Disposition of patients. A total of 55 patients diagnosed with idiopathic pulmonary fibrosis (n = 47) or corticosteroid-resistant fibrotic nonspecific interstitial pneumonia (n = 8) were randomly allocated to receive either a placebo (n = 18), 40 mg of lecithinized superoxide dismutase (PC-SOD) (n = 18), or 80 mg of PC-SOD (n = 19). Of these, 5 patients whose forced vital capacity (FVC) was not determined at baseline or who were not treated with the test agent for ≧20 days were excluded. Therefore, 50 patients were analyzed as a full analysis set. Among these patients, one patient who was not treated by PC-SOD and 11 patients who undertook bronchoalveolar lavage fluid (BAL) analysis were excluded from the per protocol set. While not prohibited in the initial study protocol, performing BAL analysis during the study period was proscribed by the independent data monitoring committee to secure the safety of patients. Therefore, 17 patients (30.9%) were excluded from the study population.