The role of allergy and nonspecific airway hyperresponsiveness in the pathogenesis of chronic obstructive pulmonary disease

Comprehensive Cluster Analysis for COPD Including Systemic and Airway Inflammatory Markers

Chronic obstructive pulmonary disease (COPD) is a complex, multidimensional and heterogeneous disease. The main purpose of the present study was to identify clinical phenotypes through cluster analysis in adults suffering from COPD. A retrospective study was conducted on 178 COPD patients in stable state recruited from ambulatory care at University hospital of Liege. All patients were above 40 years, had a smoking history of more than 20 pack years, post bronchodilator FEV1/FVC <70% and denied any history of asthma before 40 years. In this study, the patients were described by a total of 84 mixed sets of variables with some missing values. Hierarchical clustering on principal components (HCPC) was applied on multiple imputation. In the final step, patients were classified into homogeneous distinct groups by consensus clustering. Three different clusters, which shared similar smoking history were found. Cluster 1 included men with moderate airway obstruction (n = 67) while cluster 2 comprised men who were exacerbation-prone, with severe airflow limitation and intense granulocytic airway and neutrophilic systemic inflammation (n = 56). Cluster 3 essentially included women with moderate airway obstruction (n = 55). All clusters had a low rate of bacterial colonization (5%), a low median FeNO value (<20 ppb) and a very low sensitization rate toward common aeroallergens (0-5%). CAT score did not differ between clusters. Including markers of systemic airway inflammation and atopy and applying a comprehensive cluster analysis we provide here evidence for 3 clusters markedly shaped by sex, airway obstruction and neutrophilic inflammation but not by symptoms and T2 biomarkers.

Revisiting the Dutch hypothesis

The Dutch hypothesis was first articulated in 1961, when many novel and advanced scientific techniques were not available, such as genomics techniques for pinpointing genes, gene expression, lipid and protein profiles, and the microbiome. In addition, computed tomographic scans and advanced analysis techniques to dissect (small) airways disease and emphysema were not available. At that time, the group of researchers under the visionary guidance of Professor N. G. M. Orie put forward that both genetic and environmental factors can determine whether one would have airway obstructive diseases, such as asthma and chronic obstructive pulmonary disease (COPD). Moreover, they stipulated that the phenotype of obstructive airway disease could be affected by sex and changes with aging. Orie and colleagues' call to carefully phenotype patients with obstructive airways diseases has been adopted by many current researchers in an attempt to determine the heterogeneity of both asthma and COPD to better define these diseases and optimize their treatment. The founders of the Dutch hypothesis were far ahead of their time, and we can learn from their insights. We should fully characterize all patients in our clinical practice and not just state that they have asthma, COPD, or asthma and COPD overlap syndrome. This detailed phenotyping can help in understanding these obstructive airway diseases and provide guidance for disease management.

Longitudinal assessment of airway responsiveness from 1 month to 18 years in the PIAF birth cohort

The Perth Infant Asthma Follow-up (PIAF) study involves a birth cohort of unselected subjects who have undergone longitudinal assessments of airway responsiveness at 1, 6 and 12 months and 6, 11 and 18 years of age. The aim of this study was to determine the relationship between increased airway responsiveness throughout childhood and asthma in early adult life.Airway responsiveness to histamine, assessed as a dose-response slope (DRS), and a respiratory questionnaire were completed at 1, 6 and 12 months and 6, 11 and 18 years of age.253 children were initially recruited and studied. Airway responsiveness was assessed in 203, 174, 147, 103, 176 and 137 children at the above-mentioned time points, respectively (39 participants being assessed on all test occasions). Asthma at 18 years was associated with increased airway responsiveness at 6, 12 and 18 years, but not during infancy (slope 0.24, 95% CI 0.06-0.42; p=0.01; slope 0.25, 95% CI 0.08-0.49; p=0.006; and slope 0.56, 95% CI 0.29-0.83; p<0.001, respectively).Increased airway responsiveness and its association with asthma at age 18 years is established between infancy and 6 years. We propose that airway responsiveness in early life reflects the initial airway geometry and airway responsiveness later in childhood increasingly reflects immunological responses to environmental influences.

The prevalence of increased serum IgE and Aspergillus sensitization in patients with COPD and their association with symptoms and lung function

Background

Allergy and Aspergillus hypersensitivity (AH) were shown to be associated with severe symptoms or worse lung function in COPD patients. The prevalence of elevated total IgE (T-IgE) and its association with clinical symptoms and lung function in COPD have not been studied. The prevalence of AH and its correlation with clinical characteristics in a COPD cohort of larger sample size is also lacking.

Methods

273 patients with COPD were evaluated by respiratory symptoms, blood test, chest HRCT, lung function, serum detection of T-IgE and Aspergillus specific IgE. Patients with T-IgE ≥ 1000 KU/L were further investigated for allergic bronchopulmonary aspergillosis (ABPA).

Results

The prevalence of elevated T-IgE and AH in patients with COPD was 47.3% and 15.0%, respectively. Eight patients (2.9%) met the diagnostic criteria for ABPA. Compared with the normal T-IgE group, patients with elevated T-IgE had a longer history of dyspnea (p < 0.01), an earlier onset of dyspnea after chronic cough/expectoration (p < 0.01), and were more likely to wheeze (p < 0.01). They also showed worse lung functions and more severe GOLD staging (p < 0.01). Analysis of the clinical data in male patients with smoking as the risk factor showed the same results. To evaluate the clinical characteristics of COPD with AH, patients with elevated T-IgE were further divided into subgroups with and without AH. When compared with the normal T-IgE group, both the two subgroups showed longer history of dyspnea (p < 0.01), an earlier onset of dyspnea (p < 0.01) and a worse status of lung function (p < 0.05). Correlation analysis demonstrated that T-IgE was correlated positively with the time length of dyspnea (r = 0.401, p < 0.001), and the ratio of duration of dyspnea to that of chronic cough/expectoration (r = 0.59, p < 0.001), but negatively with FEV1/FVC% (r = −0.194, p = 0.001), and FEV1%predicted (r = −0.219, p < 0.001).

Conclusions

There was a high prevalence of elevated serum T-IgE and AH in patients with COPD. Serum T-IgE level was correlated with symptoms such as dyspnea and impairment of lung function. Allergens other than Aspergillus may have similar effects on disease expression or progression of COPD.

Association of chronic nasal symptoms with dyspnoea and quality-of-life impairment in chronic obstructive pulmonary disease

BACKGROUND AND OBJECTIVE

Previous studies suggested that chronic nasal symptoms (CNS) are frequent in chronic obstructive pulmonary disease (COPD) subjects, but their contribution to dyspnoea and quality-of-life (QoL) impairment is not clearly established.

METHODS

Data from the French COPD cohort 'Initiatives bronchopneumopathie chronique obstructive' were analyzed to assess the frequency of CNS (rhinorrhea, obstruction, anosmia) in COPD patients and analyze their impact and associated risk factors. Univariate and multivariate analyses were performed to assess the relationship between CNS with sociodemographic and anthropometric characteristics, risk factors, respiratory symptoms, spirometry, QoL (Saint George's respiratory questionnaire (SGRQ)), dyspnoea (modified Medical Research Council (mMRC) scale), mood disorders (Hospital Anxiety and Depression Scale (HADS)), number of exacerbations and comorbid conditions.

RESULTS

CNS were reported by 115 of 274 COPD subjects (42%). Among them, rhinorrhea and nasal obstruction were reported by 62% and 43%, respectively. In multivariate analysis, COPD patients with CNS had higher SGRQ total scores, corresponding to worse QoL (P = 0.01), while no independent association was found with exacerbations, lung function and HADS. Among SGRQ domains, an independent association was found with the activity score (P = 0.007). When SGRQ score was forced out of the model to avoid redundancy, mMRC score was independently associated with CNS (P = 0.01). Among risk factors, cumulative smoking, hay fever and atopic dermatitis but not occupational exposures were independently associated with CNS.

CONCLUSIONS

In this group of COPD subjects, CNS were frequently observed and associated with dyspnoea and poorer QoL. CNS should be systematically assessed and could be a potential target in the management of COPD.

Variations in FEV₁ decline over time in chronic obstructive pulmonary disease and its implications

PURPOSE OF REVIEW

This article reviews findings from longitudinal observational studies in both general and chronic obstructive pulmonary disease (COPD) populations, as well as from intervention trials in COPD, in which the annual rate of decline in forced expired volume in 1  s (FEV₁) has been measured. The purpose of the review is to describe the individual variability in rates of decline in FEV₁ within these populations, explore the factors contributing to this variability and discuss its implications.

RECENT FINDINGS

Individual rates of decline in FEV₁ have been found to vary considerably across participants with COPD in both observational cohorts and intervention trials from decreases as rapid as 150-200  ml per year to increases of up to approximately 150  ml per year, with mean rates of decline ranging from 33 to 69  ml per year. Aside from technical and biologic (e.g., time of day, season, weather, fatigue) sources of variation, other influential factors have included smoking status (most notably current versus former smoking), baseline smoking intensity, baseline lung function, airway hyperresponsiveness, exacerbation frequency, and, variably, age and sex. The presence of emphysema may also be a determinant, as well as certain biomarkers and gene variants.

SUMMARY

The wide distribution of individual rates of decline in FEV₁ includes especially rapid and slow declines. Future research is needed to identify biomarkers that both are predictive of a rapid decline within individuals who might then be targeted for special intervention and might also serve as surrogate endpoints in interventional trials.

Association between occupational exposure and the clinical characteristics of COPD

Background

The contribution of occupational exposures to COPD and their interaction with cigarette smoking on clinical pattern of COPD remain underappreciated. The aim of this study was to explore the contribution of occupational exposures on clinical pattern of COPD.

Methods

Cross-sectional data from a multicenter tertiary care cohort of 591 smokers or ex-smokers with COPD (median FEV1 49%) were analyzed. Self-reported exposure to vapor, dust, gas or fumes (VDGF) at any time during the entire career was recorded.

Results

VDGF exposure was reported in 209 (35%) subjects aged 31 to 88 years. Several features were significantly associated with VDGF exposure: age (median 68 versus 64 years, p < 0.001), male gender (90% vs 76%; p < 0.0001), reported work-related respiratory disability (86% vs 7%, p < 0.001), current wheezing (71% vs 61%, p = 0.03) and hay fever (15.5% vs 8.5%, p < 0.01). In contrast, current and cumulative smoking was less (p = 0.01) despite similar severity of airflow obstruction.

Conclusion

In this patient series of COPD patients, subjects exposed to VDGF were older male patients who reported more work-related respiratory disability, more asthma-like symptoms and atopy, suggesting that, even in smokers or ex-smokers with COPD, occupational exposures are associated with distinct patients characteristics.

Prevalence of allergic diseases and risk factors of wheezing in Korean military personnel

The objective of this study was to evaluate the prevalence of asthma, allergic rhinitis, and atopic dermatitis, as well as the risk factors of wheezing among young adults in the Korean military. Young military conscripts in five areas completed a modified International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire. For subjects with current wheeze in one sample area, baseline spirometry and bronchodilator response were measured. For subjects without a significant response to bronchodilator (improvement in FEV1 of more than 200 mL and 12%), methacholine challenge tests (MCT) were also performed. Of 3,359 subjects that completed the questionnaire, 354 (10.5%) had current wheeze, 471 (14.0%) had current allergic rhinitis, and 326 (9.7%) had current eczema. Current wheeze was associated with family history of allergic disease, overweight, current smoking, allergic rhinitis, and atopic dermatitis. Of 36 subjects with current wheeze who underwent PFT with or without MCT in the Anyang area, 24 (66.7%) were confirmed to have current asthma. In conclusion, the prevalence of allergic disease in young adults of Korean military is not low, and the risk factors of wheezing include family history of allergic disease, overweight, current smoking, allergic rhinitis, and atopic dermatitis.

Lung function and airway diseases

Two studies report genome-wide association studies for lung function, using cross-sectional spirometric measurements in healthy individuals. They identify six genetic loci newly associated to natural variation in lung function, which may have implications for the related airway diseases of asthma and chronic obstructive pulmonary disease.

Altered pulmonary function in children with asthma associated with highway traffic near residence

Cross-sectional analyses were conducted to evaluate the effects of exposure to highway traffic on pulmonary function in Fresno, California. Traffic and spirometry data were available for 214 children (enrollment ages six to 11 years). Multiple linear regression was used to evaluate the relations between pulmonary function and traffic parameters. Heavy-duty vehicle count was used as a surrogate measure for diesel-related exposures. Pulmonary function was non-significantly associated with longer distance-to-road and non-significantly associated with higher traffic intensity. Evaluation of effect modification by FEF(25-75)/FVC (a measure of intrinsic airway size) showed that all pulmonary function measures of flow were significantly inversely related to a traffic metric that incorporates traffic intensity and roadway proximity. The results indicate that residence proximity to highway traffic is associated with lower pulmonary function among children with asthma, and smaller airway size is an important modifier of the effect of traffic exposure on pulmonary function and a marker of increased susceptibility.

Induced sputum and peripheral blood cell profile in chronic obstructive pulmonary disease

OBJECTIVE

To determine cell profiles, as well as to identify CD4+ and CD8+ lymphocyte subgroups, in induced sputum (IS) and peripheral venous blood (PVB) of patients with chronic obstructive pulmonary disease (COPD).

METHODS

Total cell counts and counts of individual cell types, including CD4+ and CD8+ T lymphocytes, were determined in the IS and PVB of 85 subjects (38 with COPD without exacerbation, 29 smokers without obstruction and 18 nonsmokers). Mann-Whitney and Spearman non-parametric tests were used in the statistical analysis, and values of p < 0.05 were considered statistically significant.

RESULTS

Comparing the IS of subjects with COPD to that of nonsmokers, neutrophil, eosinophil and CD8+ T lymphocyte counts were higher (respectively p = 0.005, p < 0.05 and p < 0.05), whereas the percentage of macrophages was lower (p = 0.003). There were weak linear correlations (r(2) < 0.1) between each cell type in IS and forced expiratory volume in one second (FEV1), forced vital capacity (FVC) and FEV1/FVC ratio. Eosinophil and CD8+ T lymphocyte counts were also higher in PVB (p = 0.04 and p = 0.02).

CONCLUSIONS

In patients with stable COPD, CD8+ T lymphocyte counts were higher in PVB, whereas total leukocyte counts were similar to those of the other two groups analyzed, suggesting systemic inflammatory involvement. The CD8+ T lymphocyte count in blood can be a useful marker of systemic inflammation and can help identify smokers who already present a COPD inflammatory pattern.

Airway responsiveness in mild to moderate childhood asthma: sex influences on the natural history

RATIONALE

Airway responsiveness is a prognostic marker for asthma symptoms in later life.

OBJECTIVES

To evaluate characteristics responsible for persistence of airway responsiveness in children with asthma.

METHODS

A total of 1,041 children, initially aged 5-12 years, with mild to moderate persistent asthma enrolled in the Childhood Asthma Management Program (CAMP) were studied prospectively for 8.6 +/- 1.8 years with methacholine challenges yearly.

MEASUREMENTS AND MAIN RESULTS

Least squares geometric mean models were fit to determine effects of sex and age on airway responsiveness (provocative concentration producing 20% decrease in FEV(1) [PC(20)]). Multiple linear regression analysis was performed to determine factors at baseline and over time, which were associated with PC(20) at end of follow-up. A total of 7,748 methacholine challenges were analyzed. PC(20) increased with age, with boys having greater increase after age 11 years than girls (P < 0.001). The divergence coincided with the mean age for Tanner stage 2. Postpubertal girls had greater airway responsiveness, even after adjustment for FEV(1) and other potential confounders. Although multivariable regression analyses noted a variety of factors that influenced airway responsivness in both sexes, a history of hay fever (beta= -0.30, P = 0.005), respiratory allergy (beta= -0.32, P = 0.006), or recent inhaled corticosteroid usage (beta= -0.18, P = 0.02) were associated with decrements in final log PC(20) only in girls.

CONCLUSIONS

Airway responsiveness (PC(20)) is more severe in the postpubertal female with asthma than in males. Although there are factors associated with airway responsiveness in both males and females, sex-specific factors may contribute to new insights into asthma pathogenesis.

Influence of occupational factors on lung function in French dairy farmers. A 5-year longitudinal study

BACKGROUND

Dairy farming is associated with a high prevalence of respiratory disorders but the respective influence of occupational exposures, environmental, and individual factors on lung function remain unclear.

METHODS

In 1994 and 1999, dairy farmers were examined in the Doubs province, France. Spirometric measures and allergological tests were performed. Medical and professional data were obtained by questionnaires. A multiple linear regression analysis was performed.

RESULTS

An accelerated decline in lung function parameters was associated with age, male sex, traditional farm (as opposed to modern farms), and a high rate of total IgE (P < 10(-2)). Blood oxygen saturation (SpO2) was significantly positively linked with the modernization of the farm and negatively with age, smoking status, and log IgE (P < 10(-2)). Geographical factors (altitude and climatic conditions) had no significant effect.

CONCLUSIONS

The modernization of the farm has an important and beneficial impact on lung functiony.

Determinants of bronchial hyperresponsiveness in subjects with rhinitis

Subjects with rhinitis but without asthma may have coexisting bronchial hyperresponsiveness, although the reasons for this are uncertain. To evaluate the factors that determine BHR in rhinitis we examined 410 patients with symptomatic rhinitis with forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC)>or=80% of the predicted value. In all subjects a skin prick test (SPT) was performed, a determination of total serum IgE and an eosinophils count in the blood. Of the 410 subjects we found that 161 (39.3%) exhibited a methacholine PD20 of 800 mg or less (Group A), whereas 249 (60.7%) had a methacholine PD20 more of 800 mg (Group B). Despite the matched mean values for FEV1 and FVC, compared with Group B, Group A had a lower predicted forced expiratory flow between 25% and 75%(FEF25%-75%) (86.7 +/- 12.0 vs. 93.7 +/- 7.3, P < 0.0001). A great portion of the subjects of the Group Ain respect to subjects of the Group B were exposed to passive smoke (37.8% vs. 22.0%, P = 0.0008), reported having mothers with asthma (34.1% vs. 6.0%, P < 0.0001), presented a positive skin prick test (93.7% vs. 67.0%, P < 0.0001), had higher levels of total serum IgE (geometric mean of Log10 2.46 +/- 0.27 kU/L vs. 2.06 +/- 0.38 kU/L, P < 0.0001) and higher blood eosinophil counts (geometric mean of Log10 2.67 +/- 0.07 x 10(-3) mL vs. 2.57 +/- 0.09 x 10(-3) mL, P < 0.0001), and reported increased nasal obstruction (2.0 (95% CI 1.8 to 2.2) vs. 0.6 (95% CI 0.5 to 0.7), P < 0.0001). Logistic regression demonstrates that nasal obstruction (OR 2.19, 95% CI 1.72 to 2.80) and the presence of positive SPT (OR 6.15, 95% CI 2.42 to 15.61) were the most available predictors to discriminate between subjects with BHR and subjects without BHR. In addition, BHR was positively related to blood eosinophil counts (OR= 2.80, 95% CI 1.54 to 5.07), FEF25%-75% values (OR= 2.72, 95% CI 1.23 to 5.99) and familiarity (mother) for asthma (OR = 2.45, 95% CI 1.10 to 5.46). Whereas passive smoke and total serum IgE were not positively related to BHR. Increased nasal obstruction and the presence of positive SPT were the most available predictors to discriminate between subjects with and without BHR. Finally, BHR was positively related to blood eosinophil counts, FEF25%-75% values and to familiarity (mother) for asthma.

Asthma: diagnosis and management

The diagnosis and management of asthma continue to be of critical importance, as recent trends have demonstrated its increasing prevalence, morbidity, and perhaps mortality. Because current treatments for asthma are effective and safe, it is important to diagnose asthma early and to use treatments effectively, particularly those directed toward airway inflammation. The diagnostic measures and array of medications, both those currently available and on the horizon, provide an armamentarium for effective diagnosis, management, and monitoring of asthma. In the coming years, it is expected that additional testing modalities will be available for more precise monitoring of asthma control, and an increased understanding of pharmacogenetics will enable the tailoring of asthma medications to specific patients, providing customized therapy to maximize asthma control.

Gender and chronic obstructive pulmonary disease in high-risk smokers

BACKGROUND

Data suggest that women are more susceptible to develop airway obstruction compared to men for the same number of cigarettes smoked.

OBJECTIVES

To compare the prevalence of chronic obstructive lung disease (COPD) and the effect of smoking on the risk of developing COPD according to gender, in a population of high-risk smokers.

METHODS

In 795 smokers, spirometry was performed using the criteria of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) to determine airflow obstruction. COPD prevalence was determined in smokers grouped according to the number of cigarettes smoked per year [<20 (I), 20-40 (II), 40-60 (III) and >60 pack-years (IV)] and age.

RESULTS

Men were older, smoked more and for a longer period. Age at smoking initiation and the number of packs smoked per day did not differ. COPD was diagnosed in 26% of the subjects (30.5% men and 22.3% women, p < 0.001) with similar degree of obstruction (forced expiratory volume in 1 s: 78% of predicted in men vs. 75% in women). COPD prevalence was lower in women in all categories irrespective of the pack-year history (I: 9 vs. 19%; II: 16 vs. 28%; III: 28 vs. 39%, and IV: 25 vs. 42%, respectively, p < 0.001). In those older than 50 years, 34% men and 17% women (p < .001) had COPD.

CONCLUSIONS

Using the GOLD criteria, the prevalence of COPD in smokers was higher than previous reports. In this self-selected sample of high-risk smokers having the same smoking history, prevalence was lower in women than in men, suggesting a lower susceptibility for the development of airway obstruction.

[Association between the forced midexpiratory flow/forced vital capacity ratio and bronchial hyperresponsiveness]

OBJECTIVE

A long-standing hypothesis is that a low ratio of airway caliber to lung size is associated with bronchial hyperresponsiveness (BHR). The aim of our study was to measure the association between airway caliber relative to lung size (expressed as the ratio between forced expiratory flow, midexpiratory phase, divided by forced vital capacity [FEF(25%-75%)/FVC]) and BHR measured by a methacholine challenge test, adjusting for age, height, sex, smoking history, geographic area, respiratory symptoms, and baseline forced expiratory volume in 1 second (FEV1).

MATERIAL AND METHODS

We carried out a multicenter cross-sectional study of the general Spanish population in 2647 subjects from the European Community Respiratory Health Survey (ECRHS I). The ECRHS questionnaire was administered, total and specific immunoglobulin E were measured, and skin tests, spirometry, and a methacholine challenge test were performed.

RESULTS

We show the relationship of the various clinical and sociodemographic variables with the 2 parameters indicative of a positive methacholine test. The lower the FEF(25%-75%)/FVC ratio was, the greater the risk of HRB, after adjustment for variables (odds ratio [OR]=0.09; 95% confidence interval [CI], 0.04-0.018 for the concentration provoking a 20% decrease in FEV1, and OR=0.06; 95% CI, 0.03-0.12 for the dose provoking a 20% decrease in FEV1).

CONCLUSIONS

There is a significant association between the FEF(25%-75%)/FVC ratio and BHR after adjustment for age, atopy, smoking, geographic area, respiratory symptoms, and initial FEV1.

Determinants of maximally attained level of pulmonary function

This study investigated the determinants of sex-specific maximally attained levels of FEV(1), VC, and the ratio of FEV(1) to VC. Subjects were between the ages of 15 and 35 years (1,818 males and 1,732 females), participating in the Vlagtwedde/Vlaardingen study in The Netherlands. The subjects were followed (3-year intervals) with questionnaire, spirometry, peripheral blood eosinophil counts, and testing for airway responsiveness to histamine. Skin tests were performed only at study onset. Regression splines were used to assess the effects of these variables on levels of FEV(1), VC, and the ratio of FEV(1) to VC, with adjustment for age, height, and area of residence. Current (-44 ml/pack/day) and cumulative (-85 ml/10 packs/year) cigarette smoking were significant predictors of reduced maximal level of FEV(1) in males but not in females. The presence of respiratory symptoms (-114 ml in males, -106 ml in females), increased eosinophils (-128 ml [males], -53 ml [females]), and increased airway responsiveness (-225 ml [males], -213 ml [females]) were all significant predictors of reduced level of FEV(1). To the degree that these factors diminished plateau phase pulmonary function, they may be important predictors of chronic obstructive pulmonary disease in later life.

Cigarette smoking and dyspnea perception

Cigarette smoking has been implicated as an important risk factor for the development of respiratory symptoms in adults. The relationship of dyspnea with cigarette smoking has been examined in smokers and ex-smokers and the beneficial effects of smoking cessation have been demonstrated. Recent studies reported that in subjects who smoke cigarettes the risk of developing respiratory symptoms is higher in a dose-dependent way. Environmental tobacco smoke heavily influences the incidence of respiratory symptoms in both adults and in children. Up to the present time, the mechanisms whereby cigarette smoking causes dyspnea perception remain to be defined. Abnormalities in sensory nerves might diminish the perception of bronchoconstriction in smokers. In this regard, it has been postulated that prolonged exposure to cigarette smoke may lead to chronic depletion of sensory nerve neurotransmitters. Eosinophil airway inflammation has been proposed as a determinant of breathlessness via mechanisms affecting either the mechanical pathways that control breathlessness or the afferent nerves involved in perception of dyspnea. An increased number of eosinophils in some smokers implies the possibility that smoking may trigger immunological or other reactions associated with eosinophilia. In conclusion, cigarette smoking is by far one of the greatest risk factors for most respiratory symptoms, including dyspnea. Smoking is associated with the development of symptoms in a dose-dependent way and eosinophilia and airway hyperresponsiveness (AHR) increase the risk of developing dyspnea.

Cigarette smoke decreases pulmonary dendritic cells and impacts antiviral immune responsiveness

We investigated the impact of cigarette smoke exposure on respiratory immune defense mechanisms. Mice were exposed to two cigarettes daily, 5 d/wk, for 2-4 mo. Tobacco smoke decreased the number of dendritic cells (DCs) in the lung tissue. Furthermore, smoke exposure dramatically reduced the percentage of B7.1-expressing DCs. Because DCs are believed to be indispensable to the initiation of adaptive immune responses, we investigated the impact of cigarette smoke on immune responsiveness toward adenovirus. Mice were exposed to two cigarettes for 2-4 mo and inoculated with 2 x 10(8) pfu of a replication-deficient adenovirus on three occasions, 2 wk apart, during the last month of tobacco smoke exposure. Smoke exposure specifically prevented the expansion and maximal activation of CD4 T cells and reduced the number of both activated CD4 and CD8 T cells. Consequently, smoke exposure shifted the activated CD4:CD8 T cell ratio from 3 to 1.5 when compared with sham exposure. Significant decreases were also observed in serum adenovirus-specific pan IgG, IgG1, and IgG2a immunoglobulin levels, which was associated with diminished viral neutralization capacity. We demonstrate that chronic tobacco smoke exposure impairs the immune response against adenovirus. This may, in part, explain the increased prevalence of viral infections in chronic obstructive pulmonary disease.

Total and allergen-specific IgE levels in serum reflect blood eosinophilia and fractional exhaled nitric oxide concentrations but not pulmonary functions in allergic asthmatic children sensitized to house dust mites

Although elevated levels of serum immunoglobulin E (IgE) are considered the hallmark of atopic diseases, their clinical value in evaluating subjects with allergic disorders is under debate. To evaluate possible relationships between serum IgE levels and a variety of clinical parameters, 83 mild asthmatic children [10.98-year-old (2.95)], sensitized to house dust mites (HDM) Dermatophagoides pteronyssinus (Dp) or D. farinae (Df), were enrolled. As compared with normal control reference values detected in our laboratory, children with allergic asthma had higher blood eosinophil counts (expressed both as percentage and as absolute number) and higher fractional exhaled nitric oxide (FeNO) levels but similar values in pulmonary function parameters. In the allergic asthmatic population, serum levels of total, Dp-specific or Df-specific IgE correlated positively with eosinophil counts (Rho > or = 0.30, p < 0.01, each correlation) and FeNO levels (Rho > or = 0.33, p < 0.01, each correlation) but not with pulmonary function parameters (p > 0.1, each correlation). Finally, significant correlations, although moderate, were found in the allergic asthmatic population between eosinophil counts and FeNO levels (Rho > or = 0.42, p < 0.001, each correlation). Thus, in atopic children sensitized to HDM with mild intermittent asthma, IgE levels in blood appear to reflect systemic (blood eosinophils) and organ-specific (FeNO) markers of allergic inflammation but not pulmonary volumes or the degree of airflow limitation.

Respiratory status in dairy farmers in France; cross sectional and longitudinal analyses

AIMS

To compare respiratory status in dairy farmers with that of non-farming controls.

METHODS

Longitudinal study in the Doubs (France). From a cohort constituted in 1994 (T1), 215 (81.1%) dairy farmers and 110 (73.8%) controls were reevaluated in 1999 (T2). The protocol comprised a medical and occupational questionnaire, spirometric tests at both evaluations, allergological tests at T1, and a non-invasive measure of blood oxygen saturation (SpO2) at T2.

RESULTS

In 1999 analyses, the prevalence of chronic bronchitis was higher (p = 0.013), and FEV1/VC (p < 0.025) and SpO2 (-0.7%, p < 0.01) lower in dairy farmers than in controls. In a multiple linear regression model, farming, age, and smoking were significantly and inversely correlated with SpO2. In the whole population, the mean annual decline in FEV1 and FEV1/VC was -13.4 ml and -0.30%, respectively. Farming was associated with an accelerated decline in FEV1/VC (p < 0.025) after adjustment for covariates. No relation between allergy and respiratory function changes was observed, except for FEF25-75.

CONCLUSIONS

This prospective study shows that dairy farming is associated with an excess of chronic bronchitis, with a moderate degree of bronchial obstruction and a mild decrease in SpO2.

Reversibility to a beta2-agonist in COPD: relationship to atopy and neutrophil activation

Chronic obstructive pulmonary disease (COPD) is characterised by limited bronchial reversibility and chronic neutrophilic inflammation. However, in some cases of COPD, eosinophilic inflammation is present. We investigated the relationship between reversibility to beta2-agonist with atopy and neutrophil activation in patients with stable COPD. For this purpose, 38 outpatients with COPD (mean age: 64 years) 12 with asthma (mean age: 51 years) and 13 healthy controls (mean age: 49 years) were tested using increasing doses of inhaled salbutamol (up to 3100 microg). According to their reversibility, COPD patients were divided into two groups: reversible COPD (deltaFEV1 > or = 12% pred, n = 16) and non-reversible COPD (deltaFEV1 < 12% pred, n = 22). Atopy, assessed by skin prick, was found at similar frequencies in both COPD groups. Total serum IgE was higher in COPD patients vs. controls, but did not differ significantly between the COPD groups. The blood eosinophil count was significantly higher in the reversible COPD group than in the non-reversible COPD, and correlated with deltaFEV % pred (Rs = 0.54, P < 0.05), as well as in asthmatics. The non-reversible COPD group had a higher level of spontaneous neutrophil activation (by reduction of nitroblue tetrazolium) versus controls. We conclude that airway reversibility in COPD patients is associated with the degree of blood eosinophilia, but not with the degree of blood neutrophil activation.

Natural history of asthma

For some children, asthma is a disease whose symptoms seem to remit with time. Numerous children, however, develop disease that is persistent throughout their lifetimes and is associated with more severe symptoms, increased airway reactivity, and loss of lung function. These children typically have a family history of asthma and demonstrate increased airways reactivity and atopy in childhood. A clearer picture of the natural history of asthma in the developing child has been derived from the results of several longitudinal studies. Although some questions have been clarified, several questions still remain. Now that the incidence and severity of asthma seem to be increasing, children born in the last 10 years may experience more severe disease or a different pathophysiology than those born 30 to 40 years ago. New cohort studies are needed to assess this possibility. Additional investigations into the genetics of asthma causation will help elucidate the different phenotypic expressions of this complex disease. Once these different phenotypic groups can be identified early in life, further studies can be performed to explore the impact of therapeutic intervention on the severity of asthma symptoms and loss of lung function.

Serum interferon-gamma is associated with longitudinal decline in lung function among asthmatic patients: the Normative Aging Study

BACKGROUND

Cytokines are important mediators of the asthmatic response. A retrospective pilot study showed that serum levels of interleukin (IL)-5 and interferon (IFN)-gamma were related to lung function decline among asthmatic patients over the preceding 3 years. To confirm these findings, we tested the hypothesis that serum cytokines are associated with longitudinal lung function decline.

METHODS

We conducted a prospective, longitudinal study of 25 asthmatic and 50 nonasthmatic men (median age, 63 years; range, 45 to 80 years) participating in the Normative Aging Study. All study subjects completed two consecutive triennial examinations, including spirometry, methacholine challenge testing, allergy skin testing, and phlebotomy. Serum levels were measured for IL-4, IL-5, IL-6, IL-8, IL-10, and IFN-gamma.

RESULTS

Among asthmatic patients, a higher initial serum level of IFN-gamma was associated with a greater rate of decline of forced expiratory volume in 1 second (FEV1; beta = -67 mL/year per log increase in serum IFN-gamma, P = 0.04) and, to a lesser extent, of FEV1/forced vital capacity ratio (beta = -0.91%/year per log increase in serum IFN-gamma, P = 0.07) after adjusting for age, smoking status, and baseline level of lung function. Serum IL-5 level was associated with a rate of decline in FEV1 of borderline significance (beta = -61 mL/year per log increase in serum IL-5, P = 0.08) among asthmatic patients. These relationshipswere not observed among nonasthmatic patients.

CONCLUSIONS

Serum levels of IFN-gamma are associated with subsequent rate of change in lung function among asthmatic patients in this cohort of middle-aged and older men, and may be useful as biologic markers of risk for accelerated lung function decline in population studies.

Triggers in intrinsic asthma in the EGEA study

The objective of the study was to compare triggers for asthma attacks in a group of intrinsic (IA) and extrinsic asthmatic (EA) subjects. We included 205 asthmatic patients divided, according to skin-prick tests, in a group (n = 63) of IA and a group (n = 142) of EA. The questionnaire provided information on associated conditions (nasal polyps and intolerance to aspirin) as well as on allergenic and nonallergenic triggers. Data analysis demonstrated that in IA, some airborne nonallergenic factors were significantly more often involved. In addition, this association did hold true when comparing subgroups of patients with normal baseline FEV1 values. For those subjects, PC20 and the slopes of the dose-response curves to metacholine were comparable. In conclusion, the higher sensitivity of a group IA subjects to some nonallergenic factors is not related to a lower baseline spirometric value in this subgroup. It may be hypothesized that, in these patients, sensitivity of airways irritant receptors might be increased.

Pulmonary effects of passive smoking: the Indian experience

There are only a few studies done on pulmonary effects of passive smoking from India, which are summarized in this paper. Several vernacular tobacco products are used in India, bidis (beedis) being the commonest form of these. Bidis contain a higher concentration of nicotine and other tobacco alkaloids compared to the standard cigarettes (e.g., the sum of total nicotine and minor tobacco alkaloids was 37.5 mg in bidi compared to 14–16 mg in Indian or American cigarettes in one study). A large study performed on 9090 adolescent school children demonstrated environmental tobacco smoke (ETS) exposure to be associated with an increased risk of asthma. The odds ratio for being asthmatic in ETS-exposed as compared to ETS-unexposed children was 1.78 (95% CI: 1.33–2.31). Nearly one third of the children in this study reported non-specific respiratory symptoms and the ETS exposure was found to be positively associated with the prevalence of each symptom. Passive smoking was also shown to increase morbidity and to worsen the control of asthma among adults. Another study demonstrated exposure to ETS was a significant trigger for acute exacerbation of asthma. Increased bronchial hyper-responsiveness was also demonstrated among the healthy nonsmoking adult women exposed to ETS. Passive smoking leads to subtle changes in airflow mechanics. In a study among 50 healthy nonsmoking women passively exposed to tobacco smoke and matched for age with 50 unexposed women, forced expiratory volume in first second (FEV1) and peak expiratory flow (PEF) were marginally lower among the passive smokers (mean difference 0.13 L and 0.20 L-1, respectively), but maximal mid expiratory flow (FEF25–75%), airway resistance (Raw) and specific conductance (sGaw) were significantly impaired. An association between passive smoking and lung cancer has also been described. In a study conducted in association with the International Agency for Research on Cancer, the exposure to ETS during childhood was strongly associated with an enhanced incidence of lung cancer (OR = 3.9, 95% CI 1.9–8.2). In conclusions several adverse pulmonary effects of passive smoking, similar to those described from the western and developed countries, have been described from India.

Airway reactivity response to aged carbon-graphite/epoxy composite material smoke

Exposure of naïve guinea pigs for a total of 30 min to aged smoke from pyrolysis of 5, 10 and 100 g of carbon-graphite/epoxy-advanced composite material (cgeCM) elicited changes in the ventilation and breathing pattern reminiscent of an acute, asthmatic episode. The severity of these responses was dose related. Although breathing pattern changes were not definitive of stimulation by a single type of respiratory irritant, non-dimensional indices derived from breath structure appeared to be characteristic of bronchoconstriction possibly complicated by CO(2)-stimulated ventilation. The highest exposure concentration also elicited convulsions in the animals, which may or may not be related to the airway reactivity (AR) response. Upon treatment with fresh air, breathing returned to normal. However, this recovery was transient with some respiratory parameters returning to abnormal levels, possibly indicating a rebound or delayed component of the response. Filtration of particulate material from the smoke moderated but did not eliminate the AR response. Animals exposed to diluted smoke from the pyrolysis of 2 g of cgeCM showed no remarkable changes in breathing or ventilation, suggesting that there may be a threshold for aged cgeCM smoke-elicited AR response.

Body mass index and asthma in adults in families of subjects with asthma in Anqing, China

We conducted a cross-sectional study of 7,109 adults from families of subjects with asthma in the province of Anhui, China. Asthma was defined either as a combination of physician-diagnosed asthma, airway responsiveness to methacholine at < or = 25 mg/ml and two or more respiratory symptoms or asthma attacks ("asthma"); or as a combination of airway responsiveness to methacholine at < or = 8 mg/ml and two or more respiratory symptoms or asthma attacks ("symptomatic airway hyperresponsiveness [AHR]"). After adjusting for intensity of cigarette smoking and other variables, both extremes of the body mass index (BMI) distribution were associated with symptomatic AHR in men and women (p < 0.01). In the multivariate analysis, both under- and overweight were associated with asthma in women, and underweight was associated with asthma in men. Among men, those with BMIs of 16 and 30 kg/m(2) had 2.5 and 2.3 times higher odds of symptomatic AHR, respectively, than those whose BMI was 21 kg/m(2) (95% CI for OR(16 vs. 21 kg/m)(2) = 1.4 to 3.8; 95% CI for OR(30) (vs.) (21) (kg/m)(2) = 1.2 to 5.0). Among women, those with BMIs of 16 and 30 kg/m(2) had 2.0 and 2.3 times higher odds of symptomatic AHR than those whose BMI was 21 kg/m(2) (95% CI for OR(16) (vs.) (21) (kg/m)(2) = 1.3 to 3.1; 95% CI(30) (vs.) (21) (kg/m)(2) = 1.2 to 4.5). Among adults in families of subjects with asthma living in rural China, both underweight and overweight are associated with an increased risk of asthma.

Impulse oscillometry in healthy nonsmokers and asymptomatic smokers: effects of bronchial challenge with methacholine

The clinical application of respiratory impedance measurements by oscillation techniques for monitoring bronchial challenge testing is hampered by the fact that data in healthy nonsmokers and asymptomatic smokers are very limited. The objective of this study was to analyze the changes in impedance to a methacholine provocation test in healthy nonsmokers and asymptomatic smokers, and to investigate whether smokers show a different response compared to nonsmokers. The response to methacholine challenge was assessed by impulse oscillometry (IOS) (resistance R and reactance X at 5, 10, 15, 20, 25, and 35 Hz) and spirometry (FEV1, MEF50) in 105 healthy subjects (55 nonsmokers: "NS"; 50 asymptomatic smokers: "S") in whom the provocation dose of 2.44 mg methacholine did not result in a fall of FEV1 below 20% predicted of the baseline value. The baseline reactance X values of S were significantly lower compared to NS from 10 to 35 Hz (p < or = 0.01), whereas S and NS did not differ in resistance R over the whole frequency spectrum from 5 to 35 Hz. S showed a significantly higher mean baseline resonant frequency X(f0); i.e., the frequency at which inertial forces are equal and opposite to elastic forces, compared to NS (NS: X(fo) = 10.8+/-2.9 Hz; S = 12.6+/-4.0 Hz, p = 0.01). In both groups methacholine challenge resulted in an increase in R (f) especially at 5 and 10 Hz, and a marked decrease in X(f) over the whole frequency spectrum. In S a significantly higher decrease of postchallenge X5Hz and X10Hz was measured compared to NS (NS: deltaX(5Hz) = -0.044+/-0.003; S: deltaX(5HZ) = -0.083+/-0.013; p = 0.0017. NS: deltaX(10Hz) = -0.050+/-0.001; S: deltaX(10Hz) = -0.082+/-0.017; p = 0.008). R and X at low frequencies showed a three to four times higher postchallenge reaction compared to FEV1. Pre- and postchallenge FEV1 did not correlate with resistance R (f) and reactance X(f) over the whole frequency spectrum. In S perchallenge X(f) values from 10 to 35 HZ were significantly lower, and postchallenge decrease of X5Hz and X10Hz values were significantly higher compared to that of NS, whereas pre- and postchallenge R(f) values were similar in both groups. These results can be explained by changes in the elastic properties of the lung induced by a diffuse subclinical respiratory bronchiolitis.

Prevalence of bronchial hyperresponsiveness among HIV-infected men

HIV infection is associated with immune dysregulation primarily affecting T-cell function, whereas asthma is related to excessive T-cell activity. We compared the prevalence of asthma and related conditions among adult seropositive men with the prevalence among men of similar age drawn from the general population. Seropositive men had a significantly more frequent occurrence of wheezing (54.4 versus 21.2%), bronchial hyperresponsiveness (BHR) to methacholine (26.2 versus 14.4%), and an elevated total serum IgE (37.8 versus 25.7%). Differences in BHR were significant only among smokers. Among the seropositive men, FEV(1)/FVC and an elevated IgE were the principal determinants of BHR. Our results suggest that the frequency of asthma may be underestimated in HIV disease. Furthermore, the frequent occurrence of BHR in HIV-infected men who smoke (30.1%) suggests this group may be especially susceptible to the adverse effects of cigarette smoke.

Association of airway responsiveness with asthma and persistent wheeze in a Chinese population

STUDY OBJECTIVES

Data from a cross-sectional study were analyzed to examine the association of increased airway responsiveness with physician-diagnosed asthma and persistent wheeze.

DESIGN

Two methods for calculating the provocative dose that decreases the airflow rate by 20% (PD(20)) were used as indexes for increased airway responsiveness: (1) a 20% drop in FEV(1) calculated from baseline FEV(1) (PD(20)b), and (2) a 20% drop in FEV(1) from FEV(1) measurements after inhalation of saline solution (PD(20)s). Both PD(20)b and PD(20)s were measured through induction by varying doses of methacholine.

SETTING

Anqing, Anhui Province, China.

PARTICIPANTS

Study subjects were 8 to 74 years of age and were classified into four groups: children (< 15 years old), young adults (15 to 29 years old), adults (30 to 44 years old), and older adults (> or 5 years old).

INTERVENTIONS

The differences in estimated odds ratios of airway hyperresponsiveness with asthma and wheeze, sensitivity and specificity, and coefficients of variation were compared between PD(20)b and PD(20)s. The sample for analysis consisted of 10,284 subjects from 2,663 nuclear families with complete data on wheeze, asthma, and major potential confounding factors.

MEASUREMENTS AND RESULTS

The prevalence of asthma in this sample was lowest in subjects with no demonstrable PD(20) and had a reverse dose-response relationship with PD(20) across all age groups. Using the receiver operating characteristic, the sensitivity and specificity of the PD(20)s or PD(20)b were found to be almost identical. A similar trend was found for persistent wheeze, although the estimated odds ratios for persistent wheeze appeared slightly smaller than those for physician-diagnosed asthma.

CONCLUSIONS

This study demonstrates a dose-response relationship between increased airway responsiveness and asthma and wheeze in this Chinese population. PD(20)s or PD(20)b yielded virtually indistinguishable results, which indicated that either of the two tests could serve as an index of airway hyperresponsiveness.

Evolving concepts in the pathogenesis of chronic obstructive pulmonary disease

It is arguable that more biologic insight has been gained from the study of COPD than from any other pulmonary disorder. A vast knowledge of the biology of extracellular matrix proteins, proteinases, and proteinase inhibitors has largely stemmed from the elastase:anti-elastase hypothesis for the pathogenesis of emphysema. An equally compelling case could be made that interest in, and funding for, COPD research has been woeful, and investigators have made no significant medical breakthroughs in the treatment of this disorder, which, unfortunately, is becoming epidemic worldwide. Indeed, it cannot be argued that physicians have very little treatment to offer to the many patients with COPD. Humankind is rapidly approaching a time when all human genes will be sequenced, and genetic engineering will allow determination of the function of these proteins in vivo. Expression profiling and bioinformatics will allow clinicians to assess the spectrum of genes and proteins regulated in biologic processes, no longer limiting study to naïve candidate genes. These advances will allow investigators to decipher precise pathways of complex diseases, identify genetic and environmental interactions, and ultimately lead to specific (pre)diagnoses and rational treatment. Answers to the question as to why only a subset of smokers develop COPD will enhance the understanding of the disease process. Fortunately, there has been a resurgence of interest in COPD, led largely by the pharmaceutical industry, which has discovered the potential of this unmet need. Consequently, these state-of-the-art scientific techniques are being directly applied to COPD, lending hope for the future. Of even greater importance, the tide seems to be turning on the cigarette industry. Although difficult to imagine, perhaps cigarettes will disappear in this lifetime or at least the next generation won't be fooled by this deadly habit! Well ... the rational therapy thing could work.

Application of an algorithm for the diagnosis of asthma in Chinese families: limitations and alternatives for the phenotypic assessment of asthma in family-based genetic studies

Phenotype assessment is a crucial issue in gene mapping studies of asthma. Recently, Panhuysen and coworkers proposed an algorithm to define the asthma phenotype in gene mapping family-based studies. We classified members of 2,756 Chinese families ascertained on the basis of the presence of two or more siblings and no more than one parent with asthma using a slightly modified version of the aforementioned algorithm. Among 4,097 Chinese parents, 404 (9.9%) were classified as having "definite asthma," 284 (6.9%) as "probable asthma," 1,193 (29.1%) as "unclassifiable obstructive airway disease, " 626 (15.3%) as "COPD," and 1,590 (38.8%) as "unaffected" (no obstructive airway disease). Among 6,424 Chinese offspring, 1,065 (16.6%) were classified as having "definite asthma," 820 (12.8%) as "probable asthma," 1,996 (31.1%) as "unclassifiable obstructive airway disease," 228 (3.5%) as "COPD," and 2,315 (36%) as "unaffected." The use of the algorithm proposed by Panhuysen and coworkers in a Chinese population with a high prevalence of smoking would result in the exclusion of subjects with asthma who smoke or who have severe airflow obstruction from linkage analysis, as well as in an inability to explore any potential interactions between genetic factors and cigarette smoking in the pathogenesis of asthma. In the absence of a "gold standard," definitions of asthma that incorporate a combination of respiratory symptoms, increased airway responsiveness or bronchodilator response, and a physician's diagnosis of asthma are reasonable. The choice of a particular diagnostic algorithm for family-based genetic studies of asthma should be made according to factors such as the prevalence of smoking in the study population. Genetic studies of intermediate phenotypes related to asthma, which are objectively defined and may be influenced by a smaller number of genes, continue to be of great importance.

Histamine airway hyper-responsiveness and mortality from chronic obstructive pulmonary disease: a cohort study

BACKGROUND

Smoking and airway lability, which is expressed by histamine airway hyper-responsiveness, are known risk factors for development of respiratory symptoms. Smoking is also associated with increased mortality risks. We studied whether airway hyper-responsiveness is associated with increased mortality, and whether this risk was independent of smoking and reduced lung function.

METHODS

We followed up 2008 inhabitants of the communities of Vlagtwedde, Vlaardingen, and Meppel (Netherlands), who had histamine challenge test data, from 1964-72 for 30 years. Follow-up was 99% successful (29 patients lost to follow-up) with 1453 participants alive and 526 deaths (246 died from cardiovascular disease, 54 from lung cancer, and 21 from chronic obstructive pulmonary disease [COPD]).

FINDINGS

Mortality from COPD increased with more severe hyper-responsiveness; relative risks of 3.83 (95% CI 0.97-15.1), 4.40 (1.16-16.7), 4.78 (1.27-18.0), 6.69 (1.71-26.1), and 15.8 (3.72-67.1) were associated with histamine thresholds of 32 g/L, 16 g/L, 8 g/L, 4 g/L, and 1 g/L, respectively, compared with no hyper-responsiveness. These risks were adjusted for sex, age, smoking, lung function, body-mass index, positive skin tests, eosinophilia, asthma, and city of residence.

INTERPRETATION

Increased histamine airway hyper-responsiveness predicts mortality from COPD. Although this trend was more pronounced in smokers, an increasing proportion of COPD deaths with increasing hyper-responsiveness was also present among individuals who had never smoked.

Withdrawal of chronic systemic corticosteroids in patients with COPD: a randomized trial

The benefits of chronic systemic corticosteroids for patients with chronic obstructive pulmonary disease (COPD) are not well established. To determine whether chronic corticosteroid treatment can be safely withdrawn in "steroid-dependent""COPD patients, we performed a double-blind, placebo-controlled study of 38 patients with steroid-dependent COPD. Patients were randomly assigned to receive their usual maintenance prednisone dose for 6 mo (continuous group) or to be withdrawn from prednisone at a rate of 5 mg per week (demand group). The number of COPD exacerbations per patient (primary outcome) was 2.5 +/- 2.7 (mean +/- SD) in the continuous group and 2.7 +/- 2.5 in the demand group (p = 0.60, 95% confidence interval for the difference: -1.1 to 1.7). Spirometric results, dyspnea, and health-related quality of life did not differ significantly in the two groups. The average daily corticosteroid dose was 10.7 +/- 5.2 mg in the continuous group and 6.3 +/- 6.4 mg in the demand group (p = 0.003). Weight decreased in the demand group by 4.8 +/- 2.0 kg, compared with an increase in the continuous group of 0.5 +/- 3.5 kg (p = 0.007). Discontinuation of chronic systemic corticosteroid treatment in steroid-dependent COPD patients did not cause a significant increase in COPD exacerbations, but did reduce total systemic corticosteroid use and body weight. Larger studies may be warranted to establish the relative risks and benefits of chronic corticosteroid treatment of patients with COPD.

Office spirometry for lung health assessment in adults: A consensus statement from the National Lung Health Education Program

COPD is easily detected in its preclinical phase using spirometry, and successful smoking cessation (a cost-effective intervention) prevents further disease progression. This consensus statement recommends the widespread use of office spirometry by primary-care providers for patients >/= 45 years old who smoke cigarettes. Discussion of the spirometry results with current smokers should be accompanied by strong advice to quit smoking and referral to local smoking cessation resources. Spirometry also is recommended for patients with respiratory symptoms such as chronic cough, episodic wheezing, and exertional dyspnea in order to detect airways obstruction due to asthma or COPD. Although diagnostic-quality spirometry may be used to detect COPD, we recommend the development, validation, and implementation of a new type of spirometry-office spirometry-for this purpose in the primary-care setting. In order to encourage the widespread use of office spirometers, their specifications differ somewhat from those for diagnostic spirometers, allowing lower instrument cost, smaller size, less effort to perform the test, improved ease of calibration checks, and an improved quality-assurance program.

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.

An approach to the diagnosis of occupational asthma

BACKGROUND

Occupational Asthma (OA) is a common disorder attributable to causes and conditions found in the workplace. Occupational asthma may have an immunologic or nonimmunologic basis and may be caused by several hundred agents. A number of factors may increase the risk of developing OA including genetic, industrial, meteorologic, social, and medical factors.

METHODS

The diagnosis is best made by fulfilling well-defined clinical criteria by way of a meticulous and oftentimes arduous evaluation. Pre-existing asthma and allergy, along with other special variants of asthma and unrelated pulmonary disorders which can masquerade as asthma, must be ruled out.

CONCLUSION

Convincing physiologic evidence that demonstrates a cause-and-effect relationship must be obtained before a definitive diagnosis of work-related asthma is made.

A randomized controlled trial on the effect of inhaled corticosteroids on airways inflammation in adult cigarette smokers

STUDY OBJECTIVE

To determine whether inhaled corticosteroid treatment can reduce airways inflammation in adult cigarette smokers.

DESIGN

This was a randomized, placebo-controlled, double-blinded clinical trial.

SETTING

The subjects were recruited from the community by advertising.

PARTICIPANTS

Seventy-one adults with a > or = 5 pack-year history who were current smokers, had a normal FEV1, and produced sputum daily.

INTERVENTION

Sixty subjects were randomized to receive four puffs of placebo or beclomethasone dipropionate ([BDP]; total dosage, 1,000 microg/d) using a metered-dose aerosol inhaler with a valved holding chamber (AeroChamber; Trudell Medical; London, Ontario, Canada) for 28 days.

MEASUREMENTS AND RESULTS

Eleven subjects were not randomized because of poor compliance. The primary outcome was fractional airway neutrophilia, as assessed by a differential cell count of sputum. Additional outcome measures were spirometry, measurement of airway responsiveness by methacholine challenge, and lung epithelial permeability measured by the clearance of radiolabeled diethylenetriamine pentaacetic acid. There were no significant differences between the two groups in any outcome measurement after 4 weeks of treatment.

CONCLUSIONS

With normal spirometry, we found no benefit of treatment with inhaled BDP, 1,000 microg/d, on noninvasive measures of airways inflammation in adult smokers. This indicates that cigarette smoke-induced inflammation in its early stages (before a demonstrable airflow obstruction) is not steroid sensitive. This may occur because the site of involvement is not accessible to inhaled medications or because the inflammatory process is resistant to moderate doses of inhaled corticosteroids.

The natural history of asthma in adults: the problem of irreversibility

Asthma is common, affecting 5% to 10% of adults; asthma is progressive, leading to irreversible obstruction in 80% of elderly patients; and asthma is complex, often complicated by coexisting lung diseases. This loss of lung function results from 4 independent pathologic conditions: (1) airway remodeling, especially in the small airways, from the lymphocytic-eosinophilic inflammation that characterizes asthma; (2) bronchiectasis; (3) postinfectious pulmonary fibrosis; and (4) emphysema and chronic bronchitis from tobacco smoke. Deterioration in lung function develops faster in nonallergic patients with intrinsic asthma during the period shortly after onset of asthma and in older patients. About 4% of patients die of asthma, and most are elderly. Death most often results from complications of irreversible obstruction or cardiotoxicity of bronchodilator therapy. More research is needed to improve therapy for preventing remodeling of small airways, to confirm the frequency of bronchiectasis and postinfectious fibrosis and to determine their causes, and to develop diagnostic criteria to identify these complications. Meanwhile, clinicians treating adult asthmatic patients need to be aggressive in preventing the damage from cigarette smoke; in immunizing for influenza and pneumococcus infection and identifying and treating respiratory infections, particularly at times of acute exacerbations; in diagnosing and managing bronchiectasis; and in objectively confirming the efficacy of asthma therapy to prevent illness from overtreatment with glucocorticoids and bronchodilators.

Thorax high resolution computerized tomography findings in asthmatic children with unusual clinical manifestations

BACKGROUND

It has been consistently observed in high resolution computerized tomography (HRCT) scans that asthmatic patients manifest more abnormalities related to airways remodeling than do normal subjects.

OBJECTIVE

To find the underlying abnormalities in the lungs of asthmatic children with unusual manifestations.

METHOD

Asthmatic children not responding as expected to inhaled steroid therapy with or without localized permanent or temporary recurrent auscultation findings (rales) were evaluated with chest radiographs and HRCT scans. Bronchoscopy was performed on the ones with localized rales.

RESULTS

The sample consisted of 16 asthmatic children (6 girls and 10 boys, mean age = 7.75+/-4.43 years). Chest radiograph abnormality rate was 44% and the thorax HRCT scan abnormality rate was 75% (56% fibrotic retractions, 38% atelectasis, 19% bronchiectasis, and 19% bronchial wall thickening). Two patients with localized permanent rales and with right middle lobe (RML) atelectasis in HRCT scan underwent bronchoscopy which revealed RML syndrome due to mucus plugging in one and lymph node pressure in the other. In one patient with localized temporary recurrent rales and major bronchiectasis in HRCT scan, bronchoscopy revealed bronchitis. The patient with RML syndrome due to mucus plugging required lobectomy.

CONCLUSION

We conclude with this experience that thorax HRCT scanning may be a helpful adjunct in the evaluation of an asthmatic children with atypical clinical findings.

The relationship of skin test positivity, high serum total IgE levels, and peripheral blood eosinophilia to symptomatic and asymptomatic airway hyperresponsiveness

The relationships of skin test positivity, high serum total IgE levels (> 100 kU/L), and peripheral blood eosinophilia (>/= 275 cells/microliter) to symptomatic (either chronic cough, chronic phlegm, bronchitis episodes, dyspnea, wheeze, or asthma) and asymptomatic bronchial hyperresponsiveness (BHR) were studied cross-sectionally in 620 adult subjects who participated in the Vlagtwedde-Vlaardingen Study of 1989 and 1990. Eosinophilia (OR = 2.06, 95% CI = 1.28 to 3.31) and skin test positivity (OR = 1.66, 95% CI = 1.02 to 2.71) were both significantly associated with BHR independent of age, sex, smoking, and urban area of residence. High serum total IgE levels were not associated with BHR (OR = 1.29, 95% CI = 0.81 to 2.03). Separate analyses for symptomatic and asymptomatic subjects showed that the higher risk of BHR with skin test positivity applied only to symptomatic subjects (OR = 5.78, 95% CI = 1.63 to 20.51), independent of eosinophilia and high serum total IgE levels. The higher risk of BHR with eosinophilia was not different between symptomatic and asymptomatic subjects, and independent of skin test positivity and high serum total IgE levels. The results of this study show that, in the general adult population, eosinophilia is associated with BHR both in symptomatic and asymptomatic persons, whereas skin test positivity is associated with BHR only in symptomatic subjects.