Significance of lung shrinkage on CXR as a prognostic factor in patients with idiopathic pulmonary fibrosis

OBJECTIVE: The aim of this study was to determine whether the presence of lung shrinkage on CXR can predict diminished survival in patients with idiopathic pulmonary fibrosis (IPF)/usual interstitial pneumonia (UIP). METHODOLOGY: In a hospital-based cohort study 68 subjects diagnosed with IPF/UIP by surgical lung biopsy or at autopsy were observed for a mean of 7.6 years. The radiographic scores from Cherniack's method, pulmonary function tests, arterial blood gas, and haematological data were obtained at initial presentation. Longitudinal radiographic changes over a mean interval of 2.7 years were measured. Survival analysis was performed using Kaplan-Meier and Cox's proportional hazards regression analysis. RESULTS: At some point during the observation period 36 (53%) of 68 patients did not exhibit lung shrinkage and 32 (47%) of 68 patients showed lung shrinkage. Patients with lung shrinkage were more likely to have a diminished survival than those with lung preservation; median survival was 4.4 vs 7.8 years, respectively. Lung shrinkage during the observation period (hazard ratio, 3.89; 95% CI = 1.68-9.01; P= 0.001) was associated with lower rates of survival. CONCLUSION: In patients with IPF/UIP, lung shrinkage on CXR during the observation period was a poor prognostic factor.