Progression in Fibrotic Interstitial Lung Diseases: Prevalence and Indicators in the Initial Evaluation in a Brazilian Multicentric Cohort.

OBJECTIVE

This retrospective study aimed to determine the prevalence of progression in fibrotic interstitial lung disease (ILD) and the findings at diagnosis most associated with progression after two years of follow-up in a large Brazilian cohort.

METHODS

This was a retrospective multicenter observational study in Brazil. Progression was defined after two years of follow-up. We excluded patients with an initial peripheral oxygen saturation (SpO2) of less than 88% or an initial forced vital capacity (FVC) of less than 45%. Diagnoses were made by multidisciplinary discussion. Patients with idiopathic pulmonary fibrosis were included for comparison. At least one of the following events was indicative of progressive ILD: (1) a relative decrease in FVC of 10% or more, (2) worsening dyspnea, (3) a greater extent of fibrotic findings on high-resolution computed tomography (HRCT), (4) initiation of oxygen, and (5) death attributed to ILD. Logistic regression analysis was used to identify risk factors for progressive fibrosis.

RESULTS

The mean age of patients was 61.7±12.3 years, and 69.5% had Velcro crackles. The mean FVC was 71.6±15.8%, and 26.1% showed honeycombing on HRCT. After two years of follow-up, 40.5% of patients (n=154) showed disease progression. Fibrotic hypersensitivity pneumonitis (FHP) was the most progressive disease (52%), and connective tissue disease-associated ILD (CTD-ILD) was the least progressive (25%). Multivariate analysis showed that a higher score for dyspnea, crackles, and SpO2 at rest ≤94% and ≤85% at the end of exercise were significant indicators of progression. Diffusing lung capacity for carbon monoxide (DLCO) was measured in 172 cases, with values <55% predicting a high odds ratio for progression (OR=4.03; 2.10-7.69).

CONCLUSION

In Brazil, FHP is the most progressive disease and CTD-ILD is the least progressive after two years of follow-up. The degree of dyspnea, crackles, SpO2 at rest and during exercise, and DLCO at baseline are associated with progressive disease.