The Journal of Allergy and Clinical Immunology: In Practice
Original ArticleSevere Occupational Asthma: Insights From a Multicenter European Cohort
Introduction
Severe asthma (SA) imposes a substantial public health burden because the condition has a major impact on patients' quality of life and accounts for a disproportionately large portion of health care costs associated with asthma.1, 2 Clinical practice guidelines advocate the identification and remediation of exposures contributing to asthma severity as a key step in disease management.1, 3 Among potentially modifiable exposures, the workplace environment is likely to hold a notable position because workplace exposures to high-molecular-weight (HMW) and low-molecular-weight (LMW) asthmagenic agents have been associated with an increased risk of poor asthma control and severe exacerbations.4, 5
Sensitizer-induced occupational asthma (OA), a distinguishable phenotype of work-related asthma, is characterized by the de novo inception of asthma or the recurrence of previously quiescent asthma induced by immunologically mediated sensitization to a specific agent at the workplace.6, 7 Enhancing our knowledge of the burden and determinants of severe OA may be relevant from both clinical and health-economic perspectives. Complete avoidance of exposure to the causal agent is the recommended treatment option for OA but is associated with a higher socioeconomic impact as compared with reduction of exposure.10, 11, 6, 8, 9 The severity of asthma at the time of diagnosis has been consistently identified as a risk factor for a worse outcome after removal from exposure.12, 6, 8 However, the determinants of OA severity have so far received little attention.13, 14
The aim of this study was to estimate the burden of severe OA and to identify its determinant factors in a large multicenter cohort of subjects with OA confirmed by specific inhalation challenge (SIC).
Section snippets
Study design and population
This retrospective, cross-sectional, observational study was conducted in an international, multicenter cohort of subjects with OA recruited from 20 tertiary centers in 11 European countries. Eligible subjects were those with a diagnosis of OA ascertained by a positive SIC completed between January 2006 and December 2015. From the 1180 eligible subjects with a positive SIC, 183 subjects with missing data pertaining to the variables used for assessing asthma severity and control were excluded
Population
The population included 997 patients with OA ascertained by a positive SIC result (see Appendix E1 and Figure 1). The demographic, clinical, and functional characteristics of the cohort are presented in Tables I and II. The occupational agents that induced a positive SIC response are summarized in Table E2 (available in this article's Online Repository at www.jaci-inpractice.org).
Severe OA while at work
The prevalence rates of high-level treatment, poor symptom control, 2 or more SA exacerbations during the last 12
Prevalence of severe OA
This cohort study indicates that a substantial fraction of subjects with OA (16.2%; 95% CI, 14.0%-18.7%) experience SA according to the multidimensional European Respiratory Society/American Thoracic Society consensus definition of the disease.1 This estimate is higher than those found in the general adult asthma population in 2 studies that applied the same definition of SA: 4.5% (95% CI, 3.9%-5.1%)21 and 6.3%.22 The prevalence of SA in the general adult asthma population remains, however,
Conclusions
This study shows that the determinants of severe OA include not only potentially modifiable factors (ie “unchanged/persistent” exposure to the causal agent and duration of symptomatic exposure before diagnosis) but also a low sociodemographic status and clinical characteristics (ie, childhood asthma and daily sputum production). Interestingly, data collected in the subset of subjects removed from the causal agent at the time of the diagnostic evaluation suggest that the persistence of SA was
Acknowledgments
European Network for the Phenotyping of Occupational Asthma (E-PHOCAS) investigators: Olivier Vandenplas and Catherine Rifflart (Department of Chest Medicine, Centre Hospitalier Universitaire UCL Namur, Université Catholique de Louvain, Yvoir, Belgium); Pavlina Klusackova (Department of Occupational Medicine, General University Hospital, Charles University, Prague, Czech Republic); David Sherson (Department of Pulmonary Medicine and Occupational Medicine, Odense University Hospital, Odense,
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This work was funded in part by a Task Force of the European Academy of Allergy and Clinical Immunology. O.V. and C.R. were supported by a grant from the Fondation Mont-Godinne. J.S. was supported in part by CIBER de Enfermedades Respiratorias, Instituto de Salud Carlos III, Ministry of Economy and Competitiveness, Spain.
Conflicts of interest: The authors declare that they have no relevant conflicts of interest.