Clinical characteristics and prognostic factors of fibrotic nonspecific interstitial pneumonia

Aim: Several studies have reported favorable outcomes of nonspecific interstitial pneumonia (NSIP); however, its prognosis and prognostic factors remain unclear. This study aimed to determine the outcomes of fibrotic NSIP and the prognostic factors for progression, relapse, and survival. Methods: In this retrospective study, we reviewed the clinical data of 204 patients diagnosed with fibrotic NSIP by surgical lung biopsy at Samsung Medical Center. The factors associated with survival and disease progression or relapse were determined using Cox proportional hazard analysis. Results: The median age of patients was 54years and 67 (33%) patients were male. Also, 47 patients (23%) were current or ex-smokers. In all, 141 (69%) patients were diagnosed with idiopathic NSIP, while 63 (31%) patients were associated with connective tissue diseases. Progression or relapse was observed in 100 (49%) patients. The 5-year and 10-year survival rates were 94.6% and 90.4%, respectively. The factors associated with disease progression and relapse were diffusing capacity for carbon monoxide (DLco) <60% [adjusted hazard ratio (HR), 1.739; 95% confidence interval (CI), 1.036-2.921; p=0.036], bronchoalveolar lavage (BAL) lymphocyte >15% (adjusted HR, 0.592; 95% CI, 0.352-0.994; p=0.047), and treatment with corticosteroid and azathioprine (adjusted HR, 0.556; 95% CI, 0.311-0.955; p=0.048). Disease progression or relapse was associated with mortality (adjusted HR, 7.135; 95% CI, 1.499-33.971; p=0.014). Conclusion: Preserved lung function, BAL lymphocytosis, and treatment with corticosteroids and azathioprine were associated with lower risks of disease progression and relapse, which were risk factors for mortality.