Upper-lobe subpleural irregularity predicts progression and mortality in idiopathic pulmonary fibrosis

Several studies have identified computed tomography (CT) findings predictive of radiological progression in individuals with interstitial lung abnormalities. However, few have assessed their relationship with pathological diagnoses or clinical outcomes in early-stage interstitial lung disease (ILD). This study aimed to identify early CT features predictive of future idiopathic pulmonary fibrosis (IPF), pathological usual interstitial pneumonia (UIP), and mortality.

We retrospectively reviewed patients who underwent surgical or cryobiopsy at our institution between December 2004 and December 2023, all of whom were discussed in a multidisciplinary team. A total of 366 patients met radiologic criteria for early-stage ILD on initial CT. We evaluated the initial CT patterns, pathological findings, multidisciplinary diagnoses, and outcomes. The radiological features of early-stage ILD included subpleural irregularity, reticulation, ground-glass opacities, parenchymal bands, honeycombing, consolidation, and traction bronchiectasis.

The median age at which patients met radiological criteria for early-stage ILD was 65 years (interquartile range [IQR], 12.8 years); 232 were male and 134 were female. The median age at lung biopsy was 69 years (IQR, 12.0 years). Upper-lobe subpleural irregularity was independently associated with IPF diagnosis (odds ratio [OR], 2.84; 95 % CI, 1.64-4.89) and pathological UIP (OR, 3.42; 95 % CI, 1.93-6.07). It also predicted mortality in both IPF patients and the entire cohort (hazard ratio [HR], 5.20; 95 % CI, 2.34-11.6).

Upper-lobe subpleural irregularity on early CT is a significant predictor of progression to IPF, pathological UIP, and increased mortality. It may serve as a valuable imaging biomarker in early-stage ILD evaluation.