Prognosi a lungo termine dell'asma occupazionale

BACKGROUND: Occupational asthma accounts for 16% of adult onset asthma and is caused by a wide range of workplace agents, resulting in numerous at-risk occupations whose exposures are often underestimated. Diagnosis is complex and frequently delayed, requiring a detailed occupational history, lung function testing, immunological tests, and, mostly for those exposed to low-molecular weight agents, the Specific Inhalation Challenge (SIC).The occupational physician plays a key role in health surveillance, early case identification, and initiation of specialist diagnostic pathways, together with preventive measures aimed at reducing exposure, enabling early detection, and limiting the clinical and functional impact in affected workers. Despite this, long-term prognosis is often unfavorable: many patients continue to experience symptoms and bronchial hyperresponsiveness even after exposure cessation. Early removal from the causal agent is the main determinant of a favorable outcome, whereas delayed diagnosis, prolonged exposure, and poor asthma control are associated with poorer prognosis. AIMS: This study aims to evaluate the occupational, clinical, and functional outcome in patients with work-related asthma confirmed by SIC, and to identify potential determinants of remission in order to strengthen preventive strategies. METHODS: The study included 71 patients with a diagnosis of occupational asthma confirmed by SIC performed between 1988 and 2024 at the Respiratory Physiology Unit of the Occupational Medicine Department in Padua. Complete medical records and spirometry, methacholine challenge, FeNO measurement, and at least one follow-up visit ≥12 months after diagnosis were required. Remission was defined as normal spirometry, absence of symptoms, discontinuation of inhaled therapy, and an Asthma Control Test (ACT) score ≥20. SICs were performed according to ERS recommendations, using the actual workplace agent or the suspected inciting sensitizer, and were considered positive when a ≥20% fall in FEV₁ within 7 hours since the beginning of exposure occurred. Prognostic factors were assessed through univariate and multivariate logistic regression models. RESULTS: Patients with occupational asthma confirmed by SIC were followed for a median time of 11.4 years (IQR 5.9–18.5). The median age at diagnosis was 42.7 years, with a clear predominance of males (76.1%) and non-smokers (78.9%). A significant increase in BMI was observed over time (from 23.9 to 26.0 kg/m²; p < .001). In 91.5% of cases, exposure to the causative agent low molecular weight in 97.2% of cases—had ceased at the time of follow-up. Overall, respiratory function showed stability of FEV₁% over time, with an improvement in the FEV₁/FVC% ratio (p = 0.007). A significant improvement in bronchial hyperresponsiveness was also observed (p < .001). FeNO values showed a trend toward reduction (from 36 to 16 ppb; p = 0.075), although the number of available observations was limited. When dividing patients according to disease status at follow-up, 21 were in remission and 50 still had active asthma. Patients with active asthma were older already at the time of diagnosis (46.1 vs 37.9 years; p = 0.006). Cessation of exposure was comparable between the two groups (95.2% vs 90.0%). At diagnosis, the active-asthma group showed a lower FEV₁% (90.7 vs 100.5%; p = 0.002) and a lower FEV₁/FVC% ratio (96.8 vs 101.9%; p = 0.029). These differences persisted at follow-up: FEV₁% was 91.0 vs 102.1% (p < .001), and FEV₁/FVC% was 98.6 vs 102.8% (p = 0.025). The cumulative dose of methacholine required to induce a 20% fall in FEV₁ (PD₂₀ FEV₁) was lower in patients with active asthma, both at diagnosis and at follow-up (p < .001). The ACT score also differed significantly between the two groups (p < .001), confirming the poorer clinical control in the active-asthma group.

BACKGROUND: L’asma occupazionale rappresenta il 16% dell’asma dell’adulto ed è causata da molteplici agenti lavorativi, per cui le categorie professionali a rischio sono numerose e con esposizioni spesso sottovalutate. La diagnosi è complessa e frequentemente tardiva e richiede: anamnesi lavorativa mirata, prove di funzionalità respiratoria, test immunologici, e, soprattutto per gli esposti ad agenti a basso peso molecolare, il test di broncostimolazione specifica (SIC). Il Medico Competente ha un ruolo chiave nella sorveglianza sanitaria, nell’identificazione precoce dei casi e nell’avvio del percorso diagnostico specialistico con misure di prevenzione che mirino a ridurre l’esposizione, ad individuare precocemente la malattia e a limitarne l’impatto clinico e funzionale nei lavoratori già affetti. Nonostante ciò, la prognosi a lungo termine è spesso sfavorevole: molti pazienti mantengono sintomi e iperreattività bronchiale anche dopo l’allontanamento dall’esposizione. SCOPI DELLO STUDIO: Questo studio si prefigge di valutare l’outcome occupazionale, clinico e funzionale dell’asma indotta da agenti lavorativi, in pazienti per i quali la diagnosi di certezza è stata posta mediante SIC e valutare possibili determinanti di remissione, al fine di migliorare gli interventi di prevenzione. RISULTATI: I pazienti con asma occupazionale confermata da SIC sono stati seguiti per un periodo mediano di 11,4 anni (IQR 5,9–18,5). L’età mediana alla diagnosi era 42,7 anni, con netta prevalenza di lavoratori maschi (76,1%) e non fumatori (78,9%). Nel tempo si osserva un incremento significativo del BMI (da 23,9 a 26,0 kg/m²; p < .001). Nel 91,5% dei casi l’esposizione all’agente causale (nel 97.2% dei casi a basso peso molecolare) risultava cessata al momento del controllo. Globalmente, la funzione respiratoria mostra una stabilità del FEV₁% nel tempo, con miglioramento del rapporto FEV₁/FVC% (p = 0.007) e un miglioramento significativo dell’iperreattività bronchiale (p < .001). Il FeNO mostra una riduzione tendenziale (da 36 a 16 ppb; p = 0.075), pur con numeri limitati. Suddividendo i pazienti per stato di malattia al follow-up, 21 risultano in remissione e 50 con asma attiva, dove i pazienti con asma attiva erano più anziani già alla diagnosi (46,1 vs 37,9 anni; p = 0.006). La cessazione dell’esposizione è sovrapponibile nei due gruppi (95,2% vs 90,0%). Il gruppo con asma attiva presentava alla diagnosi un FEV₁% inferiore (90,7 vs 100,5%; p = 0.002) e un indice di Tiffenau più basso (96,8 vs 101,9%; p = 0.029). Anche al follow-up permangono valori peggiori seppur nella norma, ovvero: FEV₁% 91,0 vs 102,1% (p < .001) e FEV₁/FVC% 98,6 vs 102,8% (p = 0.025). La dose cumulativa di metacolina necessaria per provocare una riduzione del 20% del FEV₁ rispetto al valore basale (PD₂₀ FEV₁) risulta più bassa nei pazienti con asma attiva, sia alla diagnosi sia al controllo (p < .001).