Abstract

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 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). 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) 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 worse long-term outcome among those with IIA and LMW-induced OA.

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