Idiopathic interstitial pneumonias: do HRCT criteria established by ATS/ERS/JRS/ALAT in 2011 predict disease progression and prognosis?

The objective of the study was to determine whether HRCT criteria for Usual Interstitial Pneumonia (UIP), possible UIP or no-UIP pattern recommended by ATS/ERS/JRS/ALAT guidelines 2011 are able to predict progression and prognosis of the disease in a group of patients with fibrotic idiopathic interstitial pneumonia (IIP). This was a retrospective study conducted with the approval of the ethics committee. Two radiologists at baseline HRCT distributed 70 patients with fibrotic IIP into three groups on the basis of the 2011 guidelines: UIP pattern (group 1), possible UIP pattern (group 2), inconsistent with UIP pattern (group 3). The different abnormalities (honeycombing, reticulation, ground-glass and traction bronchiectasis), fibrotic score (reticulation + honeycombing) and overall CT score were visually scored at baseline and during the follow-up (total HRCT 178). The mortality rate of the three groups was compared. The baseline abnormalities were then correlated with the mortality rate in the UIP group. The inter-observer agreement in the classification of the abnormalities in the three groups was almost perfect (k = 0.92). After consensus, 44 patients were classified into group 1, 13 into group 2 and 13 into group 3. During a mean follow-up of 1386 days, overall CT score, fibrotic score, honeycombing and traction bronchiectasis showed a significant progression in group 1. The mortality rate was significantly higher in group 1 (18 deaths) versus group 2 and 3 (1 death each). In group 1, baseline honeycombing rate higher than 25 %, fibrotic score higher than 30, overall CT score greater than 45 and traction bronchiectasis in more than 4 lobes defined the worst prognosis. HRCT classification based on 2011 guidelines showed high accuracy in stratifying fibrotic changes because in our study UIP, possible UIP and inconsistent with UIP pattern seem to be correlated with different disease progression and mortality rate.