Pulmonary fibrosis is defined as progressive based on the combination of radiological, clinical, and functional criteria. Nintedanib can reduce the rate of lung function decline, but no data are available on its effectiveness to hamper disease progression evaluated by these criteria. The primary aim of the study was to assess the number of patients with progressive pulmonary fibrosis (PPF) who no longer meet progression criteria after one year of treatment with nintedanib.

A retrospective, observational, multicenter study was carried out in Italy.

172 patients (91 (52.9%) males) with PPF were recruited, and 135 (78.5%) completed one year of treatment. After one year, 87 (64.4%) patients no longer met INBUILD progression criteria, while 107 (79.3%) did not meet 2022 ATS/ERS/JRS/ALAT guidelines criteria. Nintedanib hampered progression regardless of inclusion criteria, radiological pattern, and etiological diagnosis.

Forced vital capacity (FVC) decline was significantly higher in the 12 months before than in those of treatment (mean, SD): 2512.3 (863.2) ml vs. 2313.6 (821.9) ml; p < 0.0001; 2313.6 (821.9) vs. 2335.7 (865.1); p = 0.82). FVC decline was significantly higher in the year before than in the year of treatment regardless of radiological pattern, etiological subtypes, and respiratory function.

Diarrhea (mostly mild) was the most frequent adverse event (51.7%). A permanent discontinuation of the drug was recorded in 15 (9%) patients.

Nintedanib is effective and safe in patients with PPF. Besides slowing lung function decline, it hampers progression regardless of etiological diagnosis, radiological pattern, respiratory function, and baseline inclusion criteria.