Bronchial reactivity to inhaled histamine and annual rate of decline in FEV1 in male smokers and ex-smokers

Anti-Interleukin-5 Therapy Is Associated with Attenuated Lung Function Decline in Severe Eosinophilic Asthma Patients from the Belgian Severe Asthma Registry

BACKGROUND

Asthmatics have accelerated lung function decline over time compared with healthy individuals.

OBJECTIVE

To evaluate risk factors for accelerated lung function decline.

METHODS

In a longitudinal analysis on severe asthmatics enrolled in the Belgian Severe Asthma Registry with at least 2 visits a minimum of 12 months apart, we compared characteristics of patients with and without decline (loss of post-bronchodilation forced expiratory volume in 1 s [FEV₁] (% predicted)/y greater than zero) over time. Multiple linear regression was applied to study the factors independently associated with FEV₁ decline.

RESULTS

In the overall population (n = 318), median annual FEV₁ decline was 0.27 (-4.22 to 3.80) % predicted/y over a period of 23 months (12-41 months). Asthma was less controlled at baseline in nondecliners than in decliners (53%). Lung function and residual volume at baseline were higher in the declining group. Decliners presented with increased bronchial reactivity (ie, a lower provocative concentration of methacholine causing a 20% fall in FEV₁) at baseline. Twenty-five percent of nondecliners were started on anti-interleukin-5 (anti-IL-5) for severe eosinophilic asthma during the study compared with 10% of decliners. The multivariable model suggested that Asthma Control Questionnaire score at baseline, late-onset asthma, and addition of anti-IL-5 during follow-up were associated with lower FEV₁ decline, independently from other variables such as evolution in exacerbations, smoking status, inhaled corticosteroids or oral corticosteroids dose, or add-on anti-immunoglobulin E over time, whereas reversibility to salbutamol and higher FEV₁ were associated with accelerated FEV₁ decline.

CONCLUSIONS

Add-on therapy with anti-IL-5 in severe eosinophilic asthma was associated with an attenuated FEV₁ decline. The causality of this observation should, however, be confirmed in future prospective controlled studies.

Blood eosinophils, FeNO and small airways dysfunction in predicting airway hyperresponsiveness in patients with asthma-like symptoms

PURPOSE

In patients with suspected asthma and no airflow limitation in spirometry, methacholine challenge testing (MCT) for airway hyperresponsiveness (AHR) is an option of documenting variable airflow limitation. The goal of the study was to assess the ability of blood eosinophils, fractional concentration of exhaled nitric oxide (FeNO) and distal airways function to discriminate patients with AHR from those with normal airway responsiveness (AR).

METHODS

We analyzed baseline data from 42 participants who underwent MCT because of asthma-like symptoms and no airflow limitation in spirometry.

RESULTS

Eosinophil count was higher among participants with borderline AHR comparing to those with normal AR (340 cells/µL, IQR 285-995 vs. 125 cells/µL, IQR 75-180, post-hoc p = 0.041). FeNO and percent predicted of functional residual volume (FRC%pred) were higher in participants with moderate-marked AHR compared to those with normal AR (40 ppb, IQR 30.5-100.5 vs. 18 ppb, IQR 13-50, post-hoc p = 0.008; 140.1%±17.0% vs. 107.3%±20.7%, post-hoc p < 0.001, respectively). Percentage predicted of the maximal expiratory flow at 25% of the forced vital capacity (MEF₂₅%pred) was lower in participants with mild AHR and borderline AHR compared to those with normal AR (72.9%±16.9% vs. 113.0%±36.8%, post-hoc p = 0.017; 73.3%±15.9% vs. 113.0%±36.8%, post-hoc p = 0.045; respectively). Level of AHR correlated with eosinophil count, FeNO, MEF₂₅%pred, forced expiratory flow between 25% and 75% of vital capacity (FEF_25-75%pred), FRC%pred and specific airway resistance (sR_aw).

CONCLUSIONS

Blood eosinophils, FeNO and small airways dysfunction markers are related to the level of AR to methacholine in patients with asthma-like symptoms and no airflow limitation in spirometry.

Increase in blood eosinophils during follow-up is associated with lung function decline in adult asthma

BACKGROUND

Asthma is associated with accelerated rate of lung function (FEV₁) decline.

OBJECTIVE

To determine predictive factors associated with FEV₁ decline in adult asthma.

METHODS

A retrospective study was conducted in 229 asthmatics recruited from the University Asthma Clinic of Liege. Subjects had at least two visits with post-bronchodilation (post-BD) FEV₁ and minimum one year between them. A multivariable linear regression analysis was conducted in order to come up with factors associated with lung function decline.

RESULTS

Post-BD FEV₁ decline in % predicted. y^-1 was 0.2 (95%CI -2.0 to 2.8) in the overall population. Our population was made up of mild to moderate asthmatics [1] for 58%, aged 50 (41-60) years old, 62% were female and 59% were atopic. Median ICS dose was 1000 μg beclomethasone equivalent (CFC)/day with 81% treated at baseline. Time between visits was 46.8 ± 32.1 months. The univariate linear regression analysis revealed a negative association between % predicted FEV₁ decline and baseline ACQ (p < 0.0001) and blood eosinophils (% and/mm³) (p < 0.0001 and p < 0.0001). A positive association was found between % predicted FEV₁ decline and baseline pre-BD FEV1 (mL) values (p = 0.001), blood neutrophils (%) (p = 0.02), change in blood eosinophils (%) (p < 0.0001), time between visits (months) (p < 0.0001). The predictive variables for accelerated decline highlighted by the multivariable analysis (r² = 0.39) were change in blood eosinophils (%) over time (p = 0.002) and time between visits (months) (p < 0.0001).

CONCLUSION

These findings highlight a new value for blood eosinophil counts as their increase over time predicts greater lung function decline in asthma.

Associations between blood eosinophils and decline in lung function among adults with and without asthma

Eosinophilic inflammation and airway remodelling are characteristic features of asthma, but the association between them is unclear. We assessed associations between blood eosinophils and lung function decline in a population-based cohort of young adults.We used linear mixed models to analyse associations between blood eosinophils and spirometry at 21, 26, 32 and 38 years adjusting for sex, smoking, asthma and spirometry at age 18 years. We further analysed associations between mean eosinophil counts and changes in spirometry from ages 21 to 38 years.Higher eosinophils were associated with lower forced expiratory volume in 1 s (FEV₁)/forced vital capacity (FVC) ratios and lower FEV₁ % predicted values for both pre- and post-bronchodilator spirometry (all p-values ≤0.048). Although eosinophil counts were higher in participants with asthma, the associations between eosinophils and spirometry were similar among participants without asthma or wheeze. Participants with mean eosinophil counts >0.4×10⁹ cells·L^-1 between 21 and 38 years had greater declines in FEV₁/FVC ratios (difference 1.8%, 95% CI 0.7-2.9%; p=0.001) and FEV₁ values (difference 3.4% pred, 95% CI 1.5-5.4% pred); p=0.001) than those with lower counts.Blood eosinophils are associated with airflow obstruction and enhanced decline in lung function, independently of asthma and smoking. Eosinophilia is a risk factor for airflow obstruction even in those without symptoms.

Allergic bronchopulmonary aspergillosis in a patient with chronic obstructive pulmonary disease

Allergic bronchopulmonary aspergillosis (ABPA) is a debilitating lung disease which occurs as a result of interplay between a variety of host and environmental factors. It occurs in certain susceptible individuals who develop hypersensensitivity to the colonised Aspergillus species. ABPA is a complicating factor in 2% of patients with asthma and is also seen in patients with cystic fibrosis. Asthma and chronic obstructive pulmonary disease (COPD) are known to share key elements of pathogenesis. It is well known that ABPA can occur in patients with asthma, but it has recently been reported in patients with COPD as well. We report a 55-year-old male ex-smoker who presented with complaints of exertional breathlessness and productive cough for five years and an episode of haemoptysis four days prior to presentation. Spirometery showed airflow obstruction which was not reversible with bronchodilators. Chest CT scan revealed paraseptal emphysema along with central bronchiectasis (CB) in the right upper lobe and bilateral lower lobes. A type I skin hypersensitivity reaction to Aspergillus species was elicited. He fulfilled the serological criteria for ABPA and was diagnosed as having concomitant COPD and ABPA-CB. The patient was initiated on therapy for COPD along with oral corticosteroids, on which he had remarkable symptomatic improvement.

Systematic review of the evidence relating FEV1 decline to giving up smoking

BACKGROUND

The rate of forced expiratory volume in 1 second (FEV1) decline ("beta") is a marker of chronic obstructive pulmonary disease risk. The reduction in beta after quitting smoking is an upper limit for the reduction achievable from switching to novel nicotine delivery products. We review available evidence to estimate this reduction and quantify the relationship of smoking to beta.

METHODS

Studies were identified, in healthy individuals or patients with respiratory disease, that provided data on beta over at least 2 years of follow-up, separately for those who gave up smoking and other smoking groups. Publications to June 2010 were considered. Independent beta estimates were derived for four main smoking groups: never smokers, ex-smokers (before baseline), quitters (during follow-up) and continuing smokers. Unweighted and inverse variance-weighted regression analyses compared betas in the smoking groups, and in continuing smokers by amount smoked, and estimated whether beta or beta differences between smoking groups varied by age, sex and other factors.

RESULTS

Forty-seven studies had relevant data, 28 for both sexes and 19 for males. Sixteen studies started before 1970. Mean follow-up was 11 years. On the basis of weighted analysis of 303 betas for the four smoking groups, never smokers had a beta 10.8 mL/yr (95% confidence interval (CI), 8.9 to 12.8) less than continuing smokers. Betas for ex-smokers were 12.4 mL/yr (95% CI, 10.1 to 14.7) less than for continuing smokers, and for quitters, 8.5 mL/yr (95% CI, 5.6 to 11.4) less. These betas were similar to that for never smokers. In continuing smokers, beta increased 0.33 mL/yr per cigarette/day. Beta differences between continuing smokers and those who gave up were greater in patients with respiratory disease or with reduced baseline lung function, but were not clearly related to age or sex.

CONCLUSION

The available data have numerous limitations, but clearly show that continuing smokers have a beta that is dose-related and over 10 mL/yr greater than in never smokers, ex-smokers or quitters. The greater decline in those with respiratory disease or reduced lung function is consistent with some smokers having a more rapid rate of FEV1 decline. These results help in designing studies comparing continuing smokers of conventional cigarettes and switchers to novel products.

Small airway pathology and bronchoreversibility in advanced emphysema

BACKGROUND

Poorly reversible airflow obstruction is a hallmark feature of chronic obstructive pulmonary disease (COPD). However, some COPD patients demonstrate significant bronchodilator reversibility (BDR). The pathologic features associated with the presence or absence of this phenomenon are not known.

METHODS

We analyzed 67 patients with advanced upper lobe predominant emphysema who underwent lung volume reduction surgery and divided them into 2 groups: the reversible group [BD(+)] had a >12% and >200 mL increase in FEV(1) or FVC with bronchodilator; the irreversible group [BD(-)] had a <or=12% and <or=20 mL increase in FEV(1) and FVC. We measured the epithelial height (EH) and areas of epithelium (EA), subepithelium (SEA), smooth muscle (SMWA), and total wall (TWA) of the small airways (<2 mm in internal diameter) in the resected specimens, and adjusted these measurements for basement membrane area (BMA) or perimeter (BMP).

RESULTS

Despite similar baseline characteristics, the BD(+) group had a smaller EH (0.036 mm vs. 0.042 mm, p = 0.005) and EH/BMP (0.012 vs. 0.014, p = 0.007), and a greater SMWA/BMA (0.491 vs. 0.430, p = 0.034) compared to the BD(-) group. In addition, EA trended to be smaller in the BD(+) group when compared to the BD(-) group (0.160 mm(2) vs. 0.184 mm(2), p = 0.06). In a subset of patients with consistent patterns of BDR on serial testing, the BD(+) group had greater SMWA/BMA (0.518 vs. 0.433, p = 0.049) and TWA/BMA (1.405 vs. 1.266, p = 0.036) compared to the BD(-) group.

CONCLUSIONS

Small airway smooth muscle mass may play a role in determining BDR in severe emphysema.

Inhaled corticosteroids in chronic obstructive pulmonary disease: a review

IMPORTANCE OF THE FIELD

Chronic obstructive pulmonary disease (COPD) is a disease characterized by chronic airflow obstruction and a progressive lung function decline. Although widely used, the efficacy of inhaled corticosteroids (ICS) in the treatment of COPD remains a matter of debate.

AREAS COVERED IN THIS REVIEW

This article reviews the evidence about the effects of inhaled corticosteroids in the treatment of COPD.

WHAT THE READER WILL GAIN

Short-term treatment with ICS improves lung function and quality of life; in addition, several studies with longer follow-up have shown less decline over time in quality of life, and fewer exacerbations. By contrast, long-term studies have been unable to show substantial improvement in the decline of lung function in COPD. Based on these findings, it was concluded that the use of ICS did not influence the natural course of COPD. However, this conclusion has been challenged by two subsequent studies, TORCH and GLUCOLD, which both showed a reduction in lung-function decline over time with the use of ICS. These two studies indicate that ICS might indeed influence the natural course of the disease, at least in a subgroup of COPD patients.

TAKE HOME MESSAGE

Further studies are needed to identify which individuals have a favorable short- and long-term response to ICS treatment.

Physical activity and bronchial hyperresponsiveness: European Community Respiratory Health Survey II

BACKGROUND

Identification of the risk factors for bronchial hyperresponsiveness (BHR) would increase the understanding of the causes of asthma. The relationship between physical activity and BHR in men and women aged 28.0-56.5 years randomly selected from 24 centres in 11 countries participating in the European Community Respiratory Health Survey II was investigated.

METHODS

5158 subjects answered questionnaires about physical activity and performed BHR tests. Participants were asked about the frequency and duration of usual weekly exercise resulting in breathlessness or sweating. BHR was defined as a decrease in forced expiratory volume in 1 s of at least 20% of its post-saline value for a maximum methacholine dose of 2 mg.

RESULTS

Both frequency and duration of physical activity were inversely related to BHR. The prevalence of BHR in subjects exercising or=4 times a week was 14.5%, 11.6% and 10.9%, respectively (p<0.001). The corresponding odds ratios were 1.00, 0.78 (95% CI 0.62 to 0.99) and 0.69 (95% CI 0.50 to 0.94) after controlling for potential confounding factors. The frequency of BHR in subjects exercising <1 h, 1-3 h and >or=4 h a week was 15.9%, 10.9% and 10.7%, respectively (p<0.001). The corresponding adjusted odds ratios were 1.00, 0.70 (95% CI 0.57 to 0.87) and 0.67 (95% CI 0.50 to 0.90). Physical activity was associated with BHR in all studied subgroups.

CONCLUSIONS

These results suggest that BHR is strongly and independently associated with decreased physical activity. Further studies are needed to determine the mechanisms underlying this association.

Airway reactivity to inhaled mannitol in cigarette smokers: a longitudinal study

Smoking induces airway hyperresponsiveness (AHR). Bronchial provocation with mannitol is used to identify AHR in subjects with asthma. This study aimed to determine the prevalence of airway hyperresponsiveness to mannitol in asymptomatic smokers compared to non-smokers and to assess if airway responsiveness to mannitol changes after smoking cessation. Airway responsiveness to inhaled mannitol was measured in smokers (n=42), and non-smokers (n=45). In smokers, the mannitol test was repeated 3 months after smoking cessation. Demographics including age, lung function and atopy status were similar for smokers and non-smokers (p=ns). Compared with non-smokers (2.2%), AHR to mannitol expressed by 15%> or = fall in FEV(1) was significantly more common in smokers (26.2%) (p=0.001). The provoking dose to induce a 15%> or = fall in FEV(1) (PD(15)), a measure of sensitivity, was median [IQR] 291 mg [207-377] in the 11 positive smokers. The response-dose ratio (RDR) (% fall in FEV(1)/cumulative dose), a measure of reactivity, was significantly higher in smokers (0.013 [0.006-0.029]) compared with non-smokers (0.004 [0.002-0.007]), (p<0.0001). After successful smoking cessation, the RDR decreased in most cases (p=0.01) and only one patient still recorded a 15% fall in FEV(1). None of the patients with a negative mannitol test turned positive, irrespective of the outcome of smoking cessation. AHR to mannitol is quite common in smokers compared to non-smokers and decreases significantly after smoking cessation. Thus, the mannitol test may be sensitive to non-asthmatic inflammation of the airways.

Impact of smoking on asthma therapy: a critical review of clinical evidence

Airway inflammation is central to the pathophysiology of asthma, with treatment directed towards modification of this inflammation and its consequences. The relationship between cigarette smoking and airway inflammation is also well described, but relatively little data are available on the potential influence of smoking on asthmatic airway inflammation and its treatment. While cigarette smoking is common in people with asthma, with prevalence rates similar to the general population, studies in asthma have tended to concentrate on individuals who have never smoked. However, there is recent evidence that smoking may confer a degree of corticosteroid resistance in asthma, and this review examines the relationship between asthma and cigarette smoking, with particular reference to the impact of smoking on the response to treatment of asthma. Smoking has a number of known influences on drug activity and metabolism, but the mechanism underlying corticosteroid resistance in asthmatic smokers is not yet clear, although there are differences in the nature of the airway inflammation in individuals with asthma who smoke compared with nonsmoking asthmatic patients. Encouragingly, there is some evidence that smoking cessation may at least partially restore corticosteroid responsiveness in asthmatic ex-smokers. Smoking cessation measures must be given a high priority in individuals with asthma who smoke.

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.

Lung function decline in laboratory animal workers: the role of sensitisation and exposure

BACKGROUND

Little is known about the relation between allergic sensitisation and subsequent long term lung function changes in working populations exposed to sensitising agents.

AIMS

To investigate whether exposure and work related sensitisation to laboratory animals are associated with lung function decline.

METHODS

The relation between exposure and sensitisation to laboratory animal allergens and changes in lung function was investigated in a longitudinal study (median follow up 2.0 years) among 319 laboratory animal workers. Subjects who had been working with laboratory animals for less than 4 years (n = 102) were analysed separately, since an earlier cross sectional analysis had suggested a strong healthy worker effect in more experienced workers.

RESULTS

In multiple regression analyses both sensitisation and exposure appeared to contribute independently to lung function decline in subjects who had been working with laboratory animals for less than 4 years, adjusting for gender, age, smoking, and atopy. Lung function decline was most pronounced in sensitised subjects who continued to be in contact with the animals to which they were sensitised, with estimated average excess declines in FEV1, FVC, and MMEF of 83 ml/y (p < 0.05), 148 ml/y (p < 0.01), and 7 ml/s/y (p = 0.9).

CONCLUSIONS

We conclude that exposure to laboratory animals is a significant risk factor for accelerated lung function decline, and that sensitised workers are especially at risk.

Specific sensitization to common allergens and pulmonary function in the European Community Respiratory Health Survey

BACKGROUND

The role of atopy in the evolution to chronic obstructive disease remains controversial.

AIM

We aimed to assess the association between individual sensitization to common allergens and lung function.

METHOD

We analysed data from 12,687 subjects aged 20 to 44 years, from 34 centres in 15 countries participating in the European Community Respiratory Health Survey (ECRHS). Participants performed a blood test, lung function test, methacholine challenge, and answered an administered questionnaire. The relationships between specific IgE, FEV1 and FEV1/FVC ratio were assessed for each study centre stratified by sex, followed by random effects meta-analysis.

RESULTS

Asthmatics sensitized to house dust mite had a lower FEV1 (-119 mL in women and -112 mL in men) and FEV1/FVC ratio (-1.95%, and -2.48%) than asthmatics without sensitization. Asthmatics sensitized to cat had a lower FEV1 (statistically significant for women only) and a lower FEV1/FVC ratio. Asthmatic women sensitized to grass had a lower FEV1 and a lower ratio, and those sensitized to Cladosporium had a lower FEV1. A weak association was found with sensitization to cat and to Cladosporium among non-asthmatic women, which disappeared after adjusting for BHR.

CONCLUSION

We conclude that atopy was related to a lower lung function, which was only apparent among asthmatics. This relationship was explained by specific sensitization to cat and to house dust mite, the latter being homogeneous across areas.

Effects of fluticasone propionate in COPD patients with bronchial hyperresponsiveness

BACKGROUND

Treatment of chronic obstructive pulmonary disease (COPD) with inhaled corticosteroids does not appear to be as effective as similar treatment of asthma. It seems that only certain subgroups of patients with COPD benefit from steroid treatment. A study was undertaken to examine whether inhaled fluticasone propionate (FP) had an effect on lung function and on indices of inflammation in a subgroup of COPD patients with bronchial hyperresponsiveness (BHR).

METHODS

Twenty three patients with COPD were studied. Patients had to be persistent current smokers between 40 and 70 years of age. Non-specific BHR was defined as a PC(20) for histamine of <or=8 mg/ml. Patients received either 2 x 500 microg FP or placebo for 6 months. Expiratory volumes were measured at monthly visits, BHR was determined at the start of the study and after 3 and 6 months, and bronchial biopsy specimens were taken at the start and after 6 months of treatment. Biopsy specimens from asymptomatic smokers served as controls.

RESULTS

In contrast to asthma, indices of BHR were not significantly influenced by treatment with FP. Forced expiratory volume in 1 second (FEV(1)) showed a steep decline in the placebo group but remained stable in patients treated with FP. FEV(1)/FVC, and maximal expiratory flows at 50% and 25% FVC (MEF(50), MEF(25)) were significantly increased in the FP treated patients compared with the placebo group. Biopsy specimens were analysed for the presence of CD3+, CD4+, CD8+, MBP+, CD15+, CD68+, CD1a, and tryptase cells. FP treatment resulted in marginal reductions in these indices of inflammation.

CONCLUSION

In patients with COPD and BHR, FP has a positive effect on indices of lung function compared with placebo. Bronchial inflammation analysed in bronchial biopsy specimens is only marginally reduced.

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 obstruction in relation to symptoms in chronic respiratory disease--a nationally representative population study

We examined the severity of airway obstruction and the occurrence of respiratory symptoms in a large, nationally representative population sample and in a subgroup of subjects with chronic bronchitis and/or emphysema to obtain information for developing national prevention and treatment strategies for these diseases. The study population comprised of 7217 randomly selected subjects (aged 30 years and older) who participated in a comprehensive health examination survey. The 'cases' were subjects diagnosed as having chronic bronchitis and/or emphysema. The survey methods comprised of questionnaires, interviews, physical measurements, including spirometry, and clinical examinations. In the whole study population, the age-adjusted prevalence of chronic bronchitis and/or emphysema was 22% among men and 7% among women, whilst clinically relevant airways obstruction (FEV1/FVC%< or = 69) was present in 11% of men and in 5% of women. The occurrence of chronic cough and phlegm production was lowest among the 'cases' with pronounced obstruction (in 68% of men with severe and in 60% of women with moderate obstruction), whereas cold air-associated dyspnoea aggravation showed an inverse relationship, occurring most commonly in men (80%) with severe obstruction. Unexpectedly, half of the bronchitic women had never smoked. We conclude that the occurrence of certain bronchitic symptoms, such as chronic cough and phlegm production and cold air-associated dyspnoea aggravation, may to some degree indicate different stages of the disease. Smoking was not closely associated with airflow limitation in women here.

Smoking and chronic obstructive pulmonary disease

Smoking is overwhelmingly the major cause of chronic bronchitis and emphysema worldwide. Additional risk factors for developing COPD are presented, along with the variables that govern cigarette smoke deposition in the lung. Major paradigms for the pathogenesis of COPD, including the protease-antiprotease and oxidant-antioxidant theories are described, and evidence for impaired reparative mechanisms in the causation of emphysema is noted. A description of the natural history of declining lung function in smokers and in the susceptible subset of smokers that ultimately develop smoking-induced COPD is accompanied by a discussion of the effects of smoking cessation on preservation of lung health. The disordered ventilation and gas-exchange physiology in the cigarette smoke-damaged lung is explained on the basis of the observed morphological changes.

Sensitization to individual allergens as risk factors for lower FEV1 in young adults. European Community Respiratory Health Survey

BACKGROUND

Atopy may impair ventilatory function, but results are controversial. We assess the association between individual reactivity to allergens and the level of baseline maximal one-second forced expiratory volume (FEV1), by smoking and respiratory symptoms.

METHODS

The 1472 participants (response 44.5%) of the five Spanish areas of the European Community Respiratory Health Survey (ECRHS) who performed respiratory function tests, skin prick tests and/or specific IgE against common aeroallergens (e.g. mites, pets, mould, pollens) are included. Bronchial hyperreactivity (BHR) was measured with a methacholine challenge.

RESULTS

After adjusting for BHR and smoking, in addition to the other allergens, skin reactivity to Alternaria (-208 ml; 95% CI :-451, 35) and IgE antibodies against cat (-124 ml; 95% CI:-269, 21) and Timothy grass (-115 ml, 95% CI:-190, -40) were associated with a decrease in FEV1 in females. Among males, skin reactivity to olive showed the strongest association (-111 ml; 95% CI: -261, 38). The associations were stronger in females. Smoking modifies the association for Alternaria and cat (P for interaction < 0.05). While cat is associated with a decrease in FEV1 in current smokers (-190 ml), Alternaria (-336 ml) was associated among never smokers. The exclusion of subjects with asthma symptoms, or adjustment for respiratory symptoms, led to similar results.

CONCLUSIONS

We conclude that immunoresponse to individual allergens (particularly outdoor) is associated with the level of FEV1, and this association occurred independently of asthma, and in smokers and non-smokers, which may be of interest in natural history of chronic obstructive pulmonary disease (COPD).

Risk factors from childhood to adulthood for bronchial responsiveness at age 32-42 yr

Bronchial responsiveness (BR) is an important risk factor for the development and outcome of asthma. This study assessed childhood risk factors for both the severity of BR in adulthood and either improvement or worsening of BR over time. Finally, we studied cross-sectional risk factors of BR in adulthood. Between 1966 and 1969, 119 allergic asthmatic children (5-14 yr of age) were studied. Of these, 101 (85%) subjects were reinvestigated at age 22-32 yr (visit 2), and at age 32-42 yr (visit 3). Spirometry, PC10 histamine, skin tests, blood eosinophils, and serum total IgE were measured and a questionnaire was used. Higher FEV1 values in childhood were associated with less severe BR at age 32-42 yr independent of other potential risk factors. Larger increases in FEV1 values both from visit 1 to 2 and from visit 2 to 3, a longer time interval from visit 1 to 3, and having pets in childhood were associated with less severe BR at age 32-42 yr. The same factors were found to be associated with less deterioration of BR from visit 2 to 3. In nonsmokers a higher IgE level at visit 2 was a risk factor for an increase in BR. At age 32-42 yr, a low level of lung function and the presence of asthma symptoms were associated with more severe BR, and older age and having pets were associated with less severe BR. IgE was related to more severe BR only in nonsmokers.

CONCLUSIONS

A lower lung function in childhood and less improvement in FEV1 over time were associated with more severe BR in adulthood.

Prospective study on the effect of smoking and nicotine substitution on leucocyte blood counts and relation between blood leucocytes and lung function

BACKGROUND

The influence of smoking and of nicotine substitution on the counts of total blood leucocytes and leucocyte subsets and the relations between the counts and lung function was investigated.

METHODS

The study was a combined cross sectional and prospective study of 298 smokers and 136 non-smokers. Forced expiratory volume in one second (FEV1) was measured in all participants at baseline and six months after quitting smoking in 160 ex-smokers (quitters) and 138 persons with smoking relapse. Blood samples were obtained from all participants at baseline and from 160 quitters and 30 continuing smokers two, six, 12, and 26 weeks after smoking cessation and from 92 quitters one year after the cessation of smoking.

RESULTS

Blood leucocyte counts and leucocyte subsets were all higher in smokers than in non-smokers. In cigarette smokers total leucocyte, neutrophil, and lymphocyte blood counts showed a dose dependent relationship with the daily cigarette consumption and pack years consumption. In smokers the neutrophil blood count was independently associated negatively with FEV1 residuals. After quitting smoking total leucocyte, neutrophil, and lymphocyte blood counts decreased during the first 26 weeks and after one year lymphocyte blood counts were higher than in non-smokers. In quitters substituted with nicotine chewing gum (2 mg) the accumulated number of pieces of chewing gum used in the 12 weeks had an inverse relationship with the decrease in the total lymphocyte blood count at 12 weeks after smoking cessation.

CONCLUSIONS

Leucocyte blood counts are raised in smokers and decrease after smoking cessation. Neutrophil blood counts had an inverse relationship with lung function and nicotine may increase lymphocyte blood counts in smokers.

Bronchial responsiveness and five-year FEV1 decline: a study in miners and nonminers

Increased nonspecific bronchial responsiveness (NSBR) may be a risk factor for the development of chronic airflow obstruction. We evaluated this hypothesis in a cohort of 378 underground coal miners and working nonminers. Methacholine testing was performed at the beginning and end of a 5-yr study period. Spirometry was repeated at 6-mo intervals and individual 5-yr FEV1 slopes were calculated by linear regression. Relationships between FEV1 slopes and NSBR were examined using multiple linear regression models, controlling for FEV1 level, smoking, and mining. Increasing NSBR at the initial survey was associated with a somewhat greater rate of subsequent FEV1 decline. Methacholine responders at the final survey had a considerably increased rate of decline during the previous years. Responsiveness status changed over the 5 yr in 22% of the subjects. Both the development and persistence of increased NSBR were strongly associated with higher rates of FEV1 decline. In contrast, FEV1 declines were not accelerated among workers with increased NSBR that reverted to normal. Smoking and mining were both independently associated with FEV1 declines, but did not substantially modify the effect of NSBR. Due to its variability over time, NSBR testing predicts lung function decline only in some individuals, and its value as a prognostic test for chronic airway disorders is limited. Because improvement in bronchial hyperresponsiveness was associated with a reduction in the rate of FEV1 loss, interventions directed at preventing or reducing nonspecific airway hyperresponsiveness should be investigated.

Blood eosinophil and monocyte counts are related to smoking and lung function

The aim of this study was to investigate the predictive value of peripheral eosinophil and monocyte blood counts regarding lung function in smokers and non-smokers, and to investigate the influence of smoking on these cell counts. Forced expiratory volume in 1 s (FEV1) measurements and blood samples were collected from 298 non-atopic smokers and 136 never-smokers. Blood samples were repeated in 160 smokers after cessation of smoking (quitters) and 30 continuing smokers, 2, 6, 12 and 26 weeks after smoking cessation. Monocyte (P < 0.05) but not eosinophil blood counts were higher in never-smokers compared to smokers. In never-smokers, blood eosinophil counts and monocyte counts correlated inversely (P < 0.05) and directly (P < 0.01), respectively, with standardized FEV1 residuals (FEVR). In smokers, blood eosinophil (P < 0.05) and monocyte (P < 0.05) counts correlated directly with FEVR independent of smoking history. After smoking cessation, monocyte blood counts (P < 0.05) increased. Both eosinophil and monocyte blood counts showed a greater increase in quitters with decreased lung function (P < 0.05). Former heavy smokers had higher blood eosinophil (P < 0.05) but lower monocyte (P < 0.05) count increase than had former light smokers. These data suggest that smoking influences eosinophil and monocyte blood counts and that this is associated with a small negative effect on lung function. Eosinophil blood counts had an opposite relation to lung function in smokers and non-smokers. Further research should include investigations of relations between smoking and stimulatory factors for recruitment and activity of eosinophils and monocytes.

Nonspecific airway hyperresponsiveness in HIV disease. Pulmonary Complications of HIV Infection Study Group

OBJECTIVES

HIV disease is frequently complicated by episodic acute bronchitis, suggesting the presence of chronic bronchial inflammation. To further examine this concept, we investigated the possible association of nonspecific airway hyperresponsiveness (AHR) and HIV disease.

DESIGN

Methacholine inhalation challenge studies were performed on 66 HIV-seropositive and 8 HIV-seronegative members of the Pulmonary Complications of HIV Infection Study Cohort. AHR was defined as 20% or more decline in FEV1 from the postdiluent value after inhalation of 125 or less cumulative breath units. The prevalence of AHR in HIV-seropositive cohort members was compared with that in matched control subjects who had undergone methacholine challenge testing for two unrelated studies. Demographic, behavioral, and clinical features in HIV cohort members with and without AHR were contrasted. The relationship between AHR and the occurrence of episodic airway disease or symptoms suggestive of airway disease was examined.

RESULTS

AHR was not more prevalent in HIV-seropositive cohort members than control subjects (19.3% vs 12.9%; p > 0.1). Within the cohort, AHR was detected more frequently in members with than without a history of asthma (60% vs 16%; p < 0.05). A greater proportion with than without AHR had 1 or more episode of pneumonia within 2 years (46% vs 9%; p < 0.01), 1 or more asthma episode during the study period (39% vs 1.9%; p < 0.001), or wheeze noted during clinic visits (62% vs 17%; p < 0.01). The proportion that experienced acute bronchitis did not differ in the two groups.

CONCLUSIONS

This study suggest that HIV-infected persons do not have increased prevalence of nonspecific AHR. In HIV disease, AHR is associated asthma, but not episodic acute bronchitis. Thus, the possibility that airway injury without demonstrable AHR might complicate HIV disease remains.

Interpretation of epidemiological surveys of asthma

Two particular issues make the interpretation of epidemiological studies in asthma problematic. The first is the lack of any clear definition of asthma. This is a perennial area of controversy. Thirty-eight years ago a Ciba Foundation guest symposium addressed this issue and suggested a solution. However, as J. G. Scadding, one of the participants of that symposium, pointed out after further consideration of the problem, what they had proposed was a description, not a definition. Since then, further attempts have been made but with little progress. They remain descriptive rather than definitive and have become, if anything, vaguer. The second problem has been the widespread failure to be precise about hypotheses or to define more precisely the hypothetical influences on asthma. Examples of this are the notions of 'inflammation' and 'atopy'. Standardization of methods for epidemiological studies of asthma is likely to provide a more rigorous framework for the comparison of results and the testing of hypotheses. Nevertheless, the development of such protocols should itself be seen as a hermeneutic device rather than an assertion of established knowledge.

Relationship of serum IgE concentration to level and rate of decline of pulmonary function: the Normative Aging Study

BACKGROUND

Previous reports on the relationship between serum immunoglobulin E (IgE) concentration and the level and rate of decline of pulmonary function in the general population have produced conflicting results. The relationship between total serum IgE concentration and pulmonary function was therefore examined in 1078 men aged 41-86 years followed in the Normative Aging Study.

METHODS

The serum IgE concentration determined at the start of the three year follow up period was examined in relation to both the level and longitudinal rate of decline of forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and FEV1/FVC.

RESULTS

In a cross sectional analysis restricted to subjects who had ever smoked cigarettes, multiple linear regression models indicated an inverse association between total serum IgE concentration and both FEV1 (beta = -0.090 1/log10 IU/ml; SE = 0.030; p < 0.005) and FVC (beta = -0.110 1/log10 IU/ml; SE = 0.034; p < 0.005) but not FEV1/FVC, after adjustment for age and height. This relationship persisted when individuals with diagnosed asthma or methacholine hyperresponsiveness were excluded. In subjects who had never smoked cigarettes the total serum IgE concentration was unrelated to spirometric indices. No association was observed in smokers or non-smokers between the serum IgE concentration measured at the beginning of the period of follow up and the decline in FEV1, FVC, or FEV1/FVC.

CONCLUSION

Increased levels of serum IgE measured at the beginning of the follow up period are associated with lower levels of pulmonary function but are not predictive of an accelerated rate in the decline of pulmonary function among middle aged and older men.

Airway responsiveness and job selection: a study in coal miners and non-mining controls

BACKGROUND

It has been suggested that health related job selection is a major cause of the healthy worker effect, and may result in inaccurate estimates of health risks of exposures in the working environment. Improved understanding of self selection, including the role of airway hyperresponsiveness, should improve accuracy in estimating occupational risks.

METHODS

We evaluated symptoms of the respiratory tract, lung function, occupational and smoking histories, and airway responsiveness from a cross sectional survey of 478 underground bituminous coal miners and non-mining controls. Workers with abnormal spirometry were excluded from methacholine testing.

RESULTS

Methacholine responsiveness (> or = 15% decline in forced expiratory volume in one second) was associated in both miners and controls with reduced ventilatory lung function and an increased risk of respiratory symptoms. Miners with the longest duration of work at the coal face had a low prevalence of methacholine responsiveness, compared with miners who had never worked at the coal face (12% v 39%, P < 0.01). Throughout their mining careers, miners who responded to methacholine were consistently less likely to have worked in dusty jobs than miners who did not respond to methacholine.

CONCLUSIONS

These results provide evidence that workers who are employed in dusty jobs are less likely than their unexposed coworkers to show increased non-specific airway responsiveness, presumably as a result of health related job selection. Surveys of workers in which responsiveness data are unavailable may underestimate the effects of dust exposure on respiratory health.

Asthmatic risk factors and bronchial reactivity in non-diagnosed asthmatic adults

Specific respiratory signs and symptoms are thought to occur prior to diagnoses of asthma as part of the natural history. These signs and symptoms include: high IgE, a history of wheezing symptoms, and/or excessive declines in lung function. The first two are thought to distinguish asthma from other airway obstructive diseases (AOD). To predict subsequent AOD, twelve years of follow-up (1972-84) data from the Tucson longitudinal epidemiological study of AOD in a community population were evaluated on 687 subjects aged 19-70 years on entry. To determine the likelihood that non-asthmatics that have these specific risk factors would have marked or intermediate bronchial reactivity to methacholine, an experimental study was performed. This was done in 1984-85 in a robust, efficient post-hoc stratified sample of male subjects ages 30-55 from the population followed from 1972. They were subsequently followed through 1991. Persistent symptoms best predicted final pulmonary function and new diagnosed AOD in subjects in the population. Previously diagnosed AOD also predicted lower pulmonary function. The experimental results indicate that predisposition to reactivity appears likely without the presence of diagnosed asthma. Further, the experimental subjects with high risk had increased symptomatology and decreased lung function when tested at follow-up; not all of the reactivity was explained by these factors. An attempt to predict reactivity by physician evaluation and special questionnaire was not fruitful. In addition, wheeze per se often disappeared without later evidence of asthma (or AOD) diagnosis, questioning some international tendencies to label all wheeze as asthma. Thus, high IgE significantly predicted bronchial responsiveness, but high IgE and symptoms are neither necessary nor sufficient. Also, both preclinical and clinical asthma predict eventual low lung function.

Total serum IgE and FEV1 by respiratory symptoms and obstructive lung disease in adults of a Norwegian community

BACKGROUND

The importance of total serum IgE level on lung function impairment has not been established in a general population.

OBJECTIVE

The aim of this cross-sectional community study was to examine the relationship between total serum IgE and level of lung function in adults, and whether this relationship differed by sex, age, smoking habits or by respiratory symptoms and disease status.

METHODS

A stratified random sample of 18-73 year old adults from the general population were invited to spirometry and serum analyses of total and specific IgE. Of 1512 subjects invited, 82% met and performed complete examinations.

RESULTS

Increasing level of total serum IgE was related to reduced lung function (P < 0.01) given as sex, age, and height standardized residuals of one second forced expiratory volume (SFEV1). Subjects with total serum IgE in the highest vs the lowest tertile had a mean SFEV1 of -0.28, corresponding to age and height adjusted FEV1 differences of 120 and 150 mL in women and men, respectively. The relationship between IgE and lung function impairment did not differ significantly by sex, age or smoking habits. In subjects with obstructive lung disease increasing level of total serum IgE was more negatively associated with lung function level than in subjects with respiratory symptoms alone. No relationship was observed in asymptomatic subjects. This was confirmed in a multiple linear regression analysis adjusting for sex, age, smoking habits and lifetime smoking consumption showing that SFEV1 was predicted by an interaction between total serum IgE level and symptom and disease status (P < 0.01). This interaction remained after excluding subjects (n = 105) having specific IgE antibodies.

CONCLUSION

Increasing total serum IgE level was associated with progressively lower lung function in a general adult population after taking other predictors of impaired spirometric lung function into account, though dependent on the subjects' respiratory symptom and disease status. Variation in prevalences of respiratory symptoms and obstructive lung disease in previous examined populations may thus explain conflicting observations of the association between total IgE and airflow impairment.

Ageing, late-onset asthma and the beta-adrenoceptor

Late-onset asthma in old age is a common clinical problem. There are similarities between receptor and post-receptor beta 2-adrenoceptor abnormalities reported in young asthmatics and in elderly normal subjects. Recent evidence lends some support to the idea of the 'aging' beta 2-adrenoceptor as a contributory factor in the development of late-onset asthma, although questions of the validity of the peripheral mononuclear cell model and of receptor tachyphylaxis to intrinsic and extrinsic beta-adrenoceptor agonists remain unresolved. Further work should focus on in vivo studies of airway receptor function and on beta 2-adrenoceptor-mediated pathways other than smooth muscle-related bronchoconstriction.

Factors affecting peak expiratory flow variability and bronchial reactivity in a random population sample

BACKGROUND

Bronchial reactivity measurements are widely used in epidemiological studies to provide an objective marker of asthma. There are, however, several potential advantages of measuring peak expiratory flow (PEF) variability instead, particularly in large studies. PEF variability and bronchial reactivity were compared in a population sample to assess the relationships of the two measurements to factors known to be associated with airways disease, and to compare their response rates.

METHODS

Subjects aged 18-65 were randomly selected from the electoral register of an administrative area in eastern England and randomised to attend either for a bronchial challenge test measuring the provocative dose of methacholine producing a 20% fall in FEV1 (PD20), or to measure PEF at two hourly intervals during waking hours for one week. Skin tests with common allergens were performed and a smoking history obtained. PEF variability was expressed as the amplitude % mean (highest - lowest x 100/mean).

RESULTS

A total of 273 subjects (69%) collected a PEF meter but a completed record sheet was returned by only 247 (62%); this was still significantly more than the 202 subjects (54%) who attended for and successfully completed a challenge test. Amplitude % mean was higher in women than in men (9.7% v 8.5%). In multiple regression analysis amplitude % mean increased significantly with age, mean skin weal diameter, and with current smoking. The odds of having a PD20 below 24.5 mumol increased with mean skin weal diameter and were greater in current smokers. Neither age nor sex had a significant effect on bronchial reactivity but there were significant interactions between age and the effects of both smoking and atopy.

CONCLUSIONS

The higher response rate associated with the use of PEF variability measurement, and the association with factors implicated in the pathogenesis of airways disease, suggest that PEF variability would be a useful measurement to employ in epidemiological studies.

Bronchial reactivity, lung function, and serum immunoglobulin E in smoking-discordant monozygotic twins

Smokers with chronic bronchitis and/or chronic obstructive pulmonary disease (COPD) have been reported to have an increased bronchial reactivity (BR). It has been discussed whether increased BR is a risk factor for the development of COPD in smokers. We studied 10 monozygotic twin pairs who were discordant for tobacco smoking by means of histamine provocation tests, lung function tests, and serum samples for total IgE. The smokers had a mild obstructive ventilatory impairment, with FEV1 significantly lower than that of the partner both when it was determined from the flow-volume loops (3.2 +/- 1.0 L for smokers and 3.4 +/- 0.8 L for nonsmokers) and by the Vitalograph spirometer (3.5 +/- 1.0 L for smokers and 3.8 +/- 0.8 L for nonsmokers). Forced midexpiratory flow (FEF25-75%) and forced expiratory flow at 75 to 85% of vital capacity (FEF75-85%) were both significantly lower in the smokers (p < 0.05). The alveolar plateau phase N2-delta test and lung clearing index in the multibreath nitrogen washout test were both significantly affected in the smokers (p < 0.05 and p < 0.01, respectively). We found no significant difference in histamine reactivity between smokers and nonsmokers and no correlation between differences in reactivity and differences in lung function within pairs. Total serum IgE was significantly higher in the smokers than in their nonsmoking siblings. These data suggest that obstructive ventilatory impairment and raised serum IgE are earlier and more constant manifestations of tobacco smoking than increased bronchial reactivity. Thus, bronchial hyperreactivity does not seem to be a major risk factor for the development of early airways obstruction in smokers.

Risk factors for ventilatory impairment among middle-aged and elderly men. The Normative Aging Study

To evaluate the relationship of atopy and inflammation to the occurrence of ventilatory impairment, we studied 1,301 middle-aged and older men participating in the Normative Aging Study at the time of their 1984 to 1987 examination. Screening at entry to the study in the 1960s had excluded subjects with asthma and other chronic diseases at that time. After adjustment for smoking status and pack-years in this cross-sectional analysis, a weak inverse relationship between FEV1 and blood eosinophil count was not statistically significant, and FEV1 showed no relationship to blood eosinophil count as a percentage of total leukocytes. A weak inverse relationship between FEV1 and serum total IgE concentration was not statistically significant. Cutaneous immediate hypersensitivity to one or more common aeroallergens was not related to FEV1. A significant inverse relationship between FEV1 and blood total leukocyte count was observed in never and former smokers. FEV1 was significantly lower in subjects reporting usual phlegm production. These findings suggest that ventilatory impairment is not related to atopic status among middle-aged and older men without a history of asthma. The inverse relationship between total leukocyte count and FEV1 in this sample supports the hypothesis that nonallergic inflammation plays a role in the pathogenesis of chronic airflow obstruction in this group.

Respiratory symptoms in young adults should not be overlooked

The purpose of this study was to examine the relation between development of respiratory symptoms and the rate of change in ventilatory lung function in young adults during a study period of 8 yr. The study population consisted of 391 subjects who were 15 to 40 yr of age at initial examination, when they underwent spirometry and an interviewer-administered ATS-DLD-78-A questionnaire on respiratory health, and who were reexamined 8 yr later. The association between the development of symptoms and the rate of change in FEV1 over time (delta FEV1, ml/yr) was studied in a linear regression model that included the potential confounders and other determinants of the outcome. The presence of modification by such factors as smoking, childhood exposure to environmental tobacco smoke, gender, or atopy was assessed by the significance of interaction terms between potential modifiers and incident symptoms. Subjects who developed wheezing and dyspnea and in whom a doctor diagnosed asthma had a significantly greater average annual change in FEV1 compared with those without respiratory symptoms or asthma (-12.3 ml/yr, SE 5.0; -16.2 ml/yr, SE 5.5; and -42.6 ml/yr, SE 11.5, respectively). When focusing on subjects without a diagnosis of asthma, the associations with appearance of wheezing and dyspnea remained significant. The associations were in general stronger in never smokers compared with smokers and were strongest in ex-smokers. The presence of atopy was a significant modifier, so that in subjects with atopy there was a stronger negative association between the onset of cough and asthma and delta FEV1 than in those without.(ABSTRACT TRUNCATED AT 250 WORDS)

Peripheral blood leukocyte count and respiratory symptoms

The relationship of peripheral blood leukocyte count to respiratory symptoms was explored in data from the Second Annual National Health and Nutrition Survey (NHANES II). The study sample consisted of 9237 white and nonwhite US adults between the ages of 30 and 74 years. Three respiratory symptom outcomes were utilized: physician-diagnosed chronic cough and chronic bronchitis and self-reported frequent wheeze apart from colds or flu in the past 12 months. Peripheral blood leukocyte counts were performed using a Coulter counter, model FN. Logistic regression analysis was performed for each of the three respiratory symptom outcomes controlling for age, race, gender, and cigarette-years of smoke exposure. The peripheral blood leukocyte count was a significant predictor for each symptom. For a standard deviation increase in the log leukocyte count, the relative odds of wheezing was 1.93 (95% confidence level [CI], 1.47 to 2.52); for chronic cough, 2.29 (95% CI, 1.74 to 3.00); and for bronchitis, 2.44 (95% CI, 1.77 to 3.35). Analyses restricted to never smokers gave similar results. These data suggest that peripheral blood leukocyte count correlates with respiratory symptoms and are consistent with the hypothesis that the leukocyte count is a serum marker of inflammation.