Interactions between Cigarette Smoking and the Natural History of Idiopathic Pulmonary Fibrosis
Cigarette smoking is known to have deleterious effects on the respiratory tract. However, the correlation between smoking and the incidence and the course of interstitial lung diseases is equivocal. Previous reports have emphasized the role of cigarette smoking habits in the pathogenesis of adult pulmonary histiocytosis X, desquamative interstitial pneumonia, or asbestosis. Furthermore, there is evidence that cigarette smoking is associated with x-ray and pathologic changes consistent with the diagnosis of interstitial fibrosis, and experimental lung fibrosis has been elicited in dogs by cigarette smoke with a dose-response relationship. In contrast, there are several lines of evidence that cigarette smoke may have a protective effect with regard to the development of other types of interstitial lung diseases. A higher prevalence of hypersensitivity pneumonitis has been observed in nonsmokers than in smokers and a strong negative correlation has been found between smoking habits and the prevalence of serum precipitins among farmers. The incidence of sarcoidosis may be reduced among cigarette smokers. In the experimental bleomycin model, cigarette smoke reduced lung fibrotic changes. ventolin inhaler
Cigarette smoking is known to increase the number of intraalveolar inflammatory cells and furthermore to activate these cells. Patients with IPF are often smokers. Therefore, it is conceivable that there is a relationship between cigarette smoking and the course of IPF. In this context, a series of patients with IPF were evaluated with respect to smoking habits, clinical presentation, PFTs, BAL cells, short-term glucocorticoid responsiveness and survival. In view of previously observed better survival rates and higher glucocorticosteroid responsiveness among female patients, the data also have been assessed with regard to sex.