Objective Specific inhalation challenge (SIC) as the reference diagnostic test for occupational asthma (OA) is not widely available worldwide. We aimed to develop non-SIC-based models for OA.
Methods Of 427 workers who were exposed to high-molecular-weight agents and referred to OA clinic at Montréal Sacré-Cœur Hospital between 1983 and 2016, we analysed 160 workers who completed non-specific bronchial hyper-responsiveness (NSBHR) tests and still worked 1 month before SIC. OA was defined as positive SIC. Logistic regression models were developed. The accuracy of the models was quantified using calibration and discrimination measures. Their internal validity was evaluated with bootstrapping procedures. The final models were translated into clinical scores and stratified into probability groups.
Results The final model, which included age ≤40 years, rhinoconjunctivitis, inhaled corticosteroid use, agent type, NSBHR, and work-specific sensitisation had a reasonable internal validity. The area under the receiver operating characteristics curve (AUC) was 0.91 (95% CI 0.86 to 0.95), statistically significantly higher than the combination of positive NSBHR and work-specific sensitisation (AUC=0.84). The top 70% of the clinical scores (ie, the high probability group) showed a significantly higher sensitivity (96.4%vs86.9%) and negative predictive value (93.6%vs84.1%) than the combination of positive NSBHR and work-specific sensitisation (p value <0.001).
Conclusions We developed novel scores for OA induced by high-molecular-weight agents with excellent discrimination. It could be helpful for secondary-care physicians who have access to pulmonary function test and allergy testing in identifying subjects at a high risk of having OA and in deciding on appropriate referral to a tertiary centre.
- clinical scores
- diagnostic model
- logistic regression
- occupational sensitizers
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Contributors JA-P initiated the study. AC, CL and JA-P took part in the acquisition and management of data. MT performed the analysis under the supervision of ES, PS-C and GM assisted model evaluation. ES and MT drafted and revised the manuscript. AC, CL, JA-P, PSC, GM and RC critically reviewed the manuscript.
Funding ES is a recipient of the Fonds de recherche du Québec – Santé and the Institut de recherche Robert-Sauvé en santé et en sécurité du travail (FRQS-IRSST) Career Award Program (Research Scholars – Junior 1). This study has been completed with funding from the Fondation Auger and the FRQS-IRSST installation fund for ES; PSC is a recipient of the FRQS Career Award Program (Research Scholars – Junior 1).
Competing interests CL has received consultancy fees from GlaxoSmithKline Inc (Canada), AstraZeneca Canada, Teva Canada Innovation and Merck Canada Inc; research support from GlaxoSmithKline Inc (Canada); lecture fees from AstraZeneca Canada and Merck Canada Inc; and royalties from UpToDate. AC has received research support from Merck Canada Inc and AstraZeneca Canada; lecture fees from Merck Canada Inc; and royalties from UpToDate. GM has received research support from AstraZeneca Canada and lecture fees from Boehringer-Ingelheim. The rest of the authors declare that they have no relevant conflicts of interest.
Ethics approval This study was approved by the Hôpital du Sacré-Cœur de Montréal’s ethics committee.
Provenance and peer review Not commissioned; externally peer reviewed.
Patient consent for publication Not required.
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