Clinical Characteristics of Irritant-Induced Occupational Asthma

Long-term clinical follow-up of irritant-induced occupational asthma

BACKGROUND

Occupational exposure to irritants is associated with poor asthma control, but the long-term clinical characteristics of irritant-induced occupational asthma (IIA) are poorly known.

OBJECTIVE

To evaluate whether any distinguishable features contribute to IIA patients' poor outcomes and whether clinical characteristics change over time.

METHODS

We re-evaluated 28 IIA patients with a median of 6.8 years (IQR 4.6-11.1) after their diagnosis at the Finnish Institute of Occupational Health in 2004-2018. We measured their lung function, non-specific bronchial hyper-responsiveness, inflammation profile and exercise capacity using an ergometric bicycle test. The participants also underwent an Asthma Control Test (ACT) and responded to questionnaires assessing their laryngeal hypersensitivity (LHQ) and dysfunctional breathing (Nijmegen Questionnaires, NQ).

RESULTS

At follow-up, 22 (79%) participants used inhaled corticosteroids, 4 (14%) had asthma exacerbation within 1 year, 11 (39%) had ACT<20 (ie, poor asthma symptom control), 7 (26%) had abnormal spirometry and 8 (36%) had a positive methacholine challenge test result. 17 (61%) participants showed at least one elevated eosinophilic inflammation marker. Six (23%) had an abnormal LHQ score and 7 (26%) had an abnormal NQ score. 15 (58%) participants showed reduced physical capacity that was related to extensive asthma medication, poor asthma symptom control and acute IIA phenotype. A higher ACT score was the only significant change between diagnosis and follow-up (p=0.014).

CONCLUSION

Most of the IIA patients had normal lung function at follow-up, which had only changed a little over time. Reduced physical capacity was a common finding and appears to be related to poor asthma symptom control.

Ecuadorian Provinces with High Morbidity and Mortality Rates Due to Asthma among the Working-Age Population: An Ecological Study to Promote Respiratory Health

Asthma is a significant public health concern. This study identified the provinces with the highest morbidity and mortality rates due to asthma among the working-age population (15-69 years) in the Republic of Ecuador. The secondary objective was to explain the possible differences attributable to occupational exposure. This nationwide ecological study was conducted in 24 provinces between 2016 and 2019. Government databases were used as sources of information. Age-standardized rates were calculated for codes J45 and J46. The hospitalization morbidity rate for asthma decreased from 6.51 to 5.76 cases per 100,000 working-age population, and the mortality rate has consistently been low and stable from 0.14 to 0.15 deaths per 100,000 working-age population. Geographic differences between the provinces were evident. The risk of hospitalization and death due to asthma was higher in the Pacific coast (Manabí with 7.26 and 0.38, Esmeraldas with 6.24 and 0.43, Los Ríos with 4.16 and 0.40, El Oro with 7.98 and 0.21, Guayas with 4.42 and 0.17 and the Andean region (Azuay with 6.33 and 0.45, Cotopaxi (5.84 and 0.48)). The high rates observed in provinces with greater agricultural and industrial development could be national heterogeneity's main determinants and act as occupational risk factors. The contribution of occupational hazards in each province should be examined in depth through ad hoc studies. The findings presented here provide valuable information that should prompt further detailed studies, which will assist in designing public policies aimed at promoting and safeguarding the respiratory health of the population, particularly that of workers. We believe that this study will inspire the creation of regional networks for the research and surveillance of occupational health.

Long-Term Impairment From Irritant-Induced Occupational Asthma

OBJECTIVE

The aim of the study is to assess the long-term physical condition, health-related quality of life, employment, and work ability of irritant-induced asthma (IIA) patients.

METHODS

Forty-three IIA patients completed a follow-up questionnaire a median of eight (interquartile range 4-11) years after asthma diagnosis. We compared their results with those of 43 low-molecular-weight (LMW) sensitizer-induced occupational asthma (OA) patients and those of 206 adult-onset asthmatics in the general population.

RESULTS

Of the IIA patients, 40% reported depressive symptoms. Of the <65-year-olds, 56% were employed, of whom 39% assessed their work ability as limited. IIA patients had more difficulty climbing several flights of stairs than LMW-induced OA patients (70% vs 47%, OR = 4.83 95% CI: 1.51-15.47). Most of the IIA patients' outcomes were inferior to those of the adult-onset asthmatics in the general population.

CONCLUSIONS

IIA prognosis appeared poor but resembled that of LMW-induced OA.

Long-term outcome of occupational asthma with different etiology

PURPOSE OF REVIEW

This review summarizes the recent literature on the long-term outcome of sensitizer-induced and irritant-induced occupational asthma.

RECENT FINDINGS

Recent studies of sensitizer-induced occupational asthma show that after the offending exposure has ceased, most patients report at least partial relief of symptoms. However, in the long term, the diagnosis may negatively impact their careers, incomes, and quality of life. The studies also offer new insights into diisocyanate-induced occupational asthma phenotypes and asthma remission rates. One third of these cases were in remission in long-term after reduction or cessation of exposure. The long-term prognosis of irritant-induced occupational asthma was demonstrated to be poorer than sensitizer-induced occupational asthma. Older age, low fractional exhaled nitric oxide levels and uncontrolled asthma at the time of diagnosis predicted uncontrolled asthma in the long term in patients with irritant and low-molecular-weight sensitizer induced occupational asthma.

SUMMARY

Recent studies provide further evidence of the long-term outcome of different occupational asthma phenotypes and the factors that affect them. These findings help us identify patients at risk of poor asthma outcomes, who need close monitoring and support. It should also be borne in mind that occupational asthma diagnosis may have wider-ranging negative impacts on patients' lives.

[Occupational obstructive airway diseases: How can early diagnosis be made to avoid chronic courses?]

Since abolishing the obligation to terminate the harmful professional activity from January 1st, 2021 onwards for some occupational diseases including obstructive respiratory diseases in Germany, the recognition of occupational diseases coded under 4301, 4302 and 1315 according the Occupational Diseases Ordinance has increased significantly. By the time these diseasese are recognized, they are usually already at an advanced stage. Therefore, early detection will play a greater role in the future, as the statutory accident insurance can offer individual preventive measures in order to minimize the consequences of illness and thus also the socio-economic burden. However, precursors of such obstructive airway diseases are often overlooked. For optimizing early detection, the statutory accident insurance worked out an early notification procedure for the respiratory tract - comparable to the already well-established dermatological procedure. "Early cases" from the pilot regions can be reported there; to qualify for being reported as early cases, patients must persue insured professional activity with potential effects on the respiratory tract and suffer from a disease of the upper or lower respiratory tract according to the ICD-10 code (e.g. J31.0 chronic rhinitis).

Update on irritant-induced occupational asthma

PURPOSE OF REVIEW

In this narrative review, we aim to highlight novel research findings on both acute/subacute irritant-induced asthma (IIA) and chronic exposure IIA (also called 'low dose' IIA).

RECENT FINDINGS

Novel case series showed that acute and subacute IIA cases had similar causal agents (e.g., acid or base aerosols/fumes, dusts, mixtures) but had occurred in different circumstances (accidents vs. regular work). Acute and subacute IIA cases had similar clinical characteristics but poorer short-term outcomes than sensitizer-induced occupational asthma patients. Novel large epidemiological studies reported associations between chronic occupational exposure to irritants and current adult-onset asthma and poor asthma control, and with a specific asthma endotype characterized by neutrophilic inflammation and oxidative stress. Recent studies reconfirmed the association of the use of disinfectants and cleaning products (especially sprays) with IIA. A role for genetic susceptibility has been suggested.

SUMMARY

Recent literature provided further understanding of both acute/subacute and chronic exposure IIA, in terms of causes, possible mechanisms, and consequences such as poor asthma control. Research is needed to clarify several aspects of IIA, including its frequency (still likely underestimated), modulating factors, and mechanisms. Research aiming at improving irritant exposure assessment, including intensity/duration, and determining relevant exposure windows would be welcome.

Long-Term Outcome of Occupational Asthma From Irritants and Low-Molecular-Weight Sensitizers

BACKGROUND

The short-term asthma outcome of irritant-induced asthma (IIA) is poorer than that of low-molecular-weight (LMW) sensitizer-induced occupational asthma (OA).

OBJECTIVES

To evaluate the long-term asthma outcome of IIA and LMW-induced OA and to determine which baseline features are associated with a poor long-term outcome.

METHODS

This follow-up questionnaire study assessed 43 patients diagnosed with IIA and 43 patients with LMW-induced OA at the Finnish Institute of Occupational Health in 2004-2018. The baseline results were analyzed to detect features associated with uncontrolled asthma (Asthma Control Test [ACT] score of ≤19, or ≥2 exacerbations or ≥1 serious exacerbation within 1 year) at follow-up.

RESULTS

The median interval since OA diagnosis was 6.3 years (interquartile range [IQR]: 4.4-11.3 years). Uncontrolled asthma was more frequent with IIA than with LMW-induced OA (58% vs 40%, adjusted odds ratio [OR]: 3.60, 95% confidence interval [CI]: 1.20-10.81). Poor symptom control was the main factor for this difference (median [IQR] ACT score of 18 [15-22] vs 21 [18-23], P = .036, respectively). Among all participants, older age (OR: 1.08 per year, 95% CI: 1.02-1.15), a fractional exhaled nitric oxide (FeNO) value <20 ppb (OR: 5.08, 95% CI: 1.45-17.80), and uncontrolled asthma at baseline (OR: 3.94, 95% CI: 1.31-11.88) were associated with uncontrolled asthma at follow-up.

CONCLUSIONS

Long-term asthma control of IIA appears to be inferior to that of LMW-induced OA. Older age, a low FeNO value, and uncontrolled asthma at baseline might indicate a worse long-term outcome among those with IIA and LMW-induced OA.

Occupational Exposures to Irritants and Sensitizers, Asthma and Asthma Control in the Nutrinet-Santé Cohort

BACKGROUND

The role of chronic occupational exposures to irritants in asthma remains not well-defined. Few studies have examined their associations with asthma and its control.

OBJECTIVE

To study the associations of occupational exposures with asthma and its control, with specific interest for irritants, including disinfectants and cleaning products (DCPs) and solvents.

METHODS

Analyses included 4,469 adults (3,792 with neither asthma nor respiratory symptoms, 677 with current asthma; 75.9% women, mean age 54 years) of a case-control study (2018) from the French NutriNet-Santé cohort. Current asthma was defined by ever asthma with symptoms, medication or asthma attacks in the past 12 months, adult-onset asthma by age at first asthma attack older than 16 years, and uncontrolled asthma was defined by an Asthma Control Test score less than 20. Ever/current exposures were assessed with the Occupational Asthma-specific Job Exposure Matrix. Associations were evaluated by multinomial logistic regressions adjusted for sex, age, smoking status, and body mass index.

RESULTS

Ever exposures to sensitizers (high molecular weight [HMW]: OR 1.53, 95% CI 1.18-2.00; and low molecular weight [LMW]: OR 1.42; 95% CI 1.09-1.87), irritants (OR 1.32; 95% CI 1.03-1.68), and DCPs (OR 1.43; 95% CI 1.10-1.85) were associated with current adult-onset asthma. Significant associations between ever exposures and uncontrolled adult-onset asthma were observed for high molecular weight (OR 2.69; 95% CI 1.52-4.78) and low molecular weight (OR 2.27; 95% CI 1.24-4.37) sensitizers, irritants (OR 2.32; 95% CI 1.36-3.95), and DCPs (OR 2.59; 95% CI 1.48-4.54). Results were similar for current exposures, with higher ORs. No association was observed with solvents.

CONCLUSIONS

Occupational exposures to both sensitizers and irritants were associated with current adult-onset asthma and uncontrolled asthma. Irritant and sensitizing agents should be carefully considered in asthma management.

Irritant-Induced Asthma

Irritant-induced asthma (IIA) is a phenotype of asthma caused by the inhalation of irritant agents. Definite, probable, or possible IIA have been described, depending on the concentration of the inhaled irritants and the onset of respiratory symptoms respective to the time of exposure. Definite IIA represents approximately 4% to 14% of all cases of new-onset work-related asthma. Agents responsible for IIA can be encountered as fumes, gases, aerosols, or dusts. The most frequent are chlorine, nitrogen oxides, sulfur dioxide, ammonia, acetic acid, solvents, and cleaning materials. Although the diagnosis of definite IIA is based on a suggestive clinical history along with evidence of reversible airflow limitation and/or nonspecific bronchial hyperresponsiveness, possible IIA cannot be diagnosed with certainty because the relationship between exposure and the onset of symptoms is difficult to establish. This article reviews the epidemiology, pathophysiology, diagnostic approach, and management of IIA.