The relationship of eosinophilia and positive skin test reactivity to respiratory symptom prevalence in a community-based population study

Blood eosinophil count in the general population: typical values and potential confounders

There is growing interest in blood eosinophil counts in the management of chronic respiratory conditions such as asthma and chronic obstructive pulmonary disease (COPD). Despite this, typical blood eosinophil levels in the general population, and the impact of potential confounders on these levels have not been clearly defined.We measured blood eosinophil counts in a random sample of 11 042 subjects recruited from the general population in Austria. We then: 1) identified factors associated with high blood eosinophil counts (>75th percentile); and 2) excluded subjects with these factors to estimate median blood eosinophil counts in a "healthy" sub-population (n=3641).We found that: 1) in the entire cohort, age ≤18 years (OR 2.41), asthma (OR 2.05), current smoking (OR 1.72), positive skin prick test (OR 1.64), COPD (OR 1.56), metabolic syndrome (OR 1.41), male sex (OR 1.36) and obesity (OR 1.16) were significantly (p<0.05) associated with high blood eosinophil counts (binary multivariable logistic regression analysis), and had an additive effect; and 2) after excluding these factors, in those older than 18 years, blood eosinophil counts were higher in males than in females (median 120 (5%-95% CI: 30-330) versus 100 (30-310) cells·µL^-1, respectively) and did not change with age.Median blood eosinophil counts in adults are considerably lower than those currently regarded as normal, do not change with age beyond puberty, but are significantly influenced by a variety of factors which have an additive effect. These observations will contribute to the interpretation of blood eosinophil levels in clinical practice.

Isolation, Formulation, and Efficacy Enhancement of Morin Emulsified Carriers Against Lung Toxicity in Rats

The present study demonstrates a preparative medium-pressure liquid chromatography (MPLC) method for isolation of Morin besides evaluating its efficacy in comparison with its self-nanoemulsifying drug delivery (SNEDD) and nanoemulsion (NE) systems against in-vivo HgCl₂-induced lung toxicity in rats. Morin was isolated from hydroalcoholic (70%) extract of Psidium guajava leaves by MPLC. The purity (> 90%) was done using HPLC. Screening of Morin solubility was studied to identify the components of each system. The prepared formulae were assessed for their thermodynamic stability, rheological properties, emulsification time, size, zeta potential beside its dissolution. The selected formulae according to the smallest size, highest zeta potential, and release at Q_10 min were assessed for their morphology by transmission electron microscopy (TEM) and protective potential against in-vivo HgCl₂-induced lung toxicity in rats. All formulae were stable with Newtonian flow, emulsification time was (< 134 ± 10 s), size (< 40 nm) with zeta potential (> - 10.36 ± 0.99 mV). The extent of free Morin dissolved from capsule showed significantly the lowest percent released (22.21 ± 1.45%) while in case of SNEDDs and NEs (> 55% dissolved). The morphology of the selected Morin formulae showed spherical shape within the nano-range. Supplementation of Morin and its formulae to rats caused significant decrease in C-reactive protein, hepatoglobin, hydroproxide, lung nitric oxide, tumor necrosis factor-α, immunoglobulin (E and G), histamine, malondialdehyde, and interleukin-6 gene expression while significant increase in immunoglobulin A, caspase-3, catalase, and glutathione peroxidase compared to HgCl₂. SNEDD and NE formulae could ameliorate lung toxicity in a mechanism related to their antioxidant and anti-inflammatory potential.

Non-typeable Haemophilus Influenzae detection in the lower airways of patients with lung cancer and chronic obstructive pulmonary disease

Background

Chronic airway inflammation and hypersensitivity to bacterial infection may contribute to lung cancer pathogenesis. Previous studies have demonstrated that nontypeable Haemophilus influenzae (NTHi) is the most common colonizing bacteria in the lower airways of patients with COPD. The objective of this study was to determine the presence of NTHi and immunoglobulin concentrations in patients with lung cancer, COPD and controls.

Methods

Serum and bronchial wash samples were collected from patients undergoing diagnostic bronchoscopy. Total IgE, IgG and specific NTHi IgG were measured by enzyme linked immunosorbent assay. Bronchial wash samples were examined for the presence of NTHi via PCR.

Results

Out of the 60 patients: 20 had confirmed Lung Cancer, 27 had COPD only and 13 were used as Controls. NTHi was detected in the lower airways of all three groups (Lung Cancer 20%; COPD 22% and Controls 15%). Total IgE was highest in Lung Cancer subjects followed by COPD and control subjects (mean ± SD: 870 ± 944, 381 ± 442, 159 ± 115). Likewise total IgG was higher in Lung cancer (Mean ± SD: 6.99 ± 1.8) patients compared to COPD (Mean ± SD: 5.43 ± 2).

Conclusions

The lack of difference in NTHi and specific antibodies between the three groups makes it less likely that NTHi has an important pathogenetic role in subjects with Lung Cancer. However the detection of higher IgE antibody in Lung Cancer subjects identifies a possible mechanism for carcinogenesis in these subjects and warrants further study.

Electronic supplementary material

The online version of this article (10.1186/s40248-018-0123-x) contains supplementary material, which is available to authorized users.

Atopy in people aged 40 years and over: Relation to airflow limitation

BACKGROUND

Previous studies have reached conflicting conclusions about the role of atopy as a risk factor for COPD. In part, this is attributable to variation in the definitions of airflow limitation and the treatment of people with asthma.

OBJECTIVE

To establish whether there is any independent association between atopy and post-bronchodilator airflow limitation in the general population aged 40 years and over.

METHODS

A cross-sectional survey was conducted in a general population sample of 2415 people aged 40 years and over in Australia. A history of ever being diagnosed with asthma was elicited by questionnaire. Atopy was defined as any skin prick test weal to common aeroallergens ≥4 mm. Airflow limitation was defined as post-bronchodilator spirometric (FEV₁ /FVC) ratio <lower limit of normal. Analyses were adjusted for potential confounding due to age, sex, smoking, race and socio-economic status.

RESULTS

The prevalence of atopy, ever diagnosed asthma and post-bronchodilator airflow obstruction was 44.8%, 19.3% and 7.5%, respectively. In the population as a whole, atopy was associated with lower FEV₁ (adjusted difference -0.068L, 95% confidence interval (CI) -0.104 to -0.032), FVC (adj. difference -0.043L, 95% CI -0.086 to -0.0009) and post-bronchodilator FEV₁/FVC ratio (adj. difference -0.011, 95% CI -0.017 to -0.0055). The effect of atopy on lung function was no longer apparent when participants who reported ever diagnosed asthma were excluded (FEV₁ -0.011L, [95% CI -0.05 to 0.028L], FVC -0.012L [95% CI -0.060 to 0.036] and FEV₁/FVC ratio -0.0012 [95% CI -0.0072 to 0.0047L]).

CONCLUSION AND CLINICAL RELEVANCE

The apparent association between atopy and post-bronchodilator airflow limitation in the general population appears to be explained by the association between atopy and having ever diagnosed asthma and the effect of asthma on lung function.

Defining Chronic Cough: A Systematic Review of the Epidemiological Literature

Purpose

Recent evidence suggests a global burden of chronic cough in general populations. However, the definitions vary greatly among epidemiological studies, and none have been validated for clinical relevance. We aimed to examine previous epidemiological definitions in detail and explore the operational characteristics.

Methods

A systematic review was conducted for epidemiological surveys that reported the prevalence of chronic cough in general adult populations during the years 1980 to 2013. A literature search was performed on Pubmed and Embase without language restriction. Epidemiological definitions for chronic cough were classified according to their components, such as cutoff duration. Meta-analyses were performed for the male-to-female ratio of chronic cough prevalence to explore operational characteristics of epidemiological definitions.

Results

A total of 70 studies were included in the systematic review. The most common epidemiological definition was identified as 'cough ≥3 months' duration without specification of phlegm (n=50); however, it conflicted with the cutoff duration in current clinical guidelines (cough ≥8 weeks). Meta-analyses were performed for the male-to-female ratio of chronic cough among 28 studies that reported sex-specific prevalence using the most common definition. The pooled male-to-female odds ratio was 1.26 (95% confidence interval 0.92-1.73) with significant heterogeneity (I²=96%, P<0.001), which was in contrast to clinical observations of female predominance from specialist clinics. Subgroup analyses did not reverse the ratio or reduce the heterogeneity.

Conclusions

This study identified major issues in defining chronic cough in future epidemiological studies. The conflict between epidemiological and clinical diagnostic criteria needs to be resolved. The unexpected difference in the gender predominance between the community and clinics warrants further studies. Clinical validation of the existing definition is required.

Objective allergy markers and risk of cancer mortality and hospitalization in a large population-based cohort

Purpose

There are indications that a history of allergy may offer some protection against cancer. We studied the relation of three objectively determined allergy markers with cancer mortality and hospitalization risk.

Methods

Associations between three allergy markers (number of peripheral blood eosinophil counts, skin test positivity, and serum total IgE) with mortality and hospitalization from any type and four common types of cancer (lung, colorectal, prostate, and breast cancer) were assessed in the Vlagtwedde–Vlaardingen cohort (1965–1990), with follow-up of mortality until 31 December 2008. Hospitalization data were available since 1 January 1995.

Results

There were no significant associations between objective allergy markers and cancer mortality or hospitalization. We found several associations in specific subgroups. A higher number of eosinophils was associated with a decreased risk of colorectal cancer mortality in ever smokers HR (95 % CI) = 0.61 (0.45–0.83) and in males 0.59 (0.42–0.83); however, no overall association was observed 0.84 (0.64–1.09). Skin test positivity was associated with a decreased risk of any cancer mortality only among females 0.59 (0.38–0.91) and showed no overall association 0.83 (0.67–1.04). Serum total IgE levels were associated with an increased risk of lung cancer mortality among females 4.64 (1.04–20.70), but with a decreased risk of cancer hospitalization in ever smokers 0.77 (0.61–0.97) and males 0.72 (0.55–0.93); however, no overall associations were observed [mortality 0.99 (0.79–1.25), and hospitalization 0.86 (0.71–1.04)].

Conclusions

We found no associations between objective allergy markers and cancer in the total population. However, skin test positivity and a high number of eosinophils were associated with a reduced risk to die of cancer in specific subgroups. Hence, it seems important to study specific subgroups defined by gender and smoking habits in order to identify allergy markers of predictive value for cancer mortality.

Electronic supplementary material

The online version of this article (doi:10.1007/s10552-014-0489-9) contains supplementary material, which is available to authorized users.

Atopy is a risk factor for respiratory symptoms in COPD patients: results from the EUROSCOP study

BACKGROUND

The pathogenesis of COPD is complex and remains poorly understood. The European Respiratory Society Study on Chronic Obstructive Pulmonary Disease (EUROSCOP) investigated long-term effects of budesonide; 18% of the COPD participants were atopic. So far effects of atopy on the long-term course of COPD have not been elucidated.

METHODS

Factors related to the presence of atopy (positive phadiatop) in 1277 mild-to-moderate COPD patients participating in EUROSCOP were analysed using regression analysis. Incidence and remission of respiratory symptoms during 3-year follow-up were analysed using generalised estimating equations models, and association of atopy with lung function decline using linear mixed effects models.

RESULTS

Independent predisposing factors associated with the presence of atopy were: male gender (OR: 2.21; 95% CI: 1.47-3.34), overweight/obese (OR: 1.41; 95% CI: 1.04-1.92) and lower age (OR: 0.98; 95% CI: 0.96-0.99). Atopy was associated with a higher prevalence of cough (OR: 1.71; 95% CI: 1.26-2.34) and phlegm (OR: 1.50; 95% CI: 1.10-2.03), but not with lung function levels or FEV1 decline. Atopic COPD patients not treated with budesonide had an increased incidence of cough over time (OR: 1.79, 95% CI: 1.03-3.08, p = 0.038), while those treated with budesonide had increased remission of cough (OR: 1.93, 95% CI: 1.11-3.37, p = 0.02) compared to non-atopic COPD patients.

CONCLUSIONS

Atopic COPD patients are more likely male, have overweight/obesity and are younger as compared with non-atopic COPD patients. Atopy in COPD is associated with an increased incidence and prevalence of respiratory symptoms. If atopic COPD patients are treated with budesonide, they more often show remission of symptoms compared to non-atopic COPD patients who are treated with budesonide. We recommend including atopy in the diagnostic work-up and management of COPD.

Serum IgE and eosinophil count in allergic rhinitis--analysis using a modified Bayes' theorem

BACKGROUND

To use probability theory to establish threshold values for total serum IgE and eosinophil counts that support a diagnosis of allergic rhinitis and to compare our results with previously published data.

METHODS

Prospective study of rhinitis patients using a modified version of Bayes' theorem. Study included 125 patients at the West Los Angeles VA Medical Center diagnosed with rhinitis who completed allergy consultation and immediate hypersensitivity skin testing.

RESULTS

Eighty-nine of 125 patients were atopic by prick and/or intradermal skin testing. Using a modified version of Bayes' theorem and positive and negative probability weights, calculations for different thresholds of serum IgE and eosinophil counts were summated and a posttest probability for atopy was calculated. Calculated posttest probabilities varied according to the threshold used to determine a positive or negative test; however, IgE thresholds greater than 140IU/ml and eosinophil counts greater that 80cells/ml were found to have a high probability of predicting atopy in patients with rhinitis. Moreover, IgE had a greater influence than eosinophil count in determining posttest probability of allergy in this population. Considerable differences were noted in the IgE levels of atopic and non-atopic patients, including those with asthma or a history of smoking. However, these differences were not observed with eosinophil levels.

CONCLUSIONS

Using a modified version of Bayes' theorem to determine posttest probability, IgE threshold levels greater than 140IU/ml and eosinophil counts greater than 80cells/ml in an individual with clinical signs and symptoms of rhinitis are likely to correlate with an atopic aetiology. This model of probability may be helpful in evaluating individuals for diagnostic skin testing and certain types of allergy-modifying treatment.

Evaluation of the immunity activity of glycyrrhizin in AR mice

In this study, we evaluated effect of glycyrrhizin on immunity function in allergic rhinitis (AR) mice. The AR mice model were induced by dripping ovalbumin in physiological saline (2 mg mL⁻¹, 10 μL) into the bilateral nasal cavities using a micropipette. After the AR model was induced, mice were randomly divided into six groups: the normal control, model, lycopene 20 mg kg⁻¹ (as positive control drug) group, and glycyrrhizin 10, 20, 30 mg kg⁻¹ groups. After the sensitization day 14, lycopene (20 mg/kg BW) and glycyrrhizin (10, 20 and 30 mg/kg BW) were given orally for 20 days once a day. Mice in the normal control and model groups were given saline orally once a day for 20 days. Results showed that glycyrrhizin treatment could dose-dependently significantly reduce blood immunoglobulin E (IgE), interleukin-4 (IL-4), interleukin-5 (IL-5), interleukin-6 (IL-6), nitrous oxide (NO), tumor necrosis factor-alpha (TNF-α) levels and nitrous oxide synthase (NOS) activity and enhance blood immunoglobulin A (IgA), immunoglobulin G (IgG), immunoglobulin M (IgM), interleukin-2 (IL-2) and interleukin-12 (IL-12) levels in AR mice. Furthermore, glycyrrhizin treatment could dose-dependently significantly enhance acetylcholinesterase (AchE) activity and reduce substance P (SP) level in peripheral blood and nasal mucosa of AR mice. We conclude that glycyrrhizin can improve immunity function in AR mice, suggesting a potential drug for the prevention and therapy of AR.

Nicotine inhibits Fc epsilon RI-induced cysteinyl leukotrienes and cytokine production without affecting mast cell degranulation through alpha 7/alpha 9/alpha 10-nicotinic receptors

Smokers are less likely to develop some inflammatory and allergic diseases. In Brown-Norway rats, nicotine inhibits several parameters of allergic asthma, including the production of Th2 cytokines and the cysteinyl leukotriene LTC(4). Cysteinyl leukotrienes are primarily produced by mast cells, and these cells play a central role in allergic asthma. Mast cells express a high-affinity receptor for IgE (FcepsilonRI). Following its cross-linking, cells degranulate and release preformed inflammatory mediators (early phase) and synthesize and secrete cytokines/chemokines and leukotrienes (late phase). The mechanism by which nicotine modulates mast cell activation is unclear. Using alpha-bungarotoxin binding and quantitative PCR and PCR product sequencing, we showed that the rat mast/basophil cell line RBL-2H3 expresses nicotinic acetylcholine receptors (nAChRs) alpha7, alpha9, and alpha10; exposure to exceedingly low concentrations of nicotine (nanomolar), but not the biologically inactive metabolite cotinine, for > or = 8 h suppressed the late phase (leukotriene/cytokine production) but not degranulation (histamine and hexosaminidase release). These effects were unrelated to those of nicotine on intracellular free calcium concentration but were causally associated with the inhibition of cytosolic phospholipase A(2) activity and the PI3K/ERK/NF-kappaB pathway, including phosphorylation of Akt and ERK and nuclear translocation of NF-kappaB. The suppressive effect of nicotine on the late-phase response was blocked by the alpha7/alpha9-nAChR antagonists methyllycaconitine and alpha-bungarotoxin, as well as by small interfering RNA knockdown of alpha7-, alpha9-, or alpha10-nAChRs, suggesting a functional interaction between alpha7-, alpha9-, and alpha10-nAChRs that might explain the response of RBL cells to nanomolar concentrations of nicotine. This "hybrid" receptor might serve as a target for novel antiallergic/antiasthmatic therapies.

Response to budesonide among atopic and non-atopic infants/preschoolers with recurrent wheezing

BACKGROUND

The treatment in non-atopic young children with recurrent wheezing remains controversial.

OBJECTIVE

The aim of the study was to compare the response of inhaled budesonide in atopic versus non-atopic infants/preschoolers with recurrent wheezing (more than three episodes in the last year or one episode per month in the last three months).

METHODS

One hundred and seventy three infants/preschoolers (mean age 1.58+/-0.9 yrs) with recurrent wheezing without previous use of inhaled corticosteroids were enrolled and divided into two categories: atopics (eosinophils in peripheral blood > or =4%) and non-atopics (<4%). Both groups were treated with budesonide (200 mcg bid delivered by MDI and spacer) for three months. The primary outcome was the prevalence of wheezing exacerbation episodes at the end of the treatment.

RESULTS

Thirty-seven out of 173 (21.4%) were atopics and they were significantly younger, more frequently with a father with asthma, maternal grandparents with asthma and rhinitis, paternal and maternal grandparents with eczema, and higher number of wheezing episodes in the last year than non-atopics. At the end of the study, among those with good compliance (>70% of the weekly doses), the proportion of wheezing episodes were similar among atopics and non-atopics (57.7% vs. 44.1%, p=0.25, respectively); the number of exacerbations requiring emergency department (ED) visits and hospital admission were also similar.

CONCLUSION

Regular budesonide therapy may decrease the episodes of wheezing in infants/preschoolers with recurrent wheezing, independently of atopy.

Asthma in Latin America: the dawn of a new epidemic

PURPOSE OF REVIEW

Asthma is a heterogeneous disease with high morbidity worldwide. Unlike the low prevalence of asthma and allergy found in many developing countries, especially in rural settings, its prevalence in Latin America is high. In these sites, nonatopic asthma seems to be the most common phenotype observed among school-age children. Therefore, it seems that asthma in Latin America has some particular characteristics that will be presented and discussed in this article.

RECENT FINDINGS

The prevalence of asthma-like symptoms in childhood is high in many populations studied in Latin America with similar frequencies to those reported in more developed countries. However, the mechanisms and risk factors associated with nonatopic asthma, which is the most prevalent phenotype in this region, have been scarcely studied.

SUMMARY

The better understanding of asthma phenotypes that prevail in Latin America and the investigation of determining factor studies may help establish new diagnostic and therapeutic approaches. These findings should affect public health policies for this new asthma epidemic through the combination of the atopic and nonatopic phenotypes. We hope that this article sheds some new light into these important and most relevant questions.

The course of persistent airflow limitation in subjects with and without asthma

RATIONALE

Most patients who develop persistent airflow limitation do so either as a manifestation of chronic obstructive pulmonary disease that is largely related to smoking or as a consequence of persistent asthma. We sought to compare the natural course of lung function associated with persistent airflow limitation in subjects with and without asthma from early to late adult life.

METHODS

We studied 2552 participants aged 25 or more who had multiple questionnaire and lung function data from the long-term prospective population-based Tucson Epidemiological Study of Airway Obstructive Disease. Persistent airflow limitation was defined as FEV(1)/FVC ratio consistently < 70% in all completed surveys subsequent to the first survey with airflow limitation. Participants were divided into nine groups based on the combination of their physician-confirmed asthma status (never, onset < or = 25 years, or onset > 25 years) and the presence of airflow limitation during the study follow-up (never, inconsistent, or persistent).

RESULTS

Among subjects with an asthma onset < or = 25 years, blood eosinophilia increased significantly the odds of developing persistent airflow limitation (adjusted ORs: 3.7, 1.4-9.5), whereas cigarette smoking was the strongest risk factor for persistent airflow limitation among non-asthmatics and among subjects with asthma onset after age 25 years. Among subjects with persistent airflow limitation, the natural course of lung function differed between subjects with asthma onset < or = 25 years and non-asthmatics, with the former having lower FEV(1) levels at age 25 (predicted value for a 175-cm tall male of 3400 versus 4090 ml, respectively; p<0.001) and the latter having greater FEV(1) loss between age 25 and 75 (1590 versus 2140 ml; p=0.003).

CONCLUSION

In subjects who have asthma onset before 25 years of age and persistent airflow limitation in adult life, the bulk of the FEV(1) deficit is already established before age 25 years.

Nested case-control study on associations between lung function, smoking and mortality in Japanese population

OBJECTIVES

Only a few long-term follow-up studies with a focus on the association between lung function and mortality in the Japanese population have been undertaken. In this study, we examined the associations of lung function, smoking and the results of allergy skin tests with mortality in a longitudinal study of the Japanese population.

METHODS

Baseline measurements were performed on residents of Fukui, Japan in 1972, and a follow-up survey was conducted in 2002. By employing a nested case-control design, 596 cases (deaths) and 596 age and sex-matched controls (survivals) were selected. Lung function was assessed using forced vital capacity (FVC) expressed as the normal percent predicted (FVC %pred) and the ratio of forced expiratory volume in 1 second (FEV(1)) to FVC (FEV(1)/FVC). Allergy skin tests were performed with extracts of house dust, candidia and mixed fungal samples (bronchomycosis). The Brinkman index was used to assess smoking intensity. The Cox proportional hazards model was used to evaluate whether lung function was associated with mortality after adjustment for other potential confounding variables.

RESULTS

Those categorized into the first- or second-lowest quartile of FVC %pred had a higher mortality [hazard ratios (HRs) and 95% confidence intervals (CIs): 2.01 (1.26-3.19) and 1.84 (1.11-3.05)], respectively. On top of these, heavy smoking (BI≥400) was associated with a higher mortality [HR and 95% CI: 1.73 (1.18-2.53)]. There were only weak of associations between the results of allergy skin tests and mortality.

CONCLUSIONS

These results suggest that FVC %pred of lung function and smoking can serve as long-term independent predictors of mortality.

Blood eosinophils in workers with aluminum potroom asthma are increased to higher levels in non-smokers than in smokers

BACKGROUND

Aluminum potroom asthma (PA) has been described in several reports. This study aimed to investigate the association between blood eosinophils and PA.

METHODS

In a cross-sectional study, 338 workers were examined as follows: spirometry, blood eosinophils, skin prick test, and work exposure measurements. They also completed a questionnaire on respiratory symptoms, smoking, allergy, and duration of work exposure.

RESULTS

The odds ratio for PA was 4.2 (95% confidence interval 1.5-9.7) for workers with eosinophils > or =400 x 10(6) cells/L compared with workers with eosinophils <200 x 10(6) cells/L. In non-smokers, the number of eosinophils was 177 x 10(6) cells/L (P < 0.001) higher among workers with PA than asymptomatic workers, whereas the corresponding difference among current smokers was only 63 x 10(6) cells/L (P = 0.03).

CONCLUSIONS

The prevalence of PA was positively associated with blood eosinophils. An attenuation of the blood eosinophil increase was observed in smoking asthmatics, suggesting an immune-modulating effect of smoking.

Characterisation of atopic and non-atopic wheeze in 10 year old children

BACKGROUND

Wheezing occurs in both atopic and non-atopic children. The characteristics of atopic and non-atopic wheeze in children at 10 years of age were assessed and attempts made to identify whether different mechanisms underlie these states.

METHODS

Children were seen at birth and at 1, 2, 4 and 10 years of age in a whole population birth cohort study (n = 1456; 1373 seen at 10 years). Information was collected prospectively on inherited and early life environmental risk factors for wheezing. Skin prick testing, spirometry, and methacholine bronchial challenge were conducted at 10 years. Wheezing at 10 years of age was considered atopic or non-atopic depending on the results of the skin prick test. Independent significant risk factors for atopic and non-atopic wheeze were determined by logistic regression.

RESULTS

Atopic (10.9%) and non-atopic (9.7%) wheeze were equally common at 10 years of age. Greater bronchial hyperresponsiveness (p<0.001) and airways obstruction (p = 0.011) occurred in children with atopic wheeze than in those with non-atopic wheeze at 10 years. Children with atopic wheeze more often received treatment (p<0.001) or an asthma diagnosis for their disorder, although current morbidity at 10 years differed little for these states. Maternal asthma and recurrent chest infections at 2 years were independently significant factors for developing non-atopic wheeze. For atopic wheeze, sibling asthma, eczema at 1 year, rhinitis at 4 years, and male sex were independently significant.

CONCLUSIONS

Non-atopic wheeze is as common as atopic wheeze in children aged 10 years, but treatment is more frequent in those with atopic wheeze. Different risk factor profiles appear relevant to the presence of atopic and non-atopic wheeze at 10 years of age.

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 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.

Evaluation of the effectiveness of pre-employment screening

AIM

As pre-employment screening and selection is a main function in the protection of susceptible applicants from developing an occupational disease, we need insight into the effectiveness of this intervention under different exposure conditions. The aim of our study was to demonstrate the feasibility and usefulness of three indicators to evaluate the effectiveness of pre-employment examinations.

METHOD

We used a pre-employment medical evaluation table to gather the data needed for the indicators for effectiveness. The first indicator chosen is the predictive value of a positive test result (PPV) corresponding to the percentage of applicants who will develop an occupational disease after a positive test result. The second indicator is the number of pre-employment medical examinations needed to reduce the number of new cases of an occupational disease by one (number needed to test, NNT). The third is the number of rejections for the job, as the consequence of a positive test result, needed to reduce the number of new cases of an occupational disease by one (number needed to reject, NNR). To illustrate feasibility and usefulness, we used the example of potroom asthma in the primary-aluminium industry. We used data on personal risk factors and on the incidence of potroom asthma from a nested case-control study in the Netherlands.

RESULTS

The three indicators for effectiveness could be applied. For high incidence rates, defined as 0.04 (40 cases/1000 employees per year), the PPV values for personal risk indicators varied from 5% to 27%. The NNT varied from 116 to 667. Finally, the NNR varied from 4 to 20. For low incidence rates, defined as 0.005 (5 cases/1000 employees per year), the PPV values were low (0.6% to 5%). The NNT were high (1111 to 5000). The NNR varied from 23 to 155.

CONCLUSION

The three indicators for effectiveness are applicable under the condition of the availability of relevant empirical data. The indicators provided useful information for the evaluation of the effectiveness of specific tests, which might be added as selection criteria. The personal risk factors studied were far from effective as selection instruments, especially in situations where a low incidence of potroom asthma exists. Personal risk factors at the pre-employment stage should not be added to the standard procedure to select susceptible applicants. Under conditions, they may be taken into account in a workers' health surveillance programme. As a contribution to evidence-based occupational medicine, we recommend the use of the pre-employment medical evaluation table and the three chosen indicators for effectiveness as a standard tool to evaluate the effectiveness of pre-employment medical examinations.

Effects of specific immunotherapy on the development of new sensitisations in monosensitised patients

BACKGROUND

Specific immunotherapy (SIT) is the only treatment that interferes with the basic pathophysiological mechanisms of allergic disease and is widely used in the management of clinically significant respiratory IgE-mediated diseases. Nevertheless, until recently, information on the influence of SIT on the development of new allergic sensitisations has been scant.

METHODS

One hundred consecutive patients (45 males and 55 females, aged 6 to 69 years) with respiratory allergic diseases and attending the allergy unit of a general hospital were selected. All had been diagnosed by clinical history and skin prick tests of allergic rhinitis and/or asthma, were monosensitised (71 to Dermatophagoides spp, 22 to Parietaria judaica pollen and 7 to grass pollen) and had been followed up as outpatients between 1990-98. Sixty-six patients had been treated with conventional SIT for at least 3 years, while thirty-four followed only environmental measures and drug treatment. Family atopy status (first-degree relatives), smoking, family pets (cat and/or dog), rhinitis and/or asthma symptom score and inhalant skin prick tests to the same aeroallergens were compared between baseline and after 3 to 5 years of treatment.

RESULTS

No statistically-significant differences in the development of new sensitisations were observed between the two groups (36.4 % of SIT-treated patients versus 38.2 % in control group, RR = 0.97, CI 95 %: 0.72-1.3). Smoking, family atopy history and pets did not appear to be risk factors for the development of neosensitisations (p < 0.05). Nevertheless, SIT-treated patients presented a better clinical score than the control group, with improvements of 89.4 % and 61.8 %, respectively (p = 0.007).

CONCLUSIONS

Three-year SIT did not protect against development of new sensitisations in monosensitised allergic rhinitis or asthma. Smoking, family atopy history and pets were not associated with development of new sensitisations. Clinical score improved significantly in the SIT-treated group compared with drug-treated patients.

Serum eosinophil cationic protein (S-ECP) in a population with low prevalence of atopy

The study is a part of the European Community Respiratory Health Survey. A random sample (n = 351) of 20-44-year olds and persons of the same age with asthma-like symptoms or current asthma medication according to a postal questionnaire (n = 95) were studied. Interview was taken, methacholine challenge was done and ECP, total and specific IgE were measured from serum. The median S-ECP value was 8.0 micrograms/l in the random sample. The geometric mean of S-ECP was higher in subjects with, than without atopy (10.2 vs 8.9 micrograms/l, P < 0.01) and in subjects with bronchial hyperresponsiveness (BHR) than in subjects without BHR (9.9 vs 8.0 micrograms/l, P < 0.01). The levels correlated weakly to forced expiratory volume in one second (FEV1) (r = 0.13, P < 0.01) and were not independently correlated with respiratory symptoms, asthma or FEV1 after adjusting for BHR, IgE, sensitisation and smoking. Our results indicate that the level of eosinophil activation is low in a population with a low prevalence of atopy, even when BHR is common.

Spirometric abnormalities associated with chronic bronchitis, asthma, and airway hyperresponsiveness among boilermaker construction workers

STUDY OBJECTIVES

In a 2-year longitudinal study of boilermaker construction workers, we found a significant association between working at oil-fired, coal-fired, and gas-fired industries during the past year and reduced lung function. In the present study, we investigated whether chronic bronchitis, asthma, or baseline methacholine airway responsiveness can explain the heterogeneity in lung function response to boilermaker work.

DESIGN

This study is part of an ongoing prospective cohort study of boilermakers. Exposure was assessed with a work history questionnaire. Spirometry was performed annually to assess lung function. A generalized estimating equation approach was used to account for the repeated-measures design.

SETTING

Boilermaker union members.

PARTICIPANTS

One hundred eighteen boilermakers participated in the study.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Self-reported history of chronic bronchitis and asthma were associated with a larger FEV1 reduction in response to workplace exposure at coal-fired and gas-fired industries. Although we found a high prevalence (39%) of airway hyperresponsiveness (provocative concentration of methacholine causing a 20% fall in FEV1 of < 8 mg/mL) among boilermakers, we did not find a consistent pattern of effect modification by airway responsiveness.

CONCLUSIONS

Although chronic bronchitis and asthma were associated with a greater loss in lung function in response to hours worked as a boilermaker, and therefore they acted as effect modifiers of the exposure-lung function relationship, airway hyperresponsiveness did not. However, the high prevalence of airway hyperresponsiveness found in the cohort may be a primary consequence of long-term workplace exposure among boilermakers.

Increase in the prevalence of allergen skin sensitization in successive birth cohorts

BACKGROUND

Little is known about longitudinal trends in the prevalence of allergen skin sensitization in the general population.

OBJECTIVE

We sought to measure the change in prevalence of allergen skin sensitization over a 9-year period in a cohort of adults and hence to determine whether cross-sectional differences in prevalence between age groups are due to an aging or cohort effect.

METHODS

In 1991 and 2000, we measured skin sensitization, defined as a wheal diameter of 3 mm or larger than that elicited by a saline control, to Dermatophagoides pteronyssinus, cat fur, mixed grass, Aspergillus fumigatus, and Cladosporium herbarum in a cohort of 1339 adults from Nottingham aged between 18 and 71 years in 1991. Subjects were divided into six 9-year successive birth cohorts, and the effects of birth cohort and the within-subject change from 1991 to 2000 were analyzed in a generalized estimating equation logit model.

RESULTS

The unadjusted prevalence of sensitization to any allergen was 30.5% in 1991 and 31.8% in 2000. In cross-sectional analyses the prevalence of sensitization decreased with increasing age at both surveys (risk ratio, 2.15; 95% confidence interval [CI], 1.45-3.17 for 18- to 26-year-old patients relative to 63- to 70-year-old patients in the 1991 survey). In longitudinal analysis there was no within-subject change in sensitization from 1991 to 2000 (adjusted odds ratio, 1.07; 95% CI, 0.97-1.19), but there was a significant cohort effect (adjusted odds ratio per successive 9 year cohort, 1.27; 95% CI, 1.18-1.37).

CONCLUSION

The cross-sectional decrease in allergen sensitization with age in the general population arises predominantly from a secular increase in sensitization prevalence with successive birth cohorts and not to a loss of sensitization within subjects over time. As a result of this cohort effect, the prevalence of allergic sensitization has increased in this general adult population sample.

Bronchial responsiveness to adenosine 5'-monophosphate (AMP) and methacholine differ in their relationship with airway allergy and baseline FEV(1)

Bronchial hyperresponsiveness (BHR) and inflammation are central hallmarks of asthma. Studies in patients with asthma suggest that BHR to adenosine 5'-monophosphate (AMP) is a better marker of bronchial inflammation than BHR to methacholine. The association between markers of airway inflammation and BHR to methacholine and AMP in a population of young adults, with mild symptoms if any, was evaluated. A total of 230 subjects who participated in a follow-up study on occupational allergy were included. Before exposure to occupational allergens, subjects completed a questionnaire on respiratory symptoms and were tested for atopy, blood eosinophilia (> or =275/mm(3)), and BHR to methacholine and AMP (> or =15% fall in FEV(1)). Risk estimates were expressed as prevalence ratios (PR) and 95% confidence intervals (95% CI). Dose-response slopes (DRS) for methacholine and AMP were compared between healthy control subjects, self-reported allergic rhinitis, and allergic asthma. BHR to AMP was associated with allergic rhinitis (PR 2.51, 95% CI: 1.22;5.17), allergic asthma (PR 4.38, 95% CI: 1.98;9.66), with atopy (PR 3.87, 95% CI: 1.76;8.52), and blood eosinophilia (PR 3.57, 95% CI: 1.48;8.77), but not with baseline FEV(1). BHR to methacholine was inversely related to prechallenge FEV(1) (PR 0.97, 95% CI: 0.96;0.99). For both methacholine and AMP the geometric mean DRS increased along the axis asymptomatic-allergic rhinitis-allergic asthma, but for AMP the increase was the strongest. In this population study among young adults, BHR to AMP refers to allergic background of airway lability and BHR to methacholine is related to a diminished airway caliber.

The association between persistent eosinophilia and asthma in childhood is independent of atopic status

BACKGROUND

Although peripheral blood eosinophilia is associated with risk of asthma, the relation with atopy has not been established.

OBJECTIVE

To assess the relationship between eosinophils and chronic asthma in childhood, and to determine the factors associated with eosinophil levels over time.

METHODS

Percent eosinophils/300 white blood cell (WBC) count ('eos') was measured at 9 months, 6 years and 11 years in subjects participating in the prospective Tucson Children's Respiratory Study. Children were classified based on the number of measurements in which they had low (< or = 2%) or high (>5%) eosinophils, as follows: (1) Persistently low eos (n = 130); (2) Low eos (intermittently low or consistently moderate, but never high, n = 317); (3) Intermittently high eos (n = 192); and (4) Persistently high eos (n = 17). Only children with > or = 2 eos measurements were included in the analysis. Chronic asthma was defined as medical doctor (MD)-diagnosed asthma with reports of wheezing during the previous year, on > or = 3 questionnaires completed between 2 and 13 years of age. Children with at least one positive skin prick test (SPT; > or = 3 mm) at age 6 or 11 were considered 'atopic'.

RESULTS

Chronic asthma was linearly related to longitudinally ascertained eosinophils (trend chi2 P<0.001) with prevalence ranging from 5.8% among children with persistently low eos to 37.5% among children with persistently high eos. This relation was independent of atopy. Parental history of asthma was associated with both chronic asthma (P <0.001) and with longitudinal eosinophil status (P < 0.001). After adjusting for atopy and gender, there was a 70% increase in asthma risk with each increase in longitudinal eosinophil level. This stepwise increase was reduced to 48% when parental asthma was added to the model.

CONCLUSION

Longitudinal eosinophil levels are linearly associated with chronic asthma in childhood, independent of atopy. The strong association between parental asthma and eosinophil status suggests that genetic background may be an important determinant of eosinophilic response.

Factors related to allergic sensitization to aeroallergens in a cross-sectional study in adults: The Copenhagen Allergy Study

BACKGROUND

The factors underlying recent increases in the prevalence of respiratory allergy are largely unknown.

OBJECTIVE

To assess the association between allergic sensitization and several lifestyle/environmental factors.

METHODS

A cross-sectional population-based study of 15-69-year-olds in Copenhagen was carried out in 1990. The participation rate was 77.5% (1112/1435). Different lifestyle/environmental factors (explanatory variables) were defined based on questionnaire data. Dependent (outcome) variables were skin prick test (SPT) positivity or specific IgE positivity to common aeroallergens. Explanatory variables associated with outcome in univariate analysis (P < 0.25) were selected for multivariate analysis. Subsequently, a final model for each dependent variable was obtained by stepwise regression analysis (cut-off for entry/removal of variables: P < 0.1).

RESULTS

Male sex, young age, low number of siblings, a positive family history of hay fever and never smoking, were independently associated with both SPT positivity and specific IgE positivity. Furthermore, SPT positivity was positively associated with alcohol consumption (dose-response relationship only), and negatively associated with previous keeping of a dog in the household. The association between alcohol consumption and SPT positivity was mainly due to the consumption of wine and remained after adjustment for educational level. Specific IgE positivity was furthermore associated with body mass index with no apparent dose-response relationship.

CONCLUSION

Being male, young age, a positive family history of hayfever, low number of siblings and never smoking, were independently associated with allergic sensitization. In addition, the results indicated a possible relationship of alcohol consumption, body mass index and previous keeping of a dog in the household to allergic sensitization. There is a need for prospective studies of risk factors for respiratory allergy.

Sensitization to common allergens and its association with allergic disorders at age 4 years: a whole population birth cohort study

BACKGROUND

Atopy is defined as the genetic propensity to develop immunoglobulin E antibodies in response to exposure to allergens and assessed by skin prick test responses to common allergens. Although it is generally agreed that atopy is an important risk factor for allergic diseases such as asthma, rhinitis, and eczema, the extent to which atopy accounts for these diseases is controversial.

OBJECTIVE

We aim to describe the prevalence of sensitization to common allergens and investigate the degree of association of atopy (as defined by positive skin prick test to 1 or more common allergens) to asthma, rhinitis, and eczema in a birth cohort at the age of 4 years.

METHODS

A birth cohort of 1456 children was recruited over a 14-month period (1989-1990). These children have been seen previously at 1 and 2 years of age. At 4 years, 1218 children were reviewed and an interview was administered or postal questionnaire was completed for the presence of allergic diseases (asthma, rhinitis, and eczema). Additionally, in 981 children, skin prick tests with a battery of 12 common allergens were performed. Allergens were house dust mite (Dermatophagoides pteronyssimus), grass pollen mix, cat, dog, Alternaria alternata, Cladosporium herbarum, cow's milk, hen's egg, soya, cod, wheat, and peanut. A mean wheal diameter of at least 3 mm greater than the negative control was taken as positive. This analysis is confined to the 981 (67% of the original population) who also had skin prick tests to the standard battery. chi(2) tests were used to test the univariate association between each allergic disease and positive skin test. Multiple logistic regression analysis was performed to obtain the adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the independent effect of sensitization to each allergen on allergic disease, adjusting for the effect of sensitization to other allergens. To ascertain how much of allergic disease is attributable to atopy, we estimated the population-attributable risk. This was calculated with the formula: P(R - 1) where R is the OR for the allergic disease under consideration and P is the proportion of atopy in children with that disease.

RESULTS

Children who were skin prick-tested at 4 years were similar in most characteristics to the rest of the population, except that they had a higher prevalence of allergic disease. Allergic disorders (asthma, rhinitis, and eczema) were present in 276 (28.1%) of 981. One hundred ninety-two (19.6%) children were atopic (positive reaction to 1 or more allergens). Sensitization to inhalant allergens was relatively common (19.2%) as compared with food allergens (3.5%). House dust mite (11.9%), grass pollen (7.8%), and cat (5.8%) were the most common positive reactions. A test to the 4 most common allergens (house dust mite, grass pollen, cat, and A alternata) could detect 94% of the atopic children. Sensitization to the 4 most common allergens was strongly associated with the presence of allergic disorders. There was a graded effect with the potent allergens, such as house dust mite, having the greatest impact. For example, 50% of children sensitized to house dust mite had asthma as opposed to 44% sensitized to cat, 42% sensitized to grass pollen, and 32% sensitized to A alternata. Overall, 68.4% of children sensitized to house dust mite had asthma, eczema, and/or rhinitis. The respective figures for grass pollen, cat, and A alternata were 64.9%, 66.7%, and 57.4%. The proportion of children sensitized to cat was not higher in households with cat ownership (households with cats: 5.1% [19/374]; households without cats: 6.2% [36/580]; not significant [NS]). Similarly, no difference was seen in sensitization to dog in households with and without dogs (households with dogs: 1.8% [5/282]; households without dogs: 2.8% [19/673]; NS). Boys were atopic more often than girls at this age (male: 112 of 497 [22.5%] vs female: 80 of 484 [16.5%]; OR: 1.47, 95% CI: 1.07-2.02). Male preponderance was observed with most allergens, but this was statistically significant only for house dust mite (male: 75/497 [15.1%] vs female: 42/484 [8.7%]; OR: 1.87; CI: 1.25-2.79) and grass pollen (male: 51/497 [10.3%] vs female: 26/484 [5.4%]; OR: 2.01; CI: 1.23-3.29). An independent effect of allergen sensitization on asthma was observed only with house dust mite with an OR of 8.07 (CI: 4.60-14.14). The highest independent risk for rhinitis was sensitization to grass pollen (OR: 5.02; CI: 2.21-11.41), and for eczema, sensitization to peanut (OR: 4.65; CI: 1.02-21.34). The majority of children (98/192) were sensitized to >1 allergen. A graded effect was observed with the risk of allergic disease in the child increasing with the number of positive skin prick test reactions. This effect was consistent throughout the spectrum of allergic diseases (asthma, eczema, and rhinitis). (ABSTRACT TRUNCATED)

Smoking and the development of allergic sensitization to aeroallergens in adults: a prospective population-based study. The Copenhagen Allergy Study

BACKGROUND

Several cross-sectional population-based studies have reported a negative association between smoking and allergic sensitization to aeroallergens. In a prospective study, we investigated the association between smoking and the development (incidence) of allergic sensitization as reflected by skin prick test (SPT) positivity and specific IgE positivity.

METHODS

Participants in a population-based study of 15 69-year-olds in 1990 were invited to a follow-up in 1998. Thus, SPT positivity and specific IgE positivity to common aeroallergens were assessed in 734 subjects (participation rate: 69.0%) on two occasions 8 years apart. The effect of smoking on the development of allergic sensitization was adjusted for potential confounders such as age, sex, family history of hay fever, educational level, and total IgE.

RESULTS

During the follow-up period, 58 and 33 subjects developed SPT positivity and specific IgE positivity, respectively. The risk of developing SPT positivity (adjusted odds ratio: 0.45, 95% CI 0.21-0.98) and specific IgE positivity (adjusted odds ratio: 0.62, 95%, CI 0.26-1.49) was lower among sustained smokers than never-smokers.

CONCLUSIONS

In this adult population, sustained smoking was negatively associated with the development of allergic sensitization to aeroallergens during an 8-year follow-up. This negative association, if real, might be due to an immunosuppressive effect of smoking.

Allergy markers in respiratory epidemiology

Assessing allergy by measurement of serum immunoglobulin (Ig) E antibodies is fast and safe to perform. Serum antibodies can preferably be assessed in patients with dermatitis and in those who regularly use antihistamines and other pharmacological agents that reduce skin sensitivity. Skin tests represent the easiest tool to obtain quick and reliable information for the diagnosis of respiratory allergic diseases. It is the technique more widely used, specific and reasonably sensitive for most applications as a marker of atopy. Measurement of serum IgE antibodies and skin-prick testing may give complimentary information and can be applied in clinical and epidemiological settings. Peripheral blood eosinophilia is less used, but is important in clinical practice to demonstrate the allergic aetiology of disease, to monitor its clinical course and to address the choice of therapy. In epidemiology, hypereosinophilia seems to reflect an inflammatory reaction in the airways, which may be linked to obstructive airflow limitation.

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.

Eosinophilia is associated with increased all-cause mortality after a follow-up of 30 years in a general population sample

We investigated whether allergy is associated with increased all-cause mortality. Two allergy markers, peripheral blood eosinophilia (> or =275 eosinophilic cells per mm3) and positive skin tests (sum score > or =3), were available for 5,383 subjects of a cohort study on asthma and chronic obstructive pulmonary disease in general population samples of Vlagtwedde and Vlaardingen, the Netherlands, in 1965-1972. During 30 years of follow-up, 1,135 subjects died. In a Cox regression analysis, eosinophilia was associated with an increased risk (relative risk = 1.4; 95% confidence interval = 1.2-1.7) of all-cause mortality, independent of gender, age, smoking habits, percentage predicted forced expiratory volume in 1 second (FEV1 % predicted), and positive skin tests at the start of the study. Subjects with positive skin tests had only an increased risk of all-cause mortality in the subgroup of subjects with FEV1 <80% of predicted (relative risk = 1.7; 95% confidence interval = 1.0-2.8). These results remained essentially unchanged after exclusion of subjects with asthma. We conclude that eosinophilia is associated with increased all-cause mortality. An increased number of peripheral blood eosinophils may reflect an increased inflammatory response, resulting in tissue injury. It is possible that the association between a low FEV1% predicted and all-cause mortality is partly mediated by an atopic constitution.

Induced sputum cell counts in healthy adults

Induced sputum cell counts provide a relatively noninvasive method to evaluate the presence, type, and degree of inflammation in the airways of the lungs. Their interpretation requires a knowledge of normal values from a healthy population. The objective was to examine the total and differential cell counts in induced sputum from a sample of healthy adults. A total of 118 healthy nonsmoking adults were studied. None had asthma or airflow obstruction (negative history, FEV(1) >/= 80% predicted, ratio of FEV(1) to vital capacity [FEV(1)/VC] >/= 80%, methacholine PC(20) >/= 16 mg/ml). Forty-six were atopic. Sputum induction produced an adequate sample in 96 subjects [53 males, mean age (range) 36 (18 to 60) yr]. The expectorate was processed within 2 h; sputum was selected, treated with dithiothreitol, filtered, and examined in a hemocytometer for total cell count and viability and on Wright-stained cytospins for a differential cell count. The mean, median (90th percentile) total cell count was 4.1, 2.4 (9.7) x 10(6) cells/g and cell viability was 69.6, 72.0 (89.7)%. The proportions of eosinophils were 0.4, 0.0 (1.1)%, neutrophils 37.5, 36.7 (64.0)%, macrophages 58.8, 60.8 (86.1)%, lymphocytes 1.0, 0.5 (2.6)%, metachromatic cells 0.0, 0.0 (0.04)%, and bronchial epithelial cells 1.6, 0.3 (4.4)%, respectively. Female gender and atopy were associated with a significant elevation of eosinophils; mean difference between male/female was 0.3% (p = 0.043) and between atopic/nonatopic 0.4% (p = 0.024). This study has identified reference values for total and differential cell counts in induced sputum of healthy adults.

Asthma attacks with eosinophilia predict mortality from chronic obstructive pulmonary disease in a general population sample

We studied the association between allergy defined as eosinophilia (>/= 275 cells/mm(3)) and/or positive skin tests (sum score >/= 3) and mortality from chronic obstructive pulmonary disease (COPD) after adjustment for major risk factors. In addition, we investigated this association in subgroups of respiratory symptoms and lung function. We used data from 7,556 participants of the respiratory surveys in 1964 -1972 in the general populations of Vlagtwedde, Vlaardingen, and Meppel (The Netherlands; mean age +/- SD: 39.3 yr +/- 14 in the 1960s). In 1995, the vital status was available (5,135 alive, 106 lost to follow-up, 121 primary deaths from COPD, and 2,194 other primary causes of which 137 had a secondary death cause from COPD. Positive skin tests were not associated with increased COPD mortality. The association between eosinophilia and COPD mortality was restricted to those who had reported asthma attacks and was present for both COPD as a primary cause (relative risk [RR] = 4.80; 95% confidence interval [CI] 1.9 to 11.9) and combined primary and secondary causes of death (RR = 3. 90; 95% CI 2.05 to 7.40). We conclude that eosinophilia with asthma attacks is a risk factor for COPD mortality in addition to known risk factors also found in our study such as male gender, older age, current smoking, low lung function, underweight, and dyspnea.

Smoking and airway hyperresponsiveness especially in the presence of blood eosinophilia increase the risk to develop respiratory symptoms: a 25-year follow-up study in the general adult population

Airway hyperresponsiveness (AHR) constitutes a risk for development of respiratory symptoms. We assessed whether blood eosinophilia (>/= 275 eosinophils/microliters), skin test positivity (sum score >/= 3) and cigarette smoking (never, ex-smoker, 1-14 cig/d, 15-24 cig/d, >/= 25 cig/d) at the first of two successive surveys are related to the development of respiratory symptoms (chronic cough or phlegm, bronchitis, persistent wheeze, dyspnea, and asthma) at the second survey, and whether these relations are the same in subjects with (PC10 </= 8 mg/ml histamine) and without AHR. We analyzed data of the longitudinal Vlagtwedde-Vlaardingen Study (1965 to 1990) using logistic regression analyses with paired observations, taking multiple measurements within a person into account. In total, 995 men and 792 women contributed 4,403 paired observations. Eosinophilia in hyperresponsive subjects significantly increased the risk to develop one or more respiratory symptoms (odds ratio [OR] = 3.67, 95% confidence interval [CI] = 1.79 to 7.52), wheeze (OR = 5. 06, 95% CI = 2.11 to 12.13), and dyspnea (OR = 2.73, 95% CI = 1.13 to 6.60), independent of smoking, age, sex, area of residence, and time between two successive surveys. Smoking at the first of two successive surveys increased the risk to develop symptoms in a dose-dependent relation. Subjects with positive skin tests in the past were less likely to develop one or more respiratory symptoms (OR = 0.64, 95% CI = 0.46 to 0.88) and chronic phlegm (OR = 0.65, 95% CI = 0.42 to 1.00), independent of AHR. This longitudinal study in the general adult population shows that cigarette smoking and hyperresponsive subjects are at increased risk to develop respiratory symptoms, and especially so when eosinophilia is present in hyperresponsive persons.

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.

[Relation between asthma and atopy markers in children and young adults]

The aim of this study was to assess whether atopy, measured as total IgE level (IgEt) and/or skin test (ST) reactivity is related to bronchial asthma in the same way in children and young adults. Three hundred fifty-three children between 11 and 15 years of age (mean 12.6 years) and 208 adults between 20 and 44 years old (mean 32.1 years) were selected randomly as representative of persons living in the city of Huelva (Spain). All subjects filled out a questionnaire on respiratory symptoms (The European Community Respiratory Health Survey--[ECRHS]) and were given a methacholine challenge test (MT) with results expressed as PD20 as well as IgEt and ST assessments of atopy. We defined bronchial asthma as the association of having experienced wheezing within the last 12 months and having a positive ST. Among children, 4.5% suffered bronchial asthma. Among adults the proportion was 5.3%. The IgEt value that best discriminated between asthmatics and non asthmatics was 145.5 U/ml in children (sensitivity 75% and specificity 69.1%) and 96.6 U/ml in adults (sensitivity 90.9% and specificity 73.6%). A logarithmic transformation (log IgEt) was used to study the relation between bronchial asthma and IgEt. By simple analysis, IgEt and ST were related to bronchial asthma in children (p = 0.002 and p < 0.0001, respectively), while only IgEt (p < 0.001) was related in adults. By multiple regression analysis, controlling for both factors simultaneously as well as for smoking in adults, we found that ST (p = 0.023) but not IgEt was related in children, whereas IgEt (p = 0.0005) but not ST was related in adults. We conclude that the two markers of atopy studied are related to bronchial asthma differently and have different manifestations at different stages of life. ST is more useful in children, whereas IgE determination is of more use in adults.

Skin prick test reactivity to common aeroallergens in relation to total IgE, respiratory symptoms, and smoking in a general population sample of northern Italy

Skin prick test (SPT) reactivity to common airborne allergens and its relationships to sex, age, smoking habits, and respiratory symptoms/diseases were evaluated in a general population sample (n = 2841, 8-75 years of age) living in the Po delta area (northern Italy). Subjects completed a standardized questionnaire and underwent prick tests (12 local allergens, a negative and a positive control) and determination of total serum IgE. Atopy was evaluated by measuring the maximal diameter for each allergen, after subtracting that of the negative control. Thirty-one percent of subjects showed a positive skin response at a 3-mm threshold. Pollens, Dermatophagoides pteronyssinus, and D. farinae caused the highest frequencies of reactions. Young people and those who had never smoked had higher prevalence rates of SPT reactivity. Asthma, asthma symptoms, and rhinitis were significantly associated with SPT reactivity in both sexes (cough only in females) and with the number of positive reactions. IgE values were also significantly associated with SPT reactivity. In conclusion, our findings indicate that almost one-third of the general population of an Italian rural area is skin test positive, emphasizing the importance of assessing atopy in respiratory epidemiologic surveys.

Adverse effects of eosinophilia and smoking on the natural history of newly diagnosed chronic bronchitis

BACKGROUND

Little is known about risk factors for the progression of disease in individuals with newly developed chronic bronchitis (CB). In addition to the effects of smoking, there was specific clinical and epidemiologic interest in the importance of traits such as eosinophilia and wheezing, more commonly associated with asthma, in the progression of this disease.

METHODS

We evaluated adult individuals with and without diagnosed CB longitudinally in a representative community population in Tucson, Ariz. These subjects were followed up for 13 years since 1972. Because we were interested in CB specifically, those with diagnoses of emphysema and asthma were removed from the data set. Initial level of FEV1 (%FEV1) and slopes in FEV1 were corrected for covariates and other important variables.

RESULTS

As expected, persistent and newly diagnosed CB was significantly more common in current and ex-smokers. Furthermore, initial lung function was lower, and decline in FEV1 was steeper in smokers with persistent and newly diagnosed CB. Newly diagnosed cases had steeper declines in FEV1 (-6.84 mL/yr below grand mean of -11.18 mL/yr) than normal subjects (+0.95 mL/yr). The incidence rate of newly diagnosed CB was significantly higher in those with eosinophilia (13.7%) than without eosinophilia (6.7%). Finally, new cases with eosinophilia had similar initial %FEV1 (95.4 +/- 1%) but much larger declines in function than new cases without eosinophilia: -24.5 versus -16.6 mL/yr. Adverse effects of wheeze were largely explained by smoking and eosinophilia.

CONCLUSION

Eosinophilia is an important aspect of CB in addition to smoking, and it should be considered in its evaluation. The presence of eosinophilia in newly diagnosed CB, with or without wheeze, may warn the clinician of the possibility of a rapid decline in FEV1.

Serum eosinophil cationic protein in relation to bronchial asthma in a young Swedish population

How are the serum concentration of eosinophil cationic protein (S-ECP) and the blood eosinophil count (B-Eos) related to symptoms of asthma, allergy, and bronchial hyperresponsiveness (BHR)? We measured S-ECP, B-Eos, and total and specific IgE in serum in blood samples from 699 randomly selected persons 20-44 years old. They also underwent a structured interview, spirometry, a methacholine provocation test, and skin prick tests as part of the European Community Respiratory Health Survey. B-Eos and S-ECP were found to be closely related to asthma symptom score (P < 0.001), total IgE (P < 0.001), and BHR (P < 0.001). On the basis of the results, the subjects were divided into four groups: healthy controls, patients with allergic rhinitis, patients with nonallergic asthma, and patients with allergic asthma. There were significant differences in both B-Eos and S-ECP among the groups (P < 0.001), the highest values being found in the allergic asthma group. B-Eos and S-ECP each had an additive value in predicting the occurrence of asthma. Among persons with high concentrations of both variables, asthma was eight times more common than in those with low concentrations. Allergy and BHR were also found to be independently related to B-Eos and S-ECP levels. Furthermore, both B-Eos and S-ECP showed good correlation to subjective and objective measures of asthma activity. We conclude that both B-Eos and S-ECP and their interrelationship may be of value in assessing the activity of asthma. However, their role in disease management was not established in this cross-sectional study.

Host factors and environmental determinants associated with skin test reactivity and eosinophilia in a community-based population study

We examined the relationship of host factors (age, gender) and environmental determinants (smoking status, area of residence) to indicators of allergy (skin test reactivity and eosinophil count) in a random population sample in the Netherlands. Positive skin test reactivity was associated with age (decreasing with increasing age), with male gender (versus female gender), and with urban residence (versus rural residence). Positive skin test reactivity was not associated with smoking. Elevated eosinophil counts were associated with male gender (versus female gender), with urban residence (versus rural residence), and with current smoking (versus never smoking). Elevated eosinophil counts were not clearly associated with age (if adjusted for the age-related effects of skin test reactivity). Additionally, this study specifically demonstrates that skin test reactivity increases with increasing eosinophil count and vice versa, indicating that the two traits are interrelated. Furthermore, this interrelationship was demonstrated to be age-dependent (decreasing with increasing age).

Allergen skin test reactivity in an unselected Danish population. The Glostrup Allergy Study, Denmark

The aim of this study was to assess the distribution of allergen skin test reactivity in an unselected Danish population. A total of 793 subjects, aged 15-69 years, were invited, and 599 (75.5%) attended. The skin prick test was performed with standardized allergen extracts of high potency. Skin reactivity occurred in 28.4% of the subjects. The frequency of skin reactivity to the specific allergens ranged from 1.5% (Cladosporium) to 12.5% (Dermatophagoides pteronyssinus), and the frequencies of skin reactivity to the allergen groups (pollen, animal dander, house-dust mites, and molds) were 17.6%, 8.7%, 14.0%, and 3.2%, respectively. Young women appeared to reflect the average skin reactivity. When compared with young women, skin reactivity to animal dander was more probable in young men (odds ratio (OR) value = 2.6; 95% confidence interval (CI) of odds ratio value = 1.1-6.1). Current smokers were less likely than nonsmokers to be skin-reactive to pollen (OR = 0.4; 95% CI = 0.3-0.7). In conclusion, allergen skin test reactivity was common, and was related to sex, age, smoking history, and probably genetic predisposition.

Prediction of respiratory symptoms by peripheral blood neutrophils and eosinophils in the First National Nutrition Examination Survey (NHANES I)

To examine specific cellular markers of inflammation in peripheral blood (neutrophils and eosinophils) and their relationship to respiratory symptoms, we used data from the First National Health and Nutrition Examination Survey (NHANES I). Cross-sectional data were available on a random sample of 6,913 adults aged 30 to 74 years who had American Thoracic Society-National Heart, Lung, and Blood Institute questionnaire information on respiratory symptoms and illnesses, including asthma, chronic bronchitis, dyspnea (grade 3), chronic cough, and chronic phlegm. Information was available on age, race, smoking status, peripheral blood leukocyte count, and differential cell count. These data were analyzed using logistic regression controlling for age, race, sex, and cigarette smoking. Physician-diagnosed asthma was significantly associated only with the eosinophil count (p = 0.001). Physician-diagnosed bronchitis was significantly associated with the neutrophil count (p = 0.012) and marginally associated with the eosinophil count (p = 0.072). Chronic phlegm was also significantly associated with both the eosinophil count (p = 0.049) and the neutrophil count (p = 0.041). Grade 3 dyspnea (p = 0.049) was only significantly associated with the neutrophil count. These data suggest that both peripheral blood neutrophils and eosinophils are associated with a broad range of respiratory symptoms and that the eosinophil may play a role in nonasthmatic respiratory inflammation.

Factors associated with bronchial responsiveness to histamine in a population sample of adults

The association of age, gender, number of eosinophils, area of residence, cigarette smoking, respiratory symptom prevalence, and FEV1 with the level of bronchial responsiveness was studied in a random sample of 2,216 subjects aged 15 to 72 yr. Subjects participated in the Dutch longitudinal study on chronic obstructive pulmonary disease. In 18 yr of follow-up, 5,012 observations were collected. Interviewers used a standardized questionnaire to assess the presence of respiratory symptoms. Bronchial responsiveness was measured by a histamine challenge test. Because multiple measurements within a subject are correlated, multivariate regression methods for correlated outcome were used. A greater number of eosinophils, skin test positivity, and living in a rural area (Vlagtwedde) were associated with increased responsiveness, independently of the level of FEV1 and the presence of respiratory symptoms. Older age was associated with increased responsiveness, and this was even more so in subjects with symptoms. Cigarette smokers were more responsive than nonsmokers, but this association was not significant if the level of FEV1 was taken into account. Hyperresponsiveness was more likely to be present if the amount of cigarettes smoked per day was greater. The level of responsiveness did not differ significantly between males and females. For the same degree of obstruction, however, expressed as the FEV1/VC ratio, males tended to be less responsive than females. The analyses were repeated using the dose-response slope as a continuous measure of responsiveness and by applying a method to adjust for censoring the responsiveness data. These analyses yielded identical results.

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.