EAACI Position Paper on assessment of cough in the workplace

Cough is a nonspecific and relatively common symptom that can present difficulties in diagnosis and management, particularly when it is reported to be associated with the workplace. The present consensus document, prepared by a taskforce of the Interest Group on Occupational Allergy of the European Academy of Allergy and Clinical Immunology by means of a nonsystematic review of the current literature, is intended to provide a definition and classification of work-related chronic cough (WRCC) to assist the daily practice of physicians facing with this symptom. The review demonstrates that several upper and lower airway work-related diseases may present with chronic cough; hence, the possible link with the workplace should always be considered. Due to the broad spectrum of underlying diseases, a multidisciplinary approach is necessary to achieve a definite diagnosis. Nevertheless, more epidemiological studies are necessary to estimate the real prevalence and risk factors for WRCC, the role of exposure to environmental and occupational sensitizers and irritants in its pathogenesis and the interaction with both upper and lower airways. Finally, the best management option should be evaluated in order to achieve the best outcome without adverse social and financial consequences for the worker.

Development and implementation of guidelines in allergic rhinitis – an ARIA-GA2LEN paper

The links between asthma and rhinitis are well characterized. The Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines stress the importance of these links and provide guidance for their prevention and treatment. Despite effective treatments being available, too few patients receive appropriate medical care for both diseases. Most patients with rhinitis and asthma consult primary care physicians and therefore these physicians are encouraged to understand and use ARIA guidelines. Patients should also be informed about these guidelines to raise their awareness of optimal care and increase control of the two related diseases. To apply these guidelines, clinicians and patients need to understand how and why the recommendations were made. The goal of the ARIA guidelines is to provide recommendations about the best management options for most patients in most situations. These recommendations should be based on the best available evidence. Making recommendations requires the assessment of the quality of available evidence, deciding on the balance between benefits and downsides, consideration of patients’ values and preferences, and, if applicable, resource implications. Guidelines must be updated as new management options become available or important new evidence emerges. Transparent reporting of guidelines facilitates understanding and acceptance, but implementation strategies need to be improved.

Occupational rhinitis

The present document is the result of a consensus reached by a panel of experts from European and nonEuropean countries on Occupational Rhinitis (OR), a disease of emerging relevance, which has received little attention in comparison to occupational asthma. The document covers the main items of OR including epidemiology, diagnosis, management, socio-economic impact, preventive strategies and medicolegal issues. An operational definition and classification of OR tailored to that of occupational asthma, as well as a diagnostic algorithm based on steps allowing different levels of diagnostic evidence, are proposed. The needs for future research are pointed out. Key messages are issued for each item.

[Sensitization to Aspergillus fumigatus and functional outcome of asthma]

INTRODUCTION

Despite a high prevalence in the asthmatic population, sensitization to Aspergillus has not benefited from the same research interest as the other mould species. This study aims at investigating the role of the presence or the absence of Aspergillus sensitization in the deterioration of airway caliber in asthmatics over a five-year follow-up.

MATERIAL AND METHODS

One hundred and thirty-three asthmatic subjects aged 18 to 40 years were separated into two groups: those sensitized (cases) and those not sensitized (controls) to Aspergillus were matched according to the following criteria: age, gender and FEV1 (% pred). Clinical, functional, allergic and therapeutic parameters were studied.

RESULTS

The FEV1 slope was less pronounced in the group sensitized to Aspergillus (-17 mL/year) in comparison to the controls (27 mL/year). There was also a less noticeable slope of forced vital capacity in the sensitized subjects (-25 mL/year) as compared to the controls (28 mL/year). All of these differences were not statistically significant.

CONCLUSION

We did not find any increase in the decline in FEV1 or FVC associated with sensitization to Aspergillus.

Exaggerated bronchoconstriction due to inhalation challenges with occupational agents

Inhalation challenges with occupational agents are used to confirm the aetiology of occupational asthma. It has been proposed that using closed-circuit equipment rather than the realistic challenge method would improve the methodology of these tests. Changes in forced expiratory volume in one second (FEV1) were examined in 496 subjects with "positive specific inhalation challenges", i.e. changes in FEVI of > or = 20% after exposure to an occupational agent, including 357 subjects exposed by the realistic method, 108 using the closed-circuit method and 31 by both methods. For immediate reactions, 18 of 95 (19%) showed changes in FEV1 of > or = 30% with the closed-circuit method, whereas a significantly larger proportion, i.e. 77 of 200 (38.5%), showed such changes using the realistic method. As regards nonimmediate reactions, changes in FEV1 of > or = 30% occurred in 16 of 43 (37%) cases with the closed-circuit method as compared to a larger proportion, i.e. 87 of 180 (48%) cases, using the realistic method. This favourable effect was significantly more pronounced in workers with higher levels of bronchial hyperresponsiveness to methacholine. It is concluded that, for agents that can be generated using the closed-circuit method, use of such apparatus results in a smaller proportion of exaggerated bronchoconstriction than does the realistic method, this being particularly true for low-molecular weight agents.

Controversies in epidemiology of occupational asthma

Epidemiology is the study of the distribution, determinants and outcome of disease. In this article, the recently acquired knowledge of the epidemiology of occupational asthma is described, as well as current areas of controversy. Incidence figures obtained from field studies in high-risk workplaces, medicolegal statistics and sentinel programmes indicate that approximately 10% of adult-onset asthma is attributable to the workplace. The strategy to identify cases through questionnaires and tools that address functional, immunological and physiopathological issues needs to be improved. Although few in number and limited to a handful of workplaces, cohort studies found that the risk of developing occupational asthma is determined less by individual susceptibility (e.g. atopy, tobacco smoking, human leukocyte antigen phenotype) and more by the level of exposure to its causes; in general, the higher the exposure, the greater the risk, and, by implication, lowering the level of exposure reduces the incidence of disease. Occupational asthma can be used as a satisfactory model for the development of adult-onset asthma. There is a great need to develop intervention strategies through adequate surveillance programmes in high-risk workplaces.

Incidence of probable occupational asthma and changes in airway calibre and responsiveness in apprentice welders

The majority of cross-sectional studies have shown a higher prevalence of ventilatory impairment in welders while only few longitudinal studies were able to detect chronic effects on spirometry or bronchial responsiveness. The aim of the study was to determine the incidence of probable occupational asthma (OA), bronchial obstruction and hyperresponsiveness among 286 students entering an apprenticeship programme in the welding profession. This epidemiological prospective cohort study consisted of a baseline assessment survey and two follow-up assessments. A respiratory symptom questionnaire was administered at each visit. Spirometry and methacholine bronchial challenge test results, conducted once prior to onset of exposure and later after an average of 15 months of apprenticeship, were available for 194 subjects. The incidence of probable OA was approximately 3% (6 of 194). The incidence of bronchial hyperresponsiveness, defined as a > or = 3.2-fold decrease in the provocative concentration causing a 20% fall in the forced expiratory volume in one second from baseline to the end of the study was 11.9%. A statistically significant difference was found between the baseline and end of study for the lung function values. In particular, the forced expiratory volume per cent predicted had significantly dropped by 8.4% on average. The significance of these early pulmonary function changes in relation to possible chronic effects of exposure to welding fumes and gases remains to be explored.

Diagnosing occupational asthma: how, how much, how far?

Diagnosing occupational asthma is still a challenge because it is based on a stepwise approach in which the depth of investigative means may vary depending on resources. The authors herewith review the existing investigative means from the approach of outlining controversies and queries. There is no validated clinical questionnaire for diagnosing occupational asthma. Immunological investigation is limited by the lack of standardised extracts for skin-prick testing and specific immunoglobulin E assessments. Criteria for interpretation of changes in peak expiratory flow rates and bronchial responsiveness to pharmacological agents are still open to discussion. It is worth improving the methodology of specific inhalation challenges, either in the laboratory or in the workplace, to facilitate more extensive use of these tests. Validation of new means that assess airway inflammation, such as exhaled nitric oxide and induced sputum, needs to be performed. There is a need to increase the use of these diagnostic tests because the diagnosis is still too often based on "clinical impression".

Definitions and types of work-related asthma: a nosological approach

The workplace can trigger or induce asthma and cause the onset of different types of work-related asthma. Analysis of previous definitions of occupational asthma (OA) led to the conclusion that evidence of a direct causal relationship between workplace exposure and the development of asthma remains the key element for defining OA. Based on clinical features and pathophysiological mechanisms, the following conditions should be distinguished in the spectrum of work-related asthma: 1) immunological OA characterised by a latency period necessary to acquire immunologically induced sensitisation; 2) nonimmunological OA characterised by the rapid onset of asthma following single or multiple exposures to high concentrations of irritant compounds; 3) work-related asthma defined by exacerbation of symptoms in workers with pre-existing or coincident asthma; and 4) variant syndromes including eosinophilic bronchitis, potroom asthma, and asthma-like disorders caused by organic dusts. The issues and controversies relating to this approach are critically reviewed in order to stimulate the consensus development of operational definitions of work-related asthma.

Assessment and evaluation of symptomatic steroid-naive asthmatics without sputum eosinophilia and their response to inhaled corticosteroids

Eosinophilic airway inflammation is one of the hallmarks of asthma. Sputum eosinophilia has been suggested as a predictor of the response to inhaled corticosteroids in asthma. This study sought to investigate the proportion of steroid-naive uncontrolled asthmatics without significant sputum eosinophilia (< or = 1%) and to examine whether sputum eosinophilia could predict the response to inhaled corticosteroids. A total of 51 mild uncontrolled steroid-naive asthmatics who had not been treated with oral or inhaled corticosteroids for at least 3 months were investigated. The evaluation included a spirometry, methacholine inhalation challenge and sputum induction on two occasions, one at baseline and the other after 1 month of treatment with 250 microg twice-daily fluticasone propionate. Of the 51 subjects, 15 had an eosinophil count < or = 1%, and 46 completed the two visits. Patients with baseline sputum eosinophils < or = 1% (n=14) were compared with those with sputum eosinophils > 1% (n=32). The baseline characteristics of these two groups were similar. After 1 month of treatment, respiratory symptoms, quality of life, forced expiratory volume in one second (FEV1) and provocative concentration causing a 20% fall in FEV1 improved in both groups. The absence of sputum eosinophilia does not seem to be an indicator of poor response to inhaled corticosteroid treatment in steroid-naive asthmatics. However, this finding needs to be investigated further in a double-blind, placebo-controlled study, entirely designed to answer this question.

Exposure to formaldehyde among animal health students

The objective of the present study was to evaluate the exposure to formaldehyde in 2 groups each with 18 students in animal health technology from two different training centers (TC) during a 3-hour weekly laboratory session in biology. Personal sampling during the session was done with passive bubblers for formaldehyde. The analysis of formaldehyde was done by visible absorption spectrometry according to NIOSH method 3500. The students in TC 1 were exposed to formaldehyde levels ranging from less than 0.11 to 0.76 mg/m3 with an average at 0.25 mg/m3 during the 3-hour biology laboratory. The students in TC 2 were exposed to higher concentrations of formaldehyde ranging from 0.26 to 1.2 mg/m3 with an average at 0.632 mg/m3. The results of the survey indicate that the students in both centers were exposed to a notable amount of formaldehyde vapor, at a level that is above the threshold limit value.

Host determinants for the development of allergy in apprentices exposed to laboratory animals

The aim of this study was to evaluate whether determinants of work-related symptoms, skin sensitization and diseases differ between atopic and nonatopic subjects starting a career with exposure to laboratory animals (LA). A cohort of 417 apprentices in animal-health technology was prospectively followed during 32 or 44 months. The effect on the study outcomes of variables derived from questionnaire, skin reactivity, and lung function assessments at baseline were compared in atopic (n=212) and nonatopic (n=183) subjects. Eighty-five incident cases of sensitization to a LA-derived allergen were identified, 67 among atopic and 18 among nonatopic subjects. Baseline rhinitis symptoms in contact with pets and skin sensitization to pets were associated with the development of work-related rhinoconjunctivitis (RC) symptoms in atopic subjects, whereas perannual rhinitis symptoms and having a PC20 (provocative concentration causing a 20% fall in forced expiratory volume in one second) < or = 32 mg x mL(-1) were associated in nonatopic subjects. Baseline rhinitis symptoms on contact with pets and a PC20 value < or = 32 mg x mL(-1) were significant determinants for developing sensitization to a specific allergen in atopic subjects only. Finally, baseline rhinitis symptoms in contact with pets and perannual rhinitis symptoms were associated with the development of occupational RC in atopic subjects, whereas in nonatopic subjects this was associated with having a PC20 value < or = 32 mg x mL(-1). In conclusion, the determinants for the development of specific skin sensitization, symptoms and disease are different between atopic and nonatopic apprentices starting occupational exposure to laboratory-animal-derived allergens.

Occupational asthma

The workplace can be responsible for approximately one in 10 cases of adult-onset asthma. Two types of occupational asthma (OA) are distinguished by whether they arise after a latency period that is necessary for acquiring sensitization or as a result of acute exposure to irritant materials (irritant-induced asthma). The pathophysiology of OA with a latency period is similar to that of nonoccupational asthma, whereas the mechanism of irritant-induced asthma is still uncertain. HLA haplotypes and other genetic polymorphisms have been found to be associated with OA. According to various sources of data, the overall frequency of OA has remained stable in the last 10 years, although the frequency of causal agents vary. Registers of causal occupations and agents have been issued on Web sites (eg, www.asmanet.com ). Improved sampling methods have shown that the degree of exposure plays a key role in the onset of the disease, whereas prospective data collected in high-risk workplaces have also identified personal risk factors (eg, atopy, smoking, and rhinoconjunctivitis). A diagnosis of OA should no longer be based on a compatible history only but should be confirmed by means of objective testing. Once the diagnosis is confirmed, the worker should be removed from exposure, and satisfactory compensation programs should be offered, the most important being retraining programs with financial compensations because affected workers are generally young. The cost-effectiveness of prevention programs in high-risk workforces should be assessed.

Changes in sputum cell counts after exposure to occupational agents: what do they mean?

BACKGROUND

Exposure to occupational agents can induce eosinophilic inflammation in subjects with occupational asthma (OA). It might also induce nonspecific changes in airway inflammation in subjects without OA.

OBJECTIVES

We sought to investigate the changes in airway inflammation induced by exposure to occupational agents in subjects with and without OA and to determine which changes in sputum eosinophil numbers and bronchial responsiveness to methacholine should be regarded as clinically significant for predicting a 20% fall in FEV(1).

METHODS

We performed specific inhalation challenges (SICs) in 3 groups of subjects: subjects reporting a history consistent with OA with a positive SIC response (n = 17); subjects reporting a history consistent with OA with a negative SIC response (n = 14); and asthmatic subjects without any history of OA (n = 10). Induced sputum and methacholine challenges were performed at the end of the control day and again at the end of the last day of exposure; the last day of exposure was always performed in the laboratory.

RESULTS

There was an increase in median sputum eosinophil and neutrophil numbers in subjects with positive SIC responses. Cell counts remained unchanged after exposure in asthmatic subjects without OA. A combination of a greater than 0.26 10(6)/mL increase in sputum eosinophil numbers and a decrease in the concentration of methacholine inducing a 20% fall in FEV(1) of at least 1.8-fold compared with baseline values predicted a 20% fall in FEV(1) in 96% (95% CI, 70%-99%) of patients.

CONCLUSION

Exposure to occupational agents per se does not induce airway inflammation. Changes in both sputum eosinophil counts and methacholine responsiveness are satisfactory predictors of a significant bronchial responsiveness to occupational agents.

Natural history of sensitization, symptoms and occupational diseases in apprentices exposed to laboratory animals

The natural history of the development of sensitization and disease due to high-molecular-weight allergens is not well characterized. This study describes the time-course of the incidence of work-related symptoms, skin reactivity and occupational rhinoconjunctivitis (RC) and asthma (OA); and assesses the predictive value of skin testing and RC symptoms in apprentices exposed to laboratory animals, in a 3-4-yr programme. Four-hundred and seventeen apprentices at five institutions were assessed prospectively with questionnaire, skin-testing with animal-derived allergens, spirometry and airway responsiveness (n=373). Depending on the school, students were seen 8 (n=136), 20 (n=345), 32 (n=355) and 44 (n=98) months after starting the programme. At all visits, the incidence was greater for work-related RC symptoms followed in order by skin reactivity, occupational RC, and, almost equally, OA and work-related respiratory symptoms. The incidence-density figures were comparable for each follow-up period and for most indices up to 32 months after entry into the study and then tended to decrease. The positive predictive values (PPVs) of skin reactivity to work-related allergens for the development of work-related RC and respiratory symptoms were 30% and 9.0%, respectively, while the PPVs of work-related RC for the development of OA was 11.4%. Sensitization, symptoms and diseases occur maximally in the first 2-3 yrs after starting exposure to laboratory animals. Skin reactivity to work-related allergens and rhinoconjuctivitis symptoms have low positive predictive values.

Incidence of sensitization, symptoms, and probable occupational rhinoconjunctivitis and asthma in apprentices starting exposure to latex

Latex is a well-known sensitizer. Prospective studies in apprentices beginning to be exposed to latex have not been carried out. We wanted to determine the incidence of skin reactivity, cutaneous symptoms, rhinoconjunctivitis (RC) symptoms, respiratory symptoms, probable occupational RC, and asthma in apprentices in dental hygiene. A total of 122 students starting a program in dental hygiene technology were recruited between 1993 and 1995. A questionnaire, skin-prick tests with common aeroallergens and latex, and assessment of spirometry and responsiveness to methacholine were carried out on entry and at follow-up visits at 20 and 32 months after the start of exposure. Of the 110 subjects who participated for at least 1 follow-up visit, skin reactivity to latex developed in 7. Cutaneous symptoms developed in 6 of the 7, RC symptoms developed in 2, and respiratory symptoms developed in 1. Five of the 7 subjects had significant changes in methacholine responsiveness and fulfilled the definition of probable occupational asthma. Sensitized subjects were more likely to be atopic and to have a previous history of asthma and respiratory symptoms on exercise than were nonsensitized subjects. Three subjects at the 20-month assessment and 4 subjects at the 32-month visit showed skin reactivity. The cumulative incidences for skin sensitization, probable occupational RC, and occupational asthma to latex were 6.4%, 1.8%, and 4.5%, respectively.

Family size, day-care attendance, and breastfeeding in relation to the incidence of childhood asthma

A hypothesis has been suggested stating that children exposed early to infections are less likely to develop atopy or asthma. The authors investigated the relation between risk of childhood asthma and number of siblings as well as day-care attendance, as factors possibly increasing the likelihood of early infections, and breastfeeding as a factor reducing them. A case-control study was carried out in Montréal, Canada, between 1988 and 1995 that included 457 children diagnosed with asthma at 3--4 years of age and 457 healthy controls. Cases followed for 6 years were later classified as persistent or transient by the symptoms and use of medication after diagnosis. Among cases diagnosed at 3--4 years of age, the adjusted odds ratio for asthma was 0.54 (95% confidence interval (CI): 0.36, 0.80) for one sibling and 0.49 (95% CI: 0.30, 0.81) for two or more. The adjusted odds ratio for day-care attendance before 1 year of age was 0.59 (95% CI: 0.40, 0.87). Results were similar with persistent cases. Among transient cases (who possibly had an infection with wheezing at 3--4 years of age), day-care attendance and a short duration of breastfeeding resulted in increased risk. The results support the hypothesis that opportunity for early infections reduces the risk of asthma.

Incidence and host determinants of probable occupational asthma in apprentices exposed to laboratory animals

Laboratory animal (LA) workers are frequently affected with allergic sensitization and occupational asthma (OA). The role of preexposure host factors, in particular airway responsiveness, on the incidence of OA has not been satisfactorily studied. A prospective cohort study of 417 apprentices in animal-health technology was conducted to investigate the incidence and determinants of probable OA. Questionnaire and skin-prick tests with common and work-specific allergens were administered on entry and at follow-up visits (up to three) from 8 to 44 mo after starting apprenticeship. Responsiveness to inhaled methacholine was assessed at baseline and at follow-up in apprentices who developed a new specific skin sensitization and in control subjects. Preexposure host characteristics and the school attended were compared between cases and all cohort subjects not meeting the criteria for probable OA. Twenty-eight apprentices satisfied the definition for probable OA, i.e., onset of immediate skin reactivity to > 1 occupational inhalant and > 3.2-fold decrease in the provocative concentration causing a 20% reduction in FEV(1) (PC(20)). The incidence of probable OA was 2.7% (28/1,043 person-years). Baseline immediate skin reactivity to pets (rate ratio [RR] 4.1, 95% confidence interval [CI] = 1.6 to 10.8), and bronchial responsiveness (PC(20) < or = 32 versus PC(20) > 32 mg/ ml) (RR = 2.5, 95% CI = 1.0 to 5.8) were associated with an increased risk of probable OA; a lower FEV(1) had an apparent, protective effect (RR = 0.58, 95% CI = 0.43 to 0.78). It is concluded that apprentices in animal health show a high incidence of probable OA, and that preexposure airway caliber and responsiveness as well as sensitization to pets are associated with an increased risk.

Incidence and determinants of IgE-mediated sensitization in apprentices. A prospective study

We investigated prospectively the incidence and determinants of work-related specific skin sensitization in a cohort of 769 apprentices, including 417 in animal health technology, 230 in pastry-making, and 122 in dental-hygiene technology. Subjects were recruited when starting exposure to laboratory animals, flour, or latex. A questionnaire and skin-prick tests with common and work-related allergens were administered on entry and at follow-up visits from 8 to 44 mo; information on number of hours of exposure to specific allergens was obtained. Among 769 apprentices, 698 attended >/= 1 follow-up visit. A total of 111 subjects developed specific sensitization over the study period. The incidence of work-related sensitization (per person-year) was 8.9% (95% CI 7.3 to 11.0%) in the animal-health program, 4.2% (95% CI 1.8 to 8.2%) in the pastry-making program, and 2.5% (95% CI = 0.7 to 4.3%) in the dental-hygiene program. In the animal health group, Cox regression analyses showed that atopy, nasal, and respiratory symptoms in the pollen season, and exposure assessed by the school attended or by duration of exposure to rodents were the most significant predictors of sensitization. In the dental-hygiene program, atopy and asthma were significant determinants. This study shows that: (1) an apprenticeship in animal-health technology carries a greater risk of developing specific sensitization than do apprenticeships in pastry-making and dental-hygiene; (2) atopy, respiratory symptoms in the pollen season, and number of hours in contact with rodents determine the risk of sensitization in apprentices in the animal health program.

What is the respiratory retention of inhaled hexamethylene di-isocyanate?

Isocyanates are a frequent cause of occupational asthma. Specific inhalation challenges are often required to confirm the diagnosis. The inhaled concentration has to be assessed during this procedure. However, the respiratory retention of di-isocyanate has not, to the authors knowledge, been evaluated in humans. The existence of a closed-circuit apparatus, designed to carry out these challenges, makes it possible to assess the dose. The respiratory retention of hexamethylene di-isocyanate (HDI) generated in vapour form, in both normal subjects (n=4) and subjects referred for the investigation of occupational asthma due to HDI in whom the diagnosis was excluded (n=5), was assessed. The latter group included four subjects with nonoccupational asthma. The HDI was generated at concentrations varying 5.1-15.2 ppb. The expired concentrations of HDI during such challenges varied 1.4-5.3 ppb. Therefore, the respiratory retention was 61-90%. To conclude, the majority of inhaled hexamethylene di-isocyanate vapour is retained within the airways and/on lung parenchyma.

Persistent specific bronchial reactivity to occupational agents in workers with normal nonspecific bronchial reactivity

Specific bronchial reactivity (SBR) to common inhalants is related to the degree of nonspecific bronchial reactivity (NSBR) and to specific allergen sensitivity. We investigated 16 workers with normal NSBR who had been previously diagnosed with occupational asthma caused by high-molecular-weight agents. The agents were flour in seven workers, psyllium in five, and guar gum in four. The subjects had been removed from exposure to these agents for a mean of 5.7 (+/- 4.0 SD) yr, no longer showed evidence of persisting asthma, and had a normal lung function. In the present study, the workers were reexposed to the sensitizing agent by specific inhalation challenges, in the same way they were as at the time of the diagnosis, to assess their current SBR to the sensitizer. SBR was estimated as the duration of exposure that induced a 20% decrease in FEV(1). Eleven of the 16 subjects had an asthmatic reaction at the time of the study; the duration of exposure necessary to induce the asthmatic reaction was the same as that needed at the time of diagnosis (3.55 +/- 0.5 min and 4.2 +/- 0.7 min, respectively, p = 0.8). The decrease in specific IgE levels between the two events was much greater in the subjects who failed to react to the second challenge test (from 24.2 +/- 37.5% to 3.0 +/- 16.9% binding) than in those who reacted on both occasions (from 31.2 +/- 27.0% to 21.6 +/- 36.7% binding); however, in both groups the change was significant (p = 0.05 and 0.04, respectively). We conclude that SBR to high-molecular-weight agents persists in most cases despite a normalization of NSBR, and that this persistence is associated with a persistence of specific immunization to the agent.

Influence of asthma education on asthma severity, quality of life and environmental control

BACKGROUND

Several studies have examined the influence of asthma education, focusing mainly on the use of health services.

OBJECTIVES

To assess the influence of an asthma education program (AEP) on airway responsiveness, asthma symptoms, patient quality of life (QOL) and environmental control.

DESIGN

A prospective, randomized, controlled study with parallel groups.

SETTING

Three tertiary care hospitals in Quebec.

POPULATION

One hundred and eighty-eight patients with moderate to severe asthma.

INTERVENTION

After optimization of asthma treatment with inhaled corticosteroids, patients were randomly assigned to receive either an education program based on self-management (group E) or usual care (control group C).

RESULTS

One year after an AEP, there was a significant decrease in the number of days per month without daytime asthma symptoms in group E only (P=0.03). Asthma daily symptom scores decreased significantly in group E in comparison with group C (P=0. 006). QOL scores improved markedly in both groups after treatment optimization during the run-in period (P<0.01). After an AEP, the QOL score increased further in group E patients in comparison with group C patients (P=0.04). The concentration of methacholine that induces a 20% fall in forced expiratory volume in 1 s (PC20) improved significantly in both groups (group E 1.2+/-1.1 to 2.4+/-0. 2, group C 1.5+/-1.2 to 2.4+/-1.3, P<0.01). After one year, 26 of 37 patients from group E sensitized to house dust mites (HDM) adopted the specific measures recommended to reduce their exposure to HDM, while none of the 21 subjects from group C did (P<0.001). Among the patients sensitized to cats or dogs, 15% of patients from group E and 23% of patients in group C no longer had a pet at home at the final visit (P>0.5).

CONCLUSIONS

One year after the educational intervention, it was observed that the program had added value over and above that of optimization of medication and regular clinical follow-ups. The education program was highly effective in promoting HDM avoidance measures but minimally effective for removing domestic animals, suggesting that more efficient strategies need to be developed for the latter.

Occurrence and risk factors of oral candidiasis treated with oral antifungals in seniors using inhaled steroids

Oral candidiasis (OC) is a frequent side effect of inhaled corticosteroids (iCSTs). This study estimated occurrence and significance of risk factors of OC treated with antifungals in users of iCSTs under conditions of normal use. This retrospective analysis used data drawn from drug insurance plan records in Quebec, Canada. The sample contained 27,000 seniors using anti-asthma medications during 1990. Three years of data (1989-1991) were searched for use of oral antifungals concurrent with exposure to iCSTs. A case-control study examined factors leading to increased probability of first incidence of OC in new users of iCSTs. Three-year occurrence for OC was 7%. Increased risk for a first occurrence of OC was significantly associated with higher doses of iCST, increased length of iCST exposure, use of antibiotics, use of oral steroids, having three or more prescribers, a history of use of both high and low strengths of iCST, and concurrent use of oral steroids and diabetes medications. The occurrence of OC is relatively high. Knowledge of factors leading to increased risk could facilitate the targetting of patients who need timely intervention, under conditions of normal use.

Frequency and determinants of exaggerated bronchoconstriction during shortened methacholine challenge tests in epidemiological and clinical set-ups

The European Respiratory Society guidelines on bronchial provocation testing have proposed time-saving procedures, which may lead to unwanted exaggerated responses. The frequency and determinants of exaggerated bronchoconstriction in response to methacholine inhalation testing in clinical and epidemiological settings have not been assessed. The authors evaluated: 1) the prevalence of exaggerated bronchoconstriction, 2) its relation to time-saving measures (starting methacholine concentration and skipping concentrations); and 3) associations between such reactions and risk factors, respiratory symptoms and/or lung function parameters. Clinical (n=408) and epidemiological (n=711) groups were included. Exaggerated bronchoconstriction was defined as either a fall > or =20% following saline or a > or =30% fall in forced expiratory volume in one second (FEV1) after methacholine inhalations. Cases were compared with two groups of subjects: 1) with measurable bronchial responsiveness (MBR); and 2) without MBR. In the epidemiological group, 84 subjects (12%) presented exaggerated bronchoconstriction. Skipped concentrations accounted for an exaggerated bronchoconstriction in 18 of these. In the clinical group, 41 subjects (10%) experienced exaggerated reactions. Skipped concentrations accounted for an exaggerated bronchoconstriction in five of these. The provocative concentration of methacholine causing a 20% fall in FEV1 values were marginally lower in subjects with exaggerated bronchoconstriction. Questionnaire analysis in epidemiological subjects showed some symptoms of asthma and rhinitis to be more prevalent in cases than in subjects without MBR. In conclusion, methacholine inhalation tests with time-saving measures result in a 10% risk of exaggerated bronchoconstriction as defined in this study and bronchial responsiveness is more prominent in subjects with exaggerated bronchoconstriction.

Individual characteristics and quitting in apprentices exposed to high-molecular-weight agents

To determine whether specific immunological sensitization (SIS) and symptoms of allergy are associated with quitting apprenticeships with exposure to high-molecular-weight (HMW) agents. In a cohort study of 769 apprentices starting career programs in animal health technology (AHT), pastry-making (PM), and dental hygiene technology (DHT), health status was assessed at baseline and yearly for up to 44 mo. Subjects who quit the apprenticeship were contacted and offered a last series of measurements as if they pursued. The effect of various factors-at baseline and during the career program-on quitting was examined. Eighty-nine of 769 subjects (11.6%) quit, of whom 74 participated in this study. In multivariate analysis, a history of hay fever (OR = 1.66, 95% CI = 1.0 to 2.75) and attending the pastry-making program (OR = 2.33, 95% CI = 1.11 to 4.91) were significant determinants for quitting. In the subgroup of AHT, SIS to laboratory animals, hay fever, and shortness of breath were significant determinants by univariate analysis; in PM, the only determinant was age; and in DHT, hay fever. Work-related symptoms during training were not associated with quitting. In a multivariate logistic regression analysis in AHT, including characteristics at baseline and at follow-up, baseline SIS (OR = 2.8, 95% CI = 0.94 to 8.38) and symptoms of asthma in general during follow-up (OR = 2.2, 95% CI = 0.94 to 5.38) were the main determinants for quitting, though they were of borderline significance. We conclude that health-related self-selection out of an apprenticeship with exposure to HMW agents is likely to occur and to cause an attrition bias.

Airway hyperresponsiveness and symptoms of asthma in a six-year follow-up study of childhood asthma

BACKGROUND AND AIM

In an inception cohort study of 457 asthmatic children diagnosed at the age of 3 to 4 years, airway hyperresponsiveness (AHR) was assessed 6 years after first diagnosis in a subgroup of 84 children. Our objective was to associate the level of AHR with the symptomatic asthma status at follow-up.

METHODS

Information on respiratory symptoms and medication use for the previous 6 years was obtained. Children with reported wheezing episodes during the previous year (n = 169) or for > or = 2 years at any time during the follow-up period (n = 85) were eligible for the challenge test.

RESULTS

Among the 254 eligible children, 166 were randomly selected. The parents of 88 of them consented to have their child participate. At the time of assessment of AHR, 19 children (22%) were asymptomatic and 24 others (29%) had symptoms but did not use any medication. Forty-one children (49%) were symptomatic and required medication, including antiinflammatory preparations in 26 instances (31%). All but two children had significant AHR. There was no significant association between the level of AHR and graded symptomatic and medication score. Twenty-four of the 70 children (34%) with greatly enhanced AHR used no medication.

CONCLUSIONS

This study shows that (1) almost all children first diagnosed with asthma 6 years ago and with persisting but not necessarily current symptoms of asthma have increased AHR, which satisfies a proposed epidemiologic definition of asthma; (2) AHR was present in 95% of the 20 currently asymptomatic children; and (3) one third of children with greatly enhanced AHR did not use any treatment.

Longitudinal assessment of airway caliber and responsiveness in workers exposed to chlorine

This longitudinal study (1992-1994) was performed to determine the relation between accidental chlorine exposure and changes in lung function and airway responsiveness in 239 workers in a metal production plant. These workers had taken part in a cross-sectional survey in 1992. In both the initial and the follow-up surveys, history of exposure to chlorine ("puffs"), accidental chlorine inhalation reported to the first-aid unit (gassing incidents), and of chronic symptoms were documented; spirometry and methacholine challenge tests were performed. At follow-up, 211 workers (88.3%) were seen. In workers with 20 pack-years or more of cigarette smoking, the fall in FEV(1) was associated with having had a gassing incident during the follow-up period; the fall in FEV(1)/FVC (%) was predicted by the number of puffs causing mild symptoms between the two assessments. An increase in airway responsiveness (PC(20) decrease > 1.5-fold) was present in 19 workers; it was associated with accidents reported to the first-aid unit during the previous 2 yr (OR: 5.9, 95% CI: 1.1 to 32.3). These findings suggest: (1) an effect on airway function related to the estimated number of puffs with mild symptoms and gassing incidents, mostly among smokers; (2) a detectable increase in airway responsiveness associated with gassing incidents.

Maternal smoking and childhood asthma

The role of maternal smoking as a causal factor for the incidence of childhood asthma is still not clearly established. It was investigated among 3- and 4-year-old-child incident cases confirmed by a 6-year follow-up (n = 294) and cases who no longer had symptoms after diagnosis (n = 110). The study took place in Montréal, Canada, between 1988 and 1997. Persistent and transient cases were compared with their respective controls from the original case-control study of incidence. The odds ratio for heavy maternal smoking adjusted for known risk factors for asthma was 3.84 (95% confidence interval: 1.68, 8.76) among persistent cases and close to one among transient cases.

Rate and cost of hospitalizations for asthma in Quebec: An analysis of 1988/89, 1989/90 and 1994/95 data

The objectives of this study were to evaluate recent trends in the frequency and length of stay of hospitalization for asthma in the province of Quebec and to estimate the costs of asthma hospitalizations. Data were extracted for persons hospitalized for 30 days or less with a primary diagnosis of asthma in all Quebec short-stay hospitals during the years 1988/89, 1989/90 and 1994/95. There were 1.76 asthma hospitalizations per 1000 persons in Quebec in 1988/89, down to 1.44 in 1989/90 and up again to 1.75 in 1994/95. There was a small decrease in mean length of stay when the three data years were compared. In all three years, the rate of hospitalization was particularly high among young boys. In 1994/95, more hospitalizations occurred during the fall months. We estimated the total cost for asthma hospitalization that year to be $18 to $21 million.

Occupational asthma caused by isocyanates: patterns of asthmatic reactions to increasing day-to-day doses

Inhalation challenges to isocyanates are conducted in specialized centers to confirm occupational asthma. The pattern of asthmatic reactions due to consecutively increasing daily doses of isocyanates is unknown. We conducted a study involving 24 subjects who had undergone specific inhalation challenges to isocyanates (toluene diisocyanate [TDI], n = 8; hexamethylene diisocyanate [HDI], n = 10; and methylene diisocyanate [MDI], n = 6) on three or more consecutive days. Challenge tests were given through a closed-circuit apparatus (n = 12) or in small cubicles (n = 12), allowing assessment of the total inhaled dose (concentration x duration). The pattern of asthmatic reactions was described. In addition, dose-response curves were analyzed and tested for their linear and quadratic trends. Four patterns of response were observed: (1) linear (n = 10); (2) minimal effect followed by a brisk change (n = 7); (3) significant change followed by tachyphylaxis or a plateau (n = 4); (4) biphasic (i.e., significant change followed by a reduction in the effect and significant change on the last day of exposure [n = 3]). Subjects with a linear dose-response pattern had been exposed to isocyanates at work for a significantly shorter interval (7.2 +/- 6.7 yr) than subjects with a nonlinear pattern (20.0 +/- 13.1 yr). An analysis of variance covering a 3-d period for all subjects showed a significant linear model for the response (p < 0.0001); there was no quadratic trend. However, when the analysis was done on subjects with four or more days of challenge (n = 10), we found both linear and quadratic significant components. This analysis shows that the most common pattern of asthmatic reactions to inhaled isocyanates generated on consecutive days is linear; however, other patterns are also observed. In some individuals, particularly those in whom more days of challenge are required, we observed in addition to a strong linear component a quadratic component manifested by a brisk change on the last day of exposure.

Comparison of peak expiratory flows and FEV1 in assessing immediate asthmatic reactions due to occupational agents

BACKGROUND

FEV1 is more sensitive than PEF in assessing late asthmatic responses (LAR) after specific inhalation challenges (SIC) with occupational agents. As immediate asthmatic reactions (IAR) mainly involve proximal airways, PEF may, however, be as valid as FEV1.

METHODS

Thirty-seven subjects who experienced an immediate fall in FEV1 of > or =20% during SIC with occupational agents and 20 subjects with fall of < or =10% in FEV1 were included. Both FEV1 and PEF were measured in a random order every 10 min for 1 h after exposure. We corrected PEF (PEFc) for inaccuracies of the mini-Wright meters by the Miller equation.

RESULTS

Maximum changes in PEFc (30+/-11%) were not significantly different from changes in FEV1 (27+/-5%) (P=0.13). Their timings after exposure were 14+/-11 min and 17+/-17 min, respectively (P=0.4). High sensitivity (92%), specificity (95%), accuracy (93%), and positive predictive value (97%) were found for a 20% fall in PEFc to detect a significant IAR. Results were better and not influenced by meter inaccuracies with a cutoff point of 15% change in noncorrected PEF (PEFnc). An absolute decrease in PEF of 70 l/min gave a good discrimination between reactions with and without an asthmatic response.

CONCLUSIONS

PEF is as satisfactory as FEV1 for detecting a significant IAR after exposure to an occupational agent if one considers a cutoff point of 1) 15% fall in PEF 2) 20% fall in PEFc 3) 20% fall and/or 70 l/min decrease in PEFnc.

Skin bruising, adrenal function and markers of bone metabolism in asthmatics using inhaled beclomethasone and fluticasone

Fluticasone propionate (FP) is generally considered to have twice the efficacy of beclomethasone dipropionate (BDP) on a weight-to-weight basis for the control of asthma, and may have lesser effects on adrenal function. However, the effects of FP and BDP on skin integrity and bone metabolism markers require further examination. Sixty-nine asthmatic subjects were enrolled in a double-blind crossover study in which, after a baseline period, they received BDP or FP (at half the dose of BDP) for two 4-month periods each. A questionnaire on skin bruising, a skin examination, tests of adrenal function and of markers of bone metabolism were performed after 2 months of each period. The number of asthma exacerbations was not significantly different for the two treatment periods (eight for BDP and nine for FP), nor were various indices of asthma control. Whereas the frequency of bruising reported by the questionnaire was not different, there were more bruises on examination for BDP (1.6+/-2.5) than for FP (1.2+/-2.3) (p=0.04). Although baseline serum cortisol was not significantly different for the two drugs, the increase in cortisol after cortrosyn was lower for BDP (357+/-158 micromol x dL(-1)) than for FP (422+/-144 micromol x dL(-1)) (p<0.01). Serum osteocalcin levels were significantly lower in subject on BDP (2.8+/-1.7 microg x mL(-1)) than on FP (3.5+/-1.9 ng x mL(-1)) (p=0.003). Other markers of bone metabolism were not significantly altered. The three major side-effects were loosely, but significantly correlated with the periods on BDP and FP. However, skin bruises, increase in cortisol after Cortrosyn and osteocalcin were not significantly correlated for the period on either BDP or FP. In conclusion, whereas fluticasone propionate used at half the dose of beclomethasone dipropionate has a comparable effect on the control of asthma, fluticasone propionate demonstrated fewer side-effects in terms of skin bruising, adrenal suppression and bone metabolism.

Chronic rhinitis in workers at risk of reactive airways dysfunction syndrome due to exposure to chlorine

BACKGROUND

To assess the frequency of chronic upper airways symptoms and to relate the presence of these symptoms to accidental exposure to chlorine and changes in lower airways symptoms, airway function, and bronchial responsiveness in a cohort of workers at risk of sporadic occupational exposure to high concentrations of chlorine.

METHODS

Data were collected on symptom assessment, spirometry, and methacholine challenge tests from 211 workers seen twice at a 2 year interval (1992-4).

RESULTS

The proportion of workers reporting chronic rhinitis was 46.9% in 1992 and 42.2% in 1994. Chronic rhinitis reported in 1994 was significantly associated with acute exposure to chlorine (self reports, p = 0.02; first aid reports, p = 0.001). In a multivariate logistic regression analysis the presence of reported accidents at the first aid unit (one accident, odds ratio (OR) 3.1, 95% confidence interval (95% CI) 1.3 to 7.5; two or more accidents, OR 6.2, 1.1 to 35.8) and of personal atopy (OR 5.5, 2.2 to 10.8) were significant predictors of chronic rhinitis in 1994. Chronic lower airways symptoms were more frequent in 1994 among workers reporting chronic rhinitis on both assessments than in others (p = 0.03) and changes in bronchial responsiveness were more pronounced in those with persistent rhinitis (p = 0.09).

CONCLUSIONS

These results suggest that persistent nasal symptoms in workers at risk of reactive airways dysfunction syndrome could be a useful marker of lower respiratory tract abnormalities.

Specific IgG response to monomeric and polymeric diphenylmethane diisocyanate conjugates in subjects with respiratory reactions to isocyanates

BACKGROUND

Isocyanates are a frequent cause of occupational asthma and can also induce hypersensitivity pneumonitis.

OBJECTIVES

It is still unclear whether antibodies to diphenylmethane diisocyanate (MDI), which are elicited in some subjects with these conditions, are specific for this type of isocyanate. Moreover, preparation of conjugates to human serum albumin (HSA) with the polymeric formulation rather than monomeric MDI might result in improved detection of antibodies.

METHODS

We addressed these issues by testing the sera of 13 subjects with asthma (n = 12) and hypersensitivity pneumonitis (n = 1) induced by MDI (n = 4 or 5, see below) by comparing them with sera obtained from subjects with occupational asthma caused by toluene diisocyanate (TDI; n = 5) and hexamethylene diisocyanate (HDI; n = 2). Conjugate preparations were compared by using SDS-PAGE, absorbance spectral analysis, and isolectric focusing. Immunologic screening was done by ELISA.

RESULTS

Specific IgG antibodies that recognize MDI-HSA conjugates were detected in all but 1 of the MDI-exposed workers and could not be found in TDI-exposed and HDI-exposed workers. The levels of specific IgG antibodies were more elevated when tested against the HSA conjugates formed with polymeric MDI compared with the HSA conjugates formed with monomeric MDI.

CONCLUSION

This study shows that specific IgG antibodies to MDI appear to be specific for MDI without cross-reactivity with TDI and HDI and higher by use of polymeric rather than monomeric MDI-HSA test antigens.

[Quebec spirometry reference values]

Lung volumes forced expiratory flow rates and carbon monoxide diffusing capacity (apnea) were measured in 397 non-smoking, nonatopic, asymptomatic subjects (219 women, 178 men). The equipments and methods for measurements met the ATS criteria. The linear regression of the different variables according to age and height allowed the elaboration of a new set of predictive equations (Quebec). When comparing the different reference values used in North America and Europe, it is found that those of Miller and associates as well as those recommended by the CECA provide the best description of the Quebec situation. However, we would eventually prefer the reference values of Miller and associates over those of the CECA, because they better fit the current ATS criteria and also provide references for smokers. Lung volumes and forced expiratory flow rates of 97 non-smoking, nonatopic, asymptomatic manual workers were measured in the same conditions and submitted to the same comparisons. Quebec predictive values as well as those of Miller and associates isolated the same individuals in the so called abnormal zone. We therefore conclude that Quebec's standards should be preferred in the Province of Quebec pulmonary function laboratories.

Effects of dexamethasone on functional and pathological changes in rat bronchi caused by high acute exposure to chlorine

We assessed the effects of dexamethasone on functional and histological changes after acute exposure to a high level of chlorine gas in an animal model of reactive airways dysfunction syndrome (RADS). Sprague-Dawley male rats were exposed to 1500 ppm of chlorine for 5 min and treated with either dexamethasone (dex; 300 micrograms/kg/day) or saline intraperitoneally for 7 days. Lung resistance (RL), airway responsiveness to inhaled methacholine (MCh), airway wall morphometric measurements, and bronchoalveolar lavage (BAL) cells were assessed over a 2-week period after exposure. Dex administration significantly attenuated both chlorine-induced increased RL and chlorine-induced increased responsiveness to methacholine compared with saline: -2.7 +/- 6.8% vs 102.3 +/- 36.6% change from baseline RL (P < 0.01) and 2.5 +/- 0.6 mg/ml vs 1.2 +/- 0.7 mg/ml in the MCh concentration required to double the RL from baseline (P < 0.01). There was a tendency, albeit nonsignificant, for improvement in some indices of epithelial injury. Dex significantly attenuated the postexposure neutrophilic cellular response in BAL 1 day after exposure (15.8 +/- 4.9% neutrophils in the dex group vs 49.8 +/- 2.7% neutrophils in the saline group) (P < or = 0.001). Our results show that dex administration helps maintain pulmonary function, reduces BAL inflammatory cell number, and tends to improve some morphometric airway wall structure parameters in rats exposed to chlorine.

Determinants of the bronchial response to high molecular weight occupational agents in a dry aerosol form

In occupational challenge tests with isocyanate vapours, bronchial responsiveness is determined by the total dose rather than the concentration or duration of exposure. Whether the same applies for high molecular weight (HMW) agents in powder form is unknown. The aim of this study was to determine whether the total dose of HMW agents in powder form is responsible for the immediate reaction documented in specific challenge tests. Included in the study were nine subjects (seven males and two females) with a diagnosis of occupational asthma proved by specific challenge tests carried out on a preliminary visit. Two challenge tests (using a closed-circuit exposure chamber) were performed at an interval of 2 weeks; the concentrations administered in a random order on these two visits were half and double the one that had caused a 20% fall in forced expiratory volume in one second (FEV1) on a preliminary visit. The duration of exposure was adjusted until a significant fall in FEV1 (target of 20%) occurred. The two concentrations obtained were significantly different, by 2.07+/-0.36-fold (SD). The observed durations of exposure leading to a 20% fall in FEV1 on the two visits also differed significantly by 0.46+/-0.32-fold. Consequently, the cumulative efficient doses were not significantly different between the two visits: 12+/-5.4 and 9+/-5 mg x mL(-1) x min(-1), respectively. The corresponding cumulative dose ratio was 0.96+/-0.61. The expected duration of exposure (10.8+/-24 min) was not significantly different from the observed duration (5.4+/-9 min). The mean and 95% confidence interval for the difference in concentration between the two visits was 1.83-fold (1.48-2.21). In conclusion, the total dose rather than the concentration or duration of exposure per se determines bronchial responsiveness to high molecular weight agents in powder form.

Comparison of serial monitoring of peak expiratory flow and FEV1 in the diagnosis of occupational asthma

Peak expiratory flow (PEF) monitoring is often used to establish the relationship between occupational exposure and asthma. FEV1 has been found to be a better physiologic index than PEF in the measurement of airflow obstruction. The aim of this study was to compare the accuracy of serial monitoring of PEF and FEV1 in the diagnosis of occupational asthma. Twenty consecutive subjects referred for possible occupational asthma were asked to perform serial monitoring of PEF and FEV1 using a portable ventilometer. Two sets of graphs were plotted for both PEF and FEV1: graphs with the best of all values and graphs with the best of two reproducible values. Three observers interpreted both PEF and FEV1 recordings by the visual method in a blind, randomized manner as either compatible with occupational asthma or not. Eleven of the subjects had a positive inhalation challenge test (high-molecular-weight agents, n = 6; low-molecular-weight agents, n = 5). In the case of analysis of the graphs plotted with the best of all values, the sensitivity of the PEF recording interpreted by the three observers was 82, 73, and 73%, and of the FEV1 recording as 55, 55, and 45%; specificity of PEF recording was 89, 100, and 100%, and of FEV1 was 56, 89, and 100%. When an agreement between two of the three readers was required to define occupational asthma, sensitivity and specificity were 73 and 100% for PEF and 55 and 89% for FEV1. Lower sensitivities were found when the same analyses were performed with the graphs plotted with the best of two reproducible values. It was concluded that unsupervised FEV1 is not more accurate than unsupervised PEF monitoring in the diagnosis of occupational asthma. Plotting graphs using the best value gives better diagnostic accuracy than plotting them with the best of two reproducible values.

Immunologic aspects of isocyanate asthma: IL-1 beta, IL-3, IL-4, sIL2R, and sICAM-1

This pilot study investigated serum levels of cytokines and soluble receptors during five positive and five negative isocyanate inhalational challenges. Serum was obtained from 10 individuals with symptoms compatible with isocyanate asthma before isocyanate challenge and the day following their maximal change in pulmonary function after isocyanate challenge. Serum levels of interleukin 1 beta, interleukin 3, interleukin 4, soluble interleukin 2 receptor, and soluble intercellular adhesion molecule 1 were measured and compared. Interleukin 1 beta, interleukin 3, and interleukin 4 were not detected. The mean soluble interleukin 2 receptor and soluble intercellular adhesion molecule 1 levels were not statistically different before and after challenge or between groups. In summary, the cytokines studied are not detectable in peripheral blood during isocyanate inhalation challenge; soluble interleukin 2 receptor and soluble intercellular adhesion molecule 1 are both detectable but do not change significantly after a positive isocyanate challenge.