Predictive factors of progression in mild fibrosing interstitial lung disease patients with gender-age-physiology score of 3 or less.

BACKGROUND

The prognostic factors in mild fibrosing interstitial lung disease (FILD) have not been established.

METHODS

We retrospectively attempted to identify predictive factors of annual progression in mild FILD with gender-age-physiology (GAP) score of 3 or less using logistic regression analysis. Annual FILD progression was defined as meeting any two or more of the following conditions: 1, more than 10% decrease in forced vital capacity (FVC) or 15% decrease in diffusing capacity of the lungs for carbon monoxide (D); 2, worsening of dyspnea; 3, worsening of fibrotic change on CT at 1 year after admission.

RESULTS

Univariate analysis showed that diagnosis of connective tissue disease-associated ILD, CT-definite usual interstitial pneumonia (UIP) pattern, composite physiologic index, FVC, D, lowest SpO and decrease in SpO, and walk distance in the 6-minutes walk test (6MWT), chronic pulmonary emphysema assessment test (CAT) score, and some variables in Short-Form 36 were significantly associated with incidence of annual progression. Multivariate analysis showed that independent predictive factors were diagnosis of idiopathic pulmonary fibrosis (IPF) and fibrotic hypersensitivity pneumonitis (HP), CT-definite UIP pattern, lowest SpO and decrease in SpO in the 6MWT, and CAT score. In logistic regression analysis among 63 patients with non-IPF-ILD, diagnosis with fibrotic HP, lowest SpO and decrease in SpO in the 6MWT, and CAT score were also independent risk factors for annual FILD progression.

CONCLUSIONS

Exercise-induced hypoxia, patient-reported outcome, radiological UIP pattern, and diagnosis with fibrotic HP are independent predictors of annual progression in mild FILD.