Paggiaro P L, Vagaggini B, Bacci E, Bancalari L, Carrara M, Di Franco A, Giannini D, Dente F L, Giuntini C
2nd Medical Clinic, University of Pisa, Italy.
Eur Respir J. 1994 Apr;7(4):761-7. doi: 10.1183/09031936.94.07040761.
Several studies on the prognosis of occupational asthma have shown that a significant proportion of patients continue to experience asthmatic symptoms and nonspecific bronchial hyperresponsiveness after cessation of work. The determinants of this unfavourable prognosis of asthma are: long duration of exposure before the onset of asthma; long duration of symptoms before diagnosis; baseline airway obstruction; dual response after specific challenge test; and the persistence of markers of airway inflammation in bronchoalveolar lavage fluid and bronchial biopsy. The relevance of immunological markers in the outcome of occupational asthma has not yet been assessed. Further occupational exposure in sensitized subjects leads to persistence and sometimes to progressive deterioration of asthma, irrespective of the reduction of exposure to the specific sensitizer, and only the use of particular protective devices effectively prevents the progression of the disease. A long-term follow-up study of toluene diisocyanate (TDI)-induced asthma showed that the improvement in bronchial hyperresponsiveness to methacholine occurred in a small percentage of subjects and only a long time after work cessation. Bronchial sensitivity to TDI may disappear, but non-specific bronchial hyperresponsiveness often persists unchanged, suggesting a permanent deregulation of airway tone. Steroid treatment significantly reduces nonspecific bronchial hyperresponsiveness only when started immediately after diagnosis.
多项关于职业性哮喘预后的研究表明，相当一部分患者在停止工作后仍持续出现哮喘症状和非特异性支气管高反应性。哮喘这种不良预后的决定因素包括：哮喘发作前的暴露时间长；诊断前症状持续时间长；基线气道阻塞；特异性激发试验后的双重反应；以及支气管肺泡灌洗液和支气管活检中气道炎症标志物的持续存在。免疫标志物在职业性哮喘预后中的相关性尚未得到评估。致敏个体的进一步职业暴露会导致哮喘持续存在，有时还会逐渐恶化，无论对特定致敏原的暴露是否减少，只有使用特定的防护设备才能有效预防疾病进展。一项关于甲苯二异氰酸酯（TDI）诱发哮喘的长期随访研究表明，一小部分受试者的支气管对乙酰甲胆碱的高反应性有所改善，且仅在停止工作很长时间后才出现。支气管对TDI的敏感性可能消失，但非特异性支气管高反应性通常保持不变，这表明气道张力存在永久性失调。类固醇治疗只有在诊断后立即开始时才能显著降低非特异性支气管高反应性。
