Fatigue changes in IPF patients measured by the Fatigue Assessment Scale during antifibrotic treatment

Background: Fatigue is a common complaint in patients with idiopathic pulmonary fibrosis (IPF) and has been reported in up to 69% of patients with IPF. Fatigue is also a registered side effect of pirfenidone, one of two approved antifibrotic drugs. The Fatigue Assessment Scale (FAS) was developed for assessment of fatigue in sarcoidosis and validated in sarcoid patients. FAS has only been used little in IPF. Aims: To study the change in FAS after initiation of pirfenidone or nintedanib over a 6 month period. Method: Between April 2017 and January 2018, all incident IPF patients starting antifibrotic treatment were invited to complete FAS before, 4 weeks, 3 and 6 months after initiation of antifibrotic treatment. Baseline characteristics including lung function were registered. Results: 52 patients were included, mean FVC% 84.8, mean DLCO% 51.4. 25 patients started nintedanib; 27 patients started pirfenidone. 64% of patients had a FAS score >22 indicating significant fatigue at baseline. There was no statistically significant difference in FAS score for patients treated with nintedanib or pirfenidone at any time point. FAS score increased statistically significantly during the 6 months. This change was driven by patients without significant fatigue at baseline, who had an increase in FAS score of 8.4 points, whereas patients with significant fatigue at baseline had no statistically significant change. Conclusion: FAS score increased significantly during the 6 months observation period. There was no significant difference in FAS score between the two antifibrotic treatments at any time point. Patients without significant fatigue at baseline developed significant fatigue during the study period.