Outcome of Subjects With Idiopathic Pulmonary Fibrosis Who Fail Corticosteroid Therapy* Implications for Further Studies

To evaluate the outcome of subjects with idiopathic pulmonary fibrosis (IPF) whose conditions clinically deteriorate while receiving corticosteroid therapy, we studied 12 of these subjects (7 male, 5 female) who received subsequent therapy with intravenous (IV) pulse cyclophosphamide (CPX). Seven of the 12 study subjects died during the course of therapy. Six of these subjects died of respiratory failure, and one died of cholecystitis. Among those who died, the mean age at diagnosis was 63 years compared with 57 years in those who have continued to survive (p = 0.29). Smoking status and pack-years of cigarette smoking were similar between those subjects who died and those who continue to survive. However, subjects who died received CPX for a mean of 6 months, while subjects still living have received CPX for a mean of 16 months (p = 0.01). Subjects who died were given CPX a mean of 64 months after the onset of symptoms, compared with a mean of 50 months for subjects who are still alive (p = 0.57). Interestingly, there were no significant differences in measures of pulmonary function between living and dead subjects. In fact, measures of lung function and gas exchange remained stable in both groups throughout the period of observation. These data suggest that (1) measures of lung function may not be a reliable indicator of patient mortality in end-stage IPF, and (2) while not statistically significant, these data raise the possibility that duration of symptomatic disease may play a role in the outcome of IPF patients receiving alternative therapeutic agents after failure of corticosteroid therapy. In future intervention trials, controlling entry criteria for duration of disease may prove helpful in determining the effects of these agents on the disease process. These data do not permit a determination of the effect of CPX in patients with IPF.