Outcomes and predictors of progression in progressive pulmonary fibrosis

Progressive pulmonary fibrosis (PPF) is a general term for a class of interstitial lung diseases (ILDs) characterized by a progressive fibrosing (PF) phenotype. Patients with PPF have decreased lung function, exercise ability, and quality of life. The purpose of this study was to investigate the clinical characteristics, potential associated factors for disease progression, and survival outcomes of patients in the PPF population.

This study retrospectively reviewed the data of patients diagnosed with ILD between January 2011 and December 2022 at The First Affiliated Hospital of Ningbo University. A PF phenotype was defined based on the criteria that were used in the PPF clinical practice guidelines, which led to the identification of 92 patients with a PF phenotype among the 177 patients with fibrotic ILD. Baseline clinical information and laboratory parameters were collected and analysed in our cohort.

Patients in the PPF group had higher tumour marker levels and lower pulmonary function test results at baseline than did those in the non-PPF group. According to the multivariate logistic regression analysis, age >65 years (OR 2.71, 95% CI 1.26-5.89; p = 0.011), LDH >245 U/L (OR 3.07, 95% CI 1.39-6.78; p = 0.006), CA-153 > 35 U/mL (OR 3.16, 95% CI 1.25-7.97; p = 0.015), FVC <60% predicted (OR 4.82, 95% CI 1.60-14.51; p = 0.005), DLCO <50% predicted (OR 3.21, 95% CI 1.43-7.21; p = 0.005), and the UIP-like pattern on chest HRCT (OR 3.65, 95% CI 1.33-10.07; p = 0.012) were potentially associated with the progression of fibrotic interstitial lung diseases (f-ILDs) to PPF. Furthermore, the PPF group had a poorer survival rate than the non-PPF group (p = 0.0045). According to the multivariate Cox regression analysis, an SPAP ≥ 37 mmHg (HR 2.33, 95% CI 1.09-5.00; p = 0.030) and acute exacerbation (HR 2.88, 95% CI 1.26-6.59; p = 0.012) were identified as significant prognostic factors for mortality in patients with PPFs.

Patients who were older, had high CA-153 and LDH levels, had poor pulmonary function test results, or had a UIP-like pattern on chest HRCT were more likely to have indications for the progression of f-ILD to PPF. Increased SPAP and AE are independent risk factors for the prognosis of PPF patients, so additional attention should be given to such patients.