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The short-term asthma outcome of irritant-induced asthma (IIA) is poorer than that of low-molecular-weight (LMW) sensitizer-induced occupational asthma (OA).To evaluate the long-term asthma outcome of IIA and LMW-induced OA and to determine which baseline features are associated with poor long-term outcome.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.The median interval since OA diagnosis was 6.3 years (interquartile range (IQR) 4.4-11.3). 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=0.036, respectively). Among all participants, older age (OR 1.08 per year, 95% CI 1.02-1.15), a fractional exhaled nitric oxide (FeNO) value20 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.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 worse long-term outcome among those with IIA and LMW-induced OA.

BACKGROUND: Work is a substantial contributing factor of adult-onset asthma. A subtype of occupational asthma (OA) is caused by irritant agents, but knowledge of the clinical outcomes of irritant-induced asthma (HA) is incomplete. OBJECTIVES: To evaluate whether the clinical picture of IIA differs from that of sensitizer-induced OA. METHODS: This retrospective study analyzed acute and subacute IIA patients diagnosed in an occupational medicine clinic during 2004 to 2018. Sixty-nine patients fulfilled the inclusion criteria, and their characteristics were analyzed at the time of the diagnosis and 6 months later. The results were compared with those of 2 subgroups of sensitizer-induced OA: 69 high-molecular-weight (HMW) and 89 low-molecular-weight (LMW) agent-induced OA patients. RESULTS: Six months after the diagnosis, 30% of the patients with IIA needed daily short-acting beta-agonists (SABA), 68% were treated with Global Initiative for Asthma, 2020 report (GINA) step 4-5 medication, and 24% of the patients had asthma exacerbation after the first appointment. HA depicted inferiority to LMW-induced OA in daily need for SABA (odds ratio [OR]: 3.80, 95% confidence interval [CI]: 1.38-10.46), treatment with GINA step 4-5 medication (OR: 2.22, 95% CI: 1.08-4.57), and exacerbation (OR: 3.85, 95% CI: 1.35-11.04). HA showed poorer results than HMW-induced OA in the latter 2 of these features (OR: 2.49, 95% CI: 1.07-5.79 and OR: 6.29, 95% CI: 1.53-25.83, respectively). CONCLUSIONS: Six months after the OA diagnosis, a significant proportion of the patients with IIA remain symptomatic and the majority of these patients use asthma medications extensively suggesting uncontrolled asthma. The short-term outcomes of IIA appear poorer than that of sensitizer-induced OA. (C) 2022 The Authors. Published by Elsevier Inc. on behalf of the American Academy of Allergy, Asthma & Immunology.