .05) at baseline and year 2. Over time, there was an increase in WA% and wall thickness percent (WT%) in all subjects (P = .030 and .009, respectively) with no change in emphysema-like lung or air trapping. Baseline prebronchodilator FEV1% inversely correlated with WA% and WT% (both P < .05). In a multivariable regression model, baseline WA%, race, and health care utilization were predictors of subsequent airway remodeling.

CONCLUSIONS

Severe asthma subjects have a greater decline in lung function over time than normal subjects or those with mild-to-moderate asthma. MDCT provides a noninvasive measure of airway wall thickness that may predict subsequent airway remodeling.

Epidemiology of adult asthma in Asia: toward a better understanding

Asia is the world's most dynamic area. Asthma is a major chronic disease in Asia, like other continents. However, unlike childhood asthma, the epidemiological burden of asthma in Asian adults has been unclear. Here we reviewed the currently available literatures on the epidemiology of adult asthma in the Asian community populations. Adult asthma prevalence was generally lower in Asian than in Europe, but the increasing trends suggested the disease burden to rise in the near future. However, for better understanding, it may be essential to prepare for the Asian multinational network for the standardization and collaboration of research.

An official American Thoracic Society public policy statement: Novel risk factors and the global burden of chronic obstructive pulmonary disease

RATIONALE

Although cigarette smoking is the most important cause of chronic obstructive pulmonary disease (COPD), a substantial proportion of COPD cases cannot be explained by smoking alone.

OBJECTIVES

To evaluate the risk factors for COPD besides personal cigarette smoking.

METHODS

We constituted an ad hoc subcommittee of the American Thoracic Society Environmental and Occupational Health Assembly. An international group of members was invited, based on their scientific expertise in a specific risk factor for COPD. For each risk factor area, the committee reviewed the literature, summarized the evidence, and developed conclusions about the likelihood of it causing COPD. All conclusions were based on unanimous consensus.

MEASUREMENTS AND MAIN RESULTS

The population-attributable fraction for smoking as a cause of COPD ranged from 9.7 to 97.9%, but was less than 80% in most studies, indicating a substantial burden of disease attributable to nonsmoking risk factors. On the basis of our review, we concluded that specific genetic syndromes and occupational exposures were causally related to the development of COPD. Traffic and other outdoor pollution, secondhand smoke, biomass smoke, and dietary factors are associated with COPD, but sufficient criteria for causation were not met. Chronic asthma and tuberculosis are associated with irreversible loss of lung function, but there remains uncertainty about whether there are important phenotypic differences compared with COPD as it is typically encountered in clinical settings.

CONCLUSIONS

In public health terms, a substantive burden of COPD is attributable to risk factors other than smoking. To prevent COPD-related disability and mortality, efforts must focus on prevention and cessation of exposure to smoking and these other, less well-recognized risk factors.

The importance of airway remodelling in the natural course of asthma

INTRODUCTION

Asthma is associated with airflow limitation and increased decline in lung function. The underlying mechanism for this was probably that persisting inflammation leads to remodelling of the airways.

OBJECTIVES

To review the importance of different factors which are related to airflow limitation and lung function decline in asthma.

METHODS

Case report and literature review.

RESULTS

Asthma severity, smoking, bronchial hyperresponsiveness and eosinophil inflammation were the variables that were most convincingly related to decline in forced expiratory volume in 1 s (FEV(1)) in asthma. Treatment with inhaled corticosteroids probably decreased the rate of FEV(1) decline, although this was more uncertain because of the lack of randomised double blind studies that show such an effect. Progress in the field of the genetics of asthma may, in the near future, elucidate the role of gene-environment interaction in lung function decline in asthma.

CONCLUSION

Regular treatment with inhaled corticosteroids may partly have a beneficial effect on airway remodelling in asthma. Improved understanding of the processes leading to airway remodelling is, however, important in order to prevent a large number of asthmatics from developing irreversible airflow obstruction.

[Impact of low socioeconomic status on the demography and co-morbidities of asthma]

OBJECTIVES

Asthma is a frequent and serious chronic respiratory disease which is sometimes fatal. It involves all ages and all social subclasses. The goal of our study was to determine the demography of asthma in a low socio-economic community in Lebanon and to describe its association with various epidemiologic factors.

MATERIALS AND METHODS

The computerized data of 44.814 patients of a nongovernmental organization (Hariri Foundation), in Lebanon were reviewed. Asthmatic patients diagnosed by a health professional on the basis of medical criteria during the period from January 2003 to June 2005 were included in the analysis. The socio-economic characteristics of this population were retrieved and their geographical distributions were depicted. The study focused on the association of asthma with cutaneous and ocular allergies, depression, obesity and alcohol consumption.

RESULTS

The majority of asthmatic patients (75%) belonged to a low socio-economic environment with a salary lower than $200 per month. 31% were illiterate. 583 (1.3%) of patients on the database were asthmatic. The rate in children was higher (2.08%) than in adults (1.09%). The majority of asthma occurred among subjects from Bekaa valley and South Lebanon. Asthma was associated more strongly with being an ex-smoker (OR 4.37; 95% CI 2.38, 8.02) than being a current smoker (OR 1.44; 95% CI 1.11, 1.87). A significant and strong association was found with depression (OR 25.6; 95% CI 3.32, 197.6), obesity (OR 4.09, 95% CI 1.31, 12.73) and with regular alcohol consumption (OR 11.78; 95% CI 1.55, 89.44).

CONCLUSION

This study describes the association of asthma in this population with low socio-economic status. By defining the demographic characteristics of the asthma population the Ministry of Health and the medical organizations concerned should be better able to manage the condition. This study confirms, in a Lebanese population, the epidemiological associations described in other populations around the world.

Outcome and severity of adult onset asthma--report from the obstructive lung disease in northern Sweden studies (OLIN)

BACKGROUND

Studies of longitudinal changes in severity and the long-term outcome of asthma in epidemiological settings are uncommon.

AIM

To assess the outcome of incident asthma in a cohort of subjects who developed asthma after the age of 20 years.

METHODS

This is a prospective study of the outcome of 309 subjects with incident asthma being included in a case-referent study based on all adults aged 20-60 years living in three municipalities/towns in Northern Sweden. The subjects fulfilled the criteria for incident asthma defined as onset of symptoms common in asthma within 12 months prior to the study and a verified bronchial variability. In 2003, 250 (81%) of the subjects with asthma were re-examined with structured interview, lung-function test and methacholine test.

RESULTS

At follow-up, 237 (95%) subjects still had an active asthma, i.e. they had symptoms or used asthma medicines. Among those with active asthma, 65% were using inhaled cortico-steroids. Severity grading (GINA 2000) showed that 21% had mild intermittent asthma, 30% mild persistent, 44% moderate persistent, and 5% severe asthma, contrasting to 75% with moderate or severe asthma at entry. Higher age, higher BMI and low lung function were associated with greater asthma severity. Twelve subjects (5%) were in remission. Predictors for remission were non-sensitisation and a normal lung function. Age, sex, BMI, and smoking habits were not significantly different between those in remission and those not.

CONCLUSIONS

Remission of adult onset asthma was low. Severity of asthma changed considerably over time, however, the overall change was towards a milder disease probably as a result of treatment.

Rising trend of asthma prevalence among Turkish schoolchildren (ISAAC phases I and III)

BACKGROUND

Asthma is a common chronic illness in childhood. The aim of the study was to examine time trends in the prevalence of asthma using the ISAAC questionnaire in 6- to 12-year-old schoolchildren in Istanbul and factors affecting asthma prevalence.

METHODS

Two cross-sectional surveys were performed, 9 years apart (1995 and 2004) using the ISAAC protocol. The survey conducted in 1995 was repeated in 2004 using the same questionnaire in the same age group, in the same schools in the same season. The 2500 questionnaires were distributed to the children to be completed by their parents at home.

RESULTS

A total of 2387 children (response rate 95.5%) in the 2004 study and 2216 children (response rate 94.3%) in 1995 were included in the final analysis. The overall lifetime prevalence of wheeze increased from 15.1% to 25.3%; prevalence odds ratio (POR) = 1.91, 95% confidence interval (95% CI) = 1.64-2.21, and P < 0.001. The overall 12-month prevalence of wheeze increased from 8.2% to 11.3%; POR = 1.43, 95% CI = 1.18-1.75, and P < 0.001. The prevalence of asthma increased significantly from 9.8% to 17.8%; POR = 1.99, 95% CI = 1.67-2.36, and P < 0.001. In both 1995 and 2004, family history of asthma, eczema diagnosed by a physician, food allergy diagnosed by a physician, frequent otitis, frequent sinusitis were associated significantly with high risk for asthma.

CONCLUSIONS

In the 9-year period from 1995 to 2004, the prevalence of asthma symptoms has increased in 6- to 12-year-old schoolchildren in Istanbul. Risk factors affecting asthma prevalence remained unchanged during the 9-year period.

Respiratory findings in a nursing home population

The prevalence of respiratory abnormalities was studied in an elderly nursing home population. This study investigated 475 female and 147 male individuals living in five nursing homes in Zagreb, Croatia. Chronic respiratory symptoms were recorded using the British Medical Research Council questionnaire. Ventilatory capacity was measured with maximum expiratory flow-volume (MEFV) curves on which forced vital capacity (FVC), one-second forced expiratory volume (FEV1), maximum expiratory flow rate at 50% FVC (FEF50), and maximum expiratory flow rate at 25% FVC (FEF25) were measured. A high rate of chronic respiratory illness and symptoms was found in both female and male nursing home residents. The highest rates were for asthma, chronic cough, and for chest tightness. Odds ratios (OR) showed that smoking and the length of employment were significant risk factors among men. Pulmonary function testing demonstrated a decrease in measured values compared to predicted (p<0.01). This was particularly pronounced for FEF50 and FEF25, suggesting obstructive changes in smaller airways. Regression coefficients were significant for smoking and employment primarily for FEF50 and FEF25. Our data suggest that older individuals residing in nursing homes exhibit an excess of respiratory symptoms, and lung function abnormalities. Smoking and past employment are important risk factors for these respiratory findings. Medical surveillance and preventive strategies should be implemented for this high risk population.

Asthma management issues in infancy and childhood

The prevalence of asthma has been increasing worldwide over the past 2 decades, especially the prevalence of childhood asthma. Currently, the prevalence of childhood asthma is around 3-20% in different countries based on the report from the International Study of Asthma and Allergies in Children (ISAAC). Asthma in childhood is predominantly an extrinsic asthma. In general, countries in the coastal, temperate, and subtropical zones have the highest prevalence of mite- and cockroach-sensitive asthma. Countries in the sub-arctic or semi-arid areas have a lower prevalence of childhood asthma, mostly associated with sensitization to pet dander, moulds, and pollens. Many genes have been linked to asthma in different ethnic populations. A global consensus for the management of asthma in adults and children >5 years of age has been made possible in the Global Initiative for Asthma (GINA) guidelines, where a step-wise management program using inhaled medication with and without oral anti-inflammatory drugs is recommended. The management of asthma in children <5 years of age remains inconclusive. Recent studies suggest that inherited susceptibility associated with risk factors from the prenatal and postnatal environment is likely to promote allergic sensitization and development of asthma. Consequently, early prevention of prenatal sensitization in utero and environmental control of early life exposure to various allergens may decrease the incidence of childhood asthma. In the management of moderate persistent asthma in infants and young children <5 years of age, airway resistance tests (FEV(1) or PEF) are not of significance, but assessment of respiratory rate and skin pulse oximeter measurements of arterial oxygen saturation are helpful. Moreover, recent advances in pharmacogenetics and pharmacogenomics may provide better individualized care for early pharmacological prevention of childhood asthma via selective modulation of airway remodeling.

Rationale for the Dutch hypothesis. Allergy and airway hyperresponsiveness as genetic factors and their interaction with environment in the development of asthma and COPD

The Dutch hypothesis, formulated in the 1960s, holds that the various forms of airway obstruction are different expressions of a single disease entity. It suggests that genetic factors (eg, airway hyperresponsiveness [AHR] and atopy), endogenous factors (eg, sex and age), and exogenous factors (eg, allergens, infections, and smoking) all play a role in the pathogenesis of chronic nonspecific lung disease. This review finds evidence that AHR and smoking are common risk factors for asthma and COPD. To prove the Dutch hypothesis definitively, however, genetic studies, preferably longitudinal, must be performed. Such studies must include subjects who have airway obstruction that does not necessarily meet the current strict definitions of asthma or COPD (ie, the extremes of these conditions) that are used in clinical studies.

Longitudinal decline in pulmonary function in atopic cough and cough variant asthma

OBJECTIVE

Cough variant asthma and atopic cough are different clinical manifestations of eosinophilic airway inflammation presenting with isolated chronic non-productive cough. The aim of this study was to examine the longitudinal change in pulmonary function in cough variant asthma and atopic cough.

METHODS

Longitudinal change in FEV1 was prospectively examined in 20 patients with cough variant asthma, 14 patients with atopic cough and 271 asymptomatic healthy subjects. All were lifetime non-smokers. Of the 20 cough variant asthma patients, 13 were taking long-term inhaled corticosteroid therapy (ICS) (beclomethasone dipropionate 615 +/- 58 micro g/day) and the other seven were not. Spirometry was taken at first visit, after cough was almost completely relieved on therapy, and at least once every year for 5 or more years afterwards.

RESULTS

The slope of longitudinal change in FEV1 was not significantly different among cough variant asthma patients (- 0.029 +/- 0.007/year), atopic cough patients (- 0.021 +/- 0.022/year) and asymptomatic subjects (- 0.028 +/- 0.002 L/year). In patients with cough variant asthma, the slope in patients not taking inhaled corticosteroids (ICS) was 0.032 +/- 0.007 L/year, which was not significantly different from that in patients taking ICS (- 0.027 +/- 0.010 L/year).

CONCLUSION

Pulmonary function decline is not greater in cough variant asthma than atopic cough and the normal population, and long-term ICS has no effect on the decline in cough variant asthma.

Effects of childhood respiratory diseases on the anatomical and functional development of the respiratory system

The anatomical and functional development of the lung appears especially vulnerable to a whole range of insults during gestation and the first few years of life. A significant proportion of adult lung disease originates in utero or early infancy. Most publications on this topic are descriptive retrospective studies. An important limitation of these is that structural changes may precede abnormalities in lung function and development of symptoms. Little is known with certainty with respect to the long-term effects of early insults to the respiratory system. Furthermore, the reversibility of the functional and/or structural defects is hardly ever adequately investigated and it is probably not correct to extrapolate findings from adult studies to paediatric pulmonary diseases. Promoting or facilitating optimal lung growth in fetuses and infants and reducing the incidence of lower respiratory tract infection in infancy may reduce the incidence of adult chronic lung disease in generations to come.

Factors associated to lifestyle and risk of adult onset asthma

BACKGROUND

Asthma prevalence has been increasing especially in developed countries. The change seems to be associated with changes in lifestyle. We have made a prospective study to assess the effect of lifestyle factors, including smoking, educational level, physical activity and obesity on adult onset asthma.

METHODS

A population of 10,597 adult twins, initially free of asthma was followed for 9 years. The main outcome measure was questionnaire-based report of physician diagnosed asthma. Logistic regression was used to estimate the risk of asthma predicted by lifestyle factors, with adjustment for atopy and respiratory symptoms.

RESULTS

Obesity at baseline increased asthma risk (multivariable adjusted OR = 3.00, 95% CI: 1.64-5.50 for those with BMI > or = 30 compared to those with normal weight BMI: 20-24.99). Taller height was associated to lower asthma incidence. Leisure time physical activity had a slightly protective effect on asthma risk among men (P for trend = 0.037) while smoking and education did not have significant effects on the risk of adult onset asthma.

CONCLUSIONS

Obesity was associated to the risk of adult onset asthma, while short height and low leisure time physical activity can be considered as other potential risk factors.

Pharmacotherapy and airway remodelling in asthma?

Over the last few decades attention has largely focused on airway inflammation in asthma, but more recently it has been appreciated that there are important structural airway changes which have been grouped together under the term "airway remodelling". It is only now that questions have been asked about the impact of treatment on these structural changes. This review examines the nature of these structural airway changes, the mechanisms of their generation, their potential consequences, and what is known about the ability of anti-asthma treatments to modulate these changes.

Relationship between separation anxiety disorder, parental panic disorder, and atopic disorders in children: a controlled high-risk study

OBJECTIVE

To test the hypotheses that rates of atopic disorders are elevated in offspring of parents with panic disorder (PD) and in children with separation anxiety disorder (SAD).

METHOD

Rates of atopic disorders were assessed in 343 offspring (aged 6-17 years) of parents with PD, nonpanic psychiatric disorders, and no psychiatric disorder. Lifetime history of atopic disorders was determined by parental responses to a clinician-administered questionnaire assessing medical treatment for asthma and allergies. Logistic regression analyses assessed the association between atopic disorders and parental PD, and between atopic disorders and probable or definite childhood SAD. Analyses controlled for age, sex, socioeconomic status, and treatment for other medical illnesses.

RESULTS

Increased rates of atopic disorders were found in offspring of parents with PD (odds ratio [OR] = 2.56, 95% confidence interval [CI] = 1.27-5.16, p = .009) and in children with SAD (OR = 2.71, 95% Cl = 1.22-6.03, p = .015). Associations remained significant when both parental PD and SAD were included in the model, suggesting that each contributed independently to increased rates of atopy. The interaction of parental PD and child SAD was not significant.

CONCLUSIONS

Atopic disorders in children are associated with parental PD and with childhood SAD. Results do not appear to support that having both childhood SAD and a parent with PD confers increased risk for atopic disorders above and beyond either condition alone.

Asthma and smoking status in a population-based study of California adults

OBJECTIVE

Because they experience respiratory symptoms, adults with asthma might be expected to avoid cigarette smoking. However, previous studies have not adequately addressed whether adults with asthma have a lower prevalence of smoking than the general population. The authors sought to determine whether adult asthmatics are less likely to smoke cigarettes than members of the general population.

METHODS

The authors used data from a random sample of 2,902 California adults ages 18 years or older,with oversampling of African Americans, Asian/Pacific Islanders, adults with disabilities, and adults aged 45 to 70 years. Sampling weights were used in all analyses. In this cross-sectional study, 217 participants (7.5%) reported a physician diagnosis of asthma.

RESULTS

The prevalence of "ever smoking" was similar among adults with asthma (48.3%) and those without asthma (43.0%) (risk difference 5.3%; 95% CI -1.6%, 12.2%). There was also no difference in the prevalence of "current smoking" among adults with asthma (20.2%) compared with the non-asthmatic subjects (18.8%) (risk difference 1.4%; 95% CI -4.2%, 6.9%). After controlling for age, gender, race, and education, there was no evidence that adults with asthma were less likely to ever smoke. Although the confidence intervals did not exclude "no association," asthma was actually associated with an increased risk of ever smoking (OR 1.3; 95% CI 1.0, 1.8). There was also no association between asthma and the risk of current smoking after controlling for covariates (OR 1.1; 95% CI 0.8, 1.6). Moreover, there were no differences in "age of smoking initiation," "duration of smoking," or "intensity of smoking" after adjusting for demographic characteristics. Redefining the referent group to exclude respondents with other chronic lung diseases did not appreciably change study conclusions.

CONCLUSION

Adults with asthma do not appear to selectively avoid cigarette smoking. Specific smoking prevention and cessation efforts should be targeted to adults with asthma.

Step one for asthma treatment: Beta2-agonists or inhaled corticosteroids?

Inhaled corticosteroids have proven effectiveness in chronic persistent asthma and are now recommended as first-line therapy in this condition. In contrast, long term preventative therapy is not currently considered necessary for patients with disease that is only mild and episodic. Recently, there has been growing interest in the possible benefits of using inhaled corticosteroids at an earlier stage in asthma, as soon as the condition is diagnosed. The concept of early intervention is supported by the recognition that airway inflammation is common to all grades of asthma, including early and mild disease. A number of studies have suggested that delayed introduction of inhaled corticosteroids in asthma can result in a poorer clinical response. The precise reason for this is unknown, although it may result from persistent uncontrolled inflammation leading to airway remodelling associated with airflow obstruction that is relatively resistant to therapy. There have also been suggestions that early intervention may alter the natural history of the disease, either to induce sustained remission or to prevent long term decline in lung function, but these effects have yet to be clearly established. On the basis of present knowledge, early intervention remains controversial, particularly in children. The Steroid Treatment As Regular Therapy (START) trial is a large, placebo-controlled, multicentre study that is currently comparing early and delayed use of inhaled corticosteroids in adults and children with newly diagnosed asthma. It is hoped that this study will resolve some of the present uncertainties, and lead to a better understanding of whether an early intervention strategy in asthma can be justified.

Initial improvements in lung function and bronchial hyperresponsiveness are maintained during 5 years of treatment with inhaled beclomethasone dipropionate and terbutaline

OBJECTIVES

Treatment with inhaled corticosteroids reduces bronchial hyperresponsiveness and relieves airways obstruction in patients with asthma. Up to now, it is unknown whether initial improvements are maintained over a long period of time. Therefore, we assessed whether initial improvements in FEV(1), provocative concentration of histamine causing a 20% fall in FEV(1) (PC(20)), and peak expiratory flow (PEF) persist with a constant dose of inhaled corticosteroids. Furthermore, we investigated whether FEV(1), PC(20), PEF indexes, and symptom scores improve after increasing the dose of inhaled corticosteroids in patients who did not respond sufficiently to treatment with beclomethasone dipropionate (BDP), 800 microg/d.

METHODS

Sixty-eight patients with bronchial hyperresponsiveness and airways obstruction completed a previous study on 3 years of treatment with terbutaline, 500 microg qid, and BDP, 200 microg qid. Fifty-eight of these patients participated in the current extension of another 2.5 years of follow-up. Every 6 months, FEV(1) and PC(20) were measured. Five patients dropped out of the study, one for pulmonary reasons. Forty-four patients continued treatment with BDP, 800 microg/d (BDP-800 group), and 9 patients received a higher dose of BDP (500 microg tid; BDP-1,500 group) after the first 3 years because of a rapid decline in FEV(1) (> 50 mL/yr) despite BDP treatment during the previous study period.

RESULTS

After the initial improvement, the mean slope of individual regression lines for FEV(1), PC(20), and morning PEF were - 28 mL/yr, - 0.01 doubling concentrations per year, and 0.6 L/min/yr, respectively, in the BDP-800 group. In the BDP-1,500 group, there were no statistically significant improvements in FEV(1), PC(20), PEF indexes, and symptom scores after increasing the dose of BDP.

CONCLUSIONS

We conclude that initial improvements in FEV(1), PC(20), and PEF are well preserved over 5 years in patients with obstructive airways diseases who are treated with terbutaline and BDP. In the patients who responded sufficiently to 800 microg/d of BDP, there was no accelerated decline in FEV(1) compared with the general population. Increasing the dose of BDP in a small group of patients with an accelerated fall in FEV(1) (initially treated with a moderate dose of BDP) resulted in no significant improvement in FEV(1), PC(20), PEF indexes, and symptom scores.

Incidence of physician-diagnosed asthma in adults--a real incidence or a result of increased awareness? Report from The Obstructive Lung Disease in Northern Sweden Studies

Only limited data are available about the incidence of asthma based on longitudinal prospective studies. Further, the results from different studies on incidence vary considerably depending on the age composition of the cohorts under study, the used methods and the criteria for disease. Also among adults high incidence rates have been reported during recent years. The aim of this study was to examine to what extent the incidence of physician-diagnosed asthma could be explained by a real incidence of the disease, and to what extend by an increased diagnostic activity or altered diagnostic praxis. Another aim was to study risk factors for asthma based on incident cases. Three cross-sectional surveys have been performed in the same population sample living in the northern-most province of Sweden, Norrbotten. The first survey was performed in 1986, and 5698 subjects, 86% of those invited, responded to a postal questionnaire. Of these, 4754 subjects (83%) participated at the third survey in 1996. After exclusion of all subjects who had reported that they had asthma in 1986, or had been classified as having asthma in 1986, 68 men and 98 women (P=0.02) reported in 1996 that they had been diagnosed as having asthma by a physician. Thus, the cumulative incidence for the 10-year period was 3.2% among men and 4.5% among women. After correction for subjects who already in 1986 had reported symptoms common in asthma, or had been classified as having chronic bronchitis, 97 subjects with incident asthma remained, which corresponded to an annual incidence rate among men of 1.7 and among women of 2.9/1000 persons year(-1) (P=0.1). Clinical examinations confirmed asthma in a large majority of these 97 subjects. Significant risk factors were family history of asthma, both ex- and current smoking, and female sex. The socio-economic groups manual workers and assistant non-manual employees were associated with incident asthma, although not significantly. The increasing prevalence of asthma among adults during recent 10-20 years may to a considerable extent be explained by an increased diagnostic activity or altered diagnostic praxis. Use of different methods when measuring incidence may in part explain the extremely diverging incidence rates of asthma found in different studies.

Occupational airway diseases

In this review we describe characteristics of occupational airway diseases, as well as physical and chemical characteristics of agents inducing airway disease. Occupational airway diseases include industrial bronchitis, reactive airway dysfunction syndrome, bronchiolitis obliterans, and occupational asthma. High- and low-molecular weight substances associated with occupational airway disease are listed. The importance of host factors is stressed. Diagnostic approaches, particularly indicators for specific challenge testing with occupational materials, are described. Preventive and control measures are presented.

Asthma and smoking status in a population-based study of California adults

OBJECTIVE

Because they experience respiratory symptoms, adults with asthma might be expected to avoid cigarette smoking. However, previous studies have not adequately addressed whether adults with asthma have a lower prevalence of smoking than the general population. The authors sought to determine whether adult asthmatics are less likely to smoke cigarettes than members of the general population.

METHODS

The authors used data from a random sample of 2,902 California adults ages 18 years or older,with oversampling of African Americans, Asian/Pacific Islanders, adults with disabilities, and adults aged 45 to 70 years. Sampling weights were used in all analyses. In this cross-sectional study, 217 participants (7.5%) reported a physician diagnosis of asthma.

RESULTS

The prevalence of "ever smoking" was similar among adults with asthma (48.3%) and those without asthma (43.0%) (risk difference 5.3%; 95% CI -1.6%, 12.2%). There was also no difference in the prevalence of "current smoking" among adults with asthma (20.2%) compared with the non-asthmatic subjects (18.8%) (risk difference 1.4%; 95% CI -4.2%, 6.9%). After controlling for age, gender, race, and education, there was no evidence that adults with asthma were less likely to ever smoke. Although the confidence intervals did not exclude "no association," asthma was actually associated with an increased risk of ever smoking (OR 1.3; 95% CI 1.0, 1.8). There was also no association between asthma and the risk of current smoking after controlling for covariates (OR 1.1; 95% CI 0.8, 1.6). Moreover, there were no differences in "age of smoking initiation," "duration of smoking," or "intensity of smoking" after adjusting for demographic characteristics. Redefining the referent group to exclude respondents with other chronic lung diseases did not appreciably change study conclusions.

CONCLUSION

Adults with asthma do not appear to selectively avoid cigarette smoking. Specific smoking prevention and cessation efforts should be targeted to adults with asthma.

Late onset asthma: epidemiology, diagnosis and treatment

Asthma is common among older persons, affecting approximately 4 to 8% of those above the age of 65 years. Despite its prevalence, late onset asthma may be misdiagnosed and inadequately treated, with important negative consequences for the patient's health. The histopathology of late onset disease appears to be similar to that of asthma in general, with persistent airway inflammation a characteristic feature. It is less clear, however, that allergic exposure and sensitisation play the same role in the development of disease in adults as they do in children. Atopy is less common among those with late onset asthma, and the prevalence of elevated immunoglobulin E levels is lower among those aged over 55 years of age than younger patients. Occupational asthma is an aetiological consideration unique to adult onset disease, with important implications for treatment. The differential diagnosis for cough, wheeze, and dyspnoea in the elderly is broad, and includes chronic obstructive bronchitis, bronchiectasis, congestive heart failure, lung cancer with endobronchial lesion and vocal cord dysfunction. Keys to accurate diagnosis include a good history and physical examination, the demonstration of reversible airways obstruction on pulmonary function tests and a favorable response to treatment. Inhaled corticosteroid therapy is recommended for patients with persistent disease, and careful instruction in the use of metered-dose inhalers is particularly important for the elderly.

A simulation of the effects of youth initiation policies on overall cigarette use

OBJECTIVES

We developed a simulation model to predict the effects of policies aimed at reducing smoking initiation by youths younger than 18 years.

METHODS

The model projected the number of smokers, never smokers, and ex-smokers by age, sex, and racial/ethnic group and the effects of reductions in youth initiation.

RESULTS

The model predicted that even if tobacco policies eliminated youth initiation, the number of smokers would not be halved for more than 30 years. If initiation were halved and some of the initiation were delayed rather than eliminated, substantially smaller reductions would result.

CONCLUSIONS

Policies that increase cessation rates are needed to reduce the number of current smokers and the more near-term health problems.

Predictors of cigarette smoking and smoking cessation among adults with asthma

OBJECTIVES

This study sought to determine the predictors of smoking and time until smoking cessation in a cohort of adults with asthma.

METHODS

Adults with asthma (n = 374) in northern California completed structured telephone interviews at baseline and 18-month follow-up.

RESULTS

Of the 374 subjects, 156 reported ever having smoked, and 39 indicated that they currently smoked. Earlier birth cohort, lower educational attainment. White race, and presence in childhood residence of an adult who smoked were associated with a greater risk of ever smoking. Lower educational attainment, early smoking initiation, higher daily cigarette consumption, and late-childhood-onset asthma were associated with a longer interval until smoking cessation.

CONCLUSIONS

Persons with asthma at high risk of cigarette smoking and delayed quitting can be identified on the basis of clinical and demographic characteristics.

Consequences of long-term inflammation. Airway remodeling

Airway inflammation may not account for all the clinical manifestations of asthma. Airway remodeling, which is thought to be a result of airway chronic inflammation, may help fill this void. Remodeling is described for fatal and nonfatal asthmatics including changes in smooth muscle, collagen deposition, noncollagenous matrix, and mucus glands. This article also reviews the correlation of airway remodeling with clinical, physiologic and biologic data, experimental models of airways remodeling, and effect of therapy on airway remodeling. Throughout, it is emphasized that the concept of airway remodeling is a dynamic process that is active and potentially progressive in asthmatic patients but that may be prevented by appropriate therapy.

Asthma from childhood to adulthood: course and outcome of lung function

Lung function (FEV1 before and after bronchodilatation) was studied prospectively over five visits in 55 asthmatic children (28 boys) from childhood to adulthood (age 30). At the last follow-up recordings were made at rest, after cold air challenge (CACh), and after bronchodilatation. Results were related to clinical asthma scoring and to sensitization to furred animals, as described in a companion paper. Lung function outcome was shown to be influenced by initial FEV1 (% predicted) and gender, but not by initial asthma severity or sensitization. FEV1 (% predicted) was higher in females than in males over the first two follow-ups, but the reverse was found over the subsequent visits. It deteriorated from childhood to adulthood in the females but improved in the males. In adulthood the females (for height 170 cm) had a steeper normalized annual fall in post-bronchodilator FEV1 than the males (55 +/- 38 vs. 25 +/- 36 ml; P = 0.006). The degree of bronchial hyperresponsiveness was associated significantly with asthma severity and the extent of sensitization to furred animals, but not with gender. The results indicate a better lung function outcome for asthmatic boys than for girls, confirming trends seen in clinical asthma severity. In adulthood the extent of sensitization to relevant perennial inhaled allergens significantly influences airway responsiveness and asthma severity, but not lung function.

Asthma: A disease of inflammation and repair

Mucosal inflammation and more recently airway remodeling continue to be a focus of interest when considering both the pathophysiology and treatment of asthma. Although a number of candidate genes relevant to inflammatory cell action have been identified and linked to atopy and airway hyperresponsiveness, it is important to understand genetic factors that might determine the extent of tissue remodeling. The mechanisms regulating the allergic responses in the airways are complex, involving antigen presenting cells and T lymphocytes, which process antigens and orchestrate the response, and mast cells and eosinophils as effector cells. Abundant evidence also points to a proinflammatory role for structural cells, including epithelial and endothelial cells, and smooth muscle. Because of the complex nature of the inflammatory changes in asthma, the exact relation between individual inflammatory cells and their mediators on the one hand and hyperresponsiveness of the airways and clinical manifestations on the other remains unclear. The same applies to the phenomenon of airway remodeling because it is uncertain exactly how the different components of restructuring affect the airway physiology. If progress is to be made in the treatment of asthma, further efforts will be needed to understand the regulation and link between the mechanisms causing inflammation and those leading to fibrotic changes.

Natural history of chronic asthma and its long-term effects on pulmonary function

Although asthma is a disease that has intrigued physicians since antiquity, its natural history has been incompletely determined. It has long been held that the presence of asthma, per se, does not carry with it any long-term deterioration in lung function, but recently this view has been challenged, and it has become fashionable to define asthma as being only partially reversible. At present, there are limited data to support such a view. All of the available information indicates that the vast majority of patients do not experience the development of a progressive decline in pulmonary mechanics or appear to be at risk for a diminution in life expectancy.

Is there a relationship between smoking and asthma in adults?

A case-control study was carried out to investigate the possibility of a relationship between smoking and asthma in adults. The study group of 141 asthmatic adults and 423 age- and sex-matched non-asthmatic controls were selected from 4341 men and women aged 18 years and over, who were registered with a family practice. Both groups were interviewed by telephone about past and present smoking habits. Current smokers constituted 22% of the asthmatic group and 15% of the controls (not significantly different). The prevalence of those who had given up smoking (quitters) was significantly higher in asthmatics than in controls (8.5% versus 3.6%). Asthma began at younger ages in smokers than in quitters and non-smokers. In smokers, the duration of smoking was associated with the duration of asthma. No other significant differences in or associations between smoking habits and asthma were found. No major relationship between smoking and asthma was demonstrated.

Effects of inhaled corticosteroids on the consequences of asthma

Asthma is a chronic inflammatory disease of the airways involving a characteristic pattern of airway infiltration with lymphocytes, eosinophils, and mast cells, subepithelial deposition of collagen, and hypertrophy and hyperplasia of smooth muscle and of goblet cells and submucosal glands. The consequences of this chronic process include episodic or persistent symptoms, bronchial hyperreactivity, attacks of bronchoconstriction that may require emergency care or hospitalization and can lead to death, impairment in quality of life, and the development of irreversible airflow obstruction. Careful pathologic studies have shown that inhaled corticosteroid therapy can reverse or suppress airway inflammation, and prospective controlled clinical trials have proven that it can also improve symptoms, reduce bronchial hyperreactivity, and reduce the frequency and severity of attacks. It is also highly likely, although it is not yet proven, that inhaled corticosteroid therapy reduces the risk of asthma fatality and prevents or retards airway wall remodeling. These beneficial effects are easily shown in patients with moderate or severe asthma. Although inhaled corticosteroid therapy also benefits patients with mild asthma, it is less certain that the costs and risks of continuous therapy are justified. For these patients, the most important issues that remain to be resolved are the nature of the risk of development of permanent airflow obstruction and the effects of early, sustained treatment on the chances of sustained remission of asthma after all therapy has been stopped.

The natural history of asthma

Our understanding of the natural history of asthma is improving through the establishment of a more precise definition of asthma linked with information from large-scale longitudinal studies. Risk factors for the development of childhood asthma including sex, atopic status, genetic and familial factors, respiratory infections, and outdoor and indoor pollution are now more clearly understood. New information on the relation of viral wheezing episodes in infancy to later childhood asthma is evolving. We now know that children who start wheezing early in life and continue to wheeze at age 6 years are more likely to have a maternal history of asthma, elevated serum IgE levels, and normal lung function in the first year of life. However, at age 6 years they have both elevated serum IgE levels and diminished lung function. Approximately 50% of adults who report having had childhood asthma no longer have symptoms. Airway responsiveness in childhood tends to predict airway responsiveness in adulthood and to be greater in asthmatics with persistent symptoms. Studies of the natural history of asthma support the hypothesis that early therapeutic intervention in mild disease may lead to an improved clinical outcome. Adults exposed to specific occupational environments are at additional risk for the development of asthma. As we learn more about the natural history of asthma, we will have a better understanding of the effect of early diagnosis, environmental control, and therapy on the outcome of the disease.

Airways obstruction in patients with long-term asthma consistent with 'irreversible asthma'

OBJECTIVE

To describe a series of eight patients with long-term asthma and pulmonary function consistent with "end-stage," irreversible obstruction.

DESIGN

Retrospective descriptive analysis of patients with severe asthma.

SETTING

A university-based allergy-immunology service with a large population of corticosteroid-dependent patients with asthma.

PATIENTS

Eight patients with long-standing asthma and apparently irreversible airways obstruction despite long-term oral and inhaled corticosteroid therapy.

MEASUREMENTS

Pulmonary function data, radiographic studies including chest radiograph and high-resolution CT of the chest, and serologic analysis to rule out allergic bronchopulmonary aspergillosis and alpha1-antitrypsin deficiency had been performed as indicated, and these results were obtained through chart review.

RESULTS

The age of the patients ranged from 41 to 58 years, with a mean duration of asthma of 39 years (SD = 12.4 years). No patient had evidence of any other pulmonary disease process. The mean duration of daily or alternate-day oral corticosteroid treatment was 15.8 years (SD=11.8 years). Despite intensive pharmacotherapy, all patients had an FEV1 57% (42+/-12%) with marked small airways disease as reflected in the forced expiratory flow between 25% and 75% of the FVC. Three of the eight patients demonstrated an accelerated decline in FEV1 despite continuous systemic corticosteroids.

CONCLUSIONS

We have described a series of eight patients with long-standing asthma who demonstrate irreversible airways obstruction despite long-term systemic and inhaled corticosteroids. The term "end-stage asthma" or irreversible asthma might be applied to these patients in whom fixed obstruction has occurred in the absence of other pulmonary diseases.

Incidence of asthma in adults--report from the Obstructive Lung Disease in Northern Sweden Study

Incidence studies offer a better opportunity to study risk factors for asthma than do prevalence studies. However, regular prospective follow-ups of large cohorts are difficult to perform, and that is why direct measurement of the incidence rate of asthma is almost impossible. Thus, cross-sectional follow-up studies of defined cohorts can be used to provide data on incidence. In 1986, a postal questionnaire survey on respiratory symptoms and diseases was performed in the northernmost province of Sweden. The population sample comprised all subjects born in 1919-20, 1934-5, and 1949-50 in eight representative areas of the province, which comprises 25% of the total area of Sweden. Completed answers were given by 5698 subjects (86%) of the 6610 subjects invited to the study. In 1992, the cohort was invited to a follow-up survey during the same season as in 1986, and 6215 subjects were traced. Of the 5393 subjects who answered the questionnaire, 4932 had participated in the 1986 survey, or 87% of those who participated in 1986. For the period 1986-92, the cumulative incidences of asthma were 4.9 and 5.0%, respectively, as assessed by the questions, "Have you ever had asthma?" and "Have you been diagnosed as having asthma by a physician?" Thus, the results indicate a mean annual cumulative incidence of asthma of 0.8%. After correction of the results for subjects who were diagnosed as having asthma in the clinical part later in the 1986 study, the mean annual cumulative incidence of asthma was found to be 0.5%. Risk factors were family history of asthma (OR 3.46) and current and former smoking, while female sex was a strong trend.

Longitudinal decline in lung function in patients with occupational asthma due to western red cedar

BACKGROUND

There are few reports about longitudinal changes in lung function in asthmatic patients. Patients with asthma had a greater loss of lung function than normal healthy adults. To date, there have been no studies about the longitudinal changes in lung function in patients with occupational asthma.

METHODS

280 male patients with red cedar asthma (RCA) who were followed up for at least one year were the study group. The exposed controls consisted of 399 male sawmill workers. Forced expiratory volume in one second (FEV1) was measured with a Collins water spirometer. Changes in FEV1 over time (FEV1 slope) were calculated by a two point method for each subject. Atopy was considered to be present if the subjects showed at least one positive response to three allergens by skin prick test.

RESULTS

Multiple regression analysis was carried out to examine factors that might affect longitudinal decline in FEV1. Patients with RCA who were still exposed had a greater decline in FEV1 slope (-26 ml/y) than sawmill workers. Smokers also showed a greater rate of decline in FEV1 (-43 ml/y) than non-smokers.

CONCLUSIONS

Patients with RCA who continued to be exposed had a greater rate of decline in FEV1 than sawmill workers. Early diagnosis of occupational asthma and removal of these patients from a specific sensitiser is important in the prevention of further deterioration of lung function and respiratory symptoms.

Respiratory symptoms and lung function in wool textile workers

Our study investigated a group of 216 wool textile workers (158 women and 58 men). Respiratory symptoms were assessed by questionnaire in wool textile workers and in 130 not exposed (control) workers. Ventilatory capacity was measured in wool workers by recording maximum expiratory flow-volume (MEFV) curves on Monday before and after the work shift. Forced vital capacity (FVC), 1-second forced expiratory volume (FEV1), and flow rates at 50% and the last 25% of the vital capacity (FEF50, FEF25) were measured on the MEFV curves. Analysis of the data demonstrated a significantly higher prevalence of all chronic respiratory symptoms in wool workers than in controls, being the highest in wool workers for nasal catarrh (M: 63.8%; F: 44.9%) and for sinusitis (M: 62.1%; F: 43.0%). A high prevalence of acute symptoms, associated with the work shift, was also noted in wool workers. Exposure to wool dust caused significant across-shift reductions of ventilatory capacity varying from 1.4% for FEV1 to 9.1% for FEF50. Textile workers exposed to wool for > 10 years in the workplace had similar across-shift reductions of ventilatory capacity tests as those with shorter exposures. In a large number of these wool workers, FEF50 and FEF25 were below 70% of predicted normal values. Smokers had acute and chronic lung function changes similar to those of nonsmokers, indicating that smoking did not account for all the respiratory effects seen in wool processing workers. Our data suggest that dust exposures in wool textile mills may be associated with the development of chronic respiratory symptoms and impaired lung function.

Long-term survival of a cohort of community residents with asthma

BACKGROUND

Reports of an increase in asthma-related mortality have been based on studies of death certificates from the general U.S. population on which asthma was listed as an underlying cause of death. We addressed the issue in a different way by analyzing long-term survival in a defined, population-based cohort of patients with asthma.

METHODS

We identified all residents of Rochester, Minnesota, in whom asthma was diagnosed from January 1, 1964, through December 31, 1983, by reviewing the medical records of all patients with asthma and associated diagnoses, using explicit predefined criteria. The patients' vital status at last follow-up was ascertained. Medical records, death certificates, and autopsy reports were reviewed to classify deaths as due either to asthma or to other conditions.

RESULTS

We identified 2499 patients with definite or probable asthma. The mean duration of follow-up was 14 years (range, 0 to 29). There were 140 deaths during 32,605 person-years of follow-up. Overall survival was not significantly different from the survival that was expected for residents of Rochester. Survival was less than expected in patients who were 35 years of age or older when their asthma was diagnosed and who also had another lung disease (predominantly chronic obstructive pulmonary disease). Four percent of all deaths in the study cohort were due to asthma, and all were among adults. Survival was not related to the year of onset of asthma.

CONCLUSIONS

Survival among patients with asthma but no other lung disease was not significantly different from expected survival. However, patients 35 or older who had asthma associated with chronic obstructive pulmonary disease did have worse than expected survival. Asthma was classified as the cause of death in only 4 percent of the patients, and there was no evidence of an increased risk of death among patients with a more recent diagnosis of asthma. These results provide assurance that community-based patients with asthma usually have a good prognosis.