Baseline characteristics and survival of patients with idiopathic pulmonary fibrosis (IPF): analysis from the Swedish IPF registry

Background: Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal fibrosing lung disease of unknown aetiology. The Swedish IPF-registry (SIPFR) was established in 2014. Aim: To explore patient characteristics, the effect of anti-fibrotic treatment and mortality in SIPFR. Method: Patients enrolled 2014-2019 were included. We compared GAP stage 1 as mild physiological impairment against other proposed criteria: FVC ≥75%, DLCO ≥55%, TLC ≥65%, and composite physiological index (CPI) ≤ 50. Antifibrotic treatment were grouped into pirfenidone, nintedanib, and patients switching treatment. Results: Of the 415 SIPFR patients (median age 73.0 years, 69.2% male, median follow-up 25 months), 38.5% patient were classified as 9mild9 using GAP stage 1. There was a modest agreement between GAP stage 1 and CPI ≤ 50 (k = 0.54). Sixty-eight percent of the patients (n=282) received antifibrotic treatment for more than 6 months (pirfenidone 34.9%, nintedanib 27.2%, patients switching treatment 5.8%). In patients with GAP stage ≥ 2, those receiving nintedanib had better (p=0.049) survival than those receiving pirfenidone, especially in GAP stage 2 (p=0.022). The cumulative mortality rate in the whole cohort in year 1, 2, 3, 4 and 5 was 91%, 79%, 64%, 59% and 42%, respectively. Baseline lung function (FVC%, FEV1%, FEV1/FVC%, DLCO%, TLC%, CPI), 6 minute-walking test, GAP stage and BMI were all significant predictors of mortality. Conclusion: Composite measures including lung function may be useful in predicting outcome. Patients receiving nintedanib has better survival than those receiving pirfenidone, but only in moderate to severe IPF-patients.