Effect of sildenafil added to antifibrotic treatment in idiopathic pulmonary fibrosis

Sildenafil is a phosphodiesterase-5 inhibitor used to treat idiopathic pulmonary arterial hypertension; however, its benefits are unclear in patients with advanced idiopathic pulmonary fibrosis (IPF). We aimed to evaluate its effect as an add-on to antifibrotic agents on clinical outcomes of real-world IPF patients. Among a total of 607 IPF patients treated with antifibrotic agent, 66 concurrently received sildenafil. Propensity score matching was performed to adjust for differences in age, sex, body mass index, forced vital capacity (FVC), and diffusing capacity (DL(CO)) between the sildenafil and no-sildenafil groups. The outcomes of these groups in terms of FVC decline rate, all-cause mortality, hospitalization, and acute exacerbation were compared. Propensity score matching identified 51 matched pairs. The mean age of the patients was 69.5 years and 80.4% were male. Mean FVC and DL(CO) were 51.7% and 29.5% of the predicted values, respectively. The FVC decline rates did not differ significantly (p = 0.714) between the sildenafil (− 101 mL/year) and no-sildenafil (− 117 mL/year) groups. In multivariable analyses adjusted for comorbidities and presence of pulmonary hypertension, sildenafil had no significant impact on all-cause mortality, hospitalization, or acute exacerbation. Sildenafil add-on to antifibrotic treatment had no significant effects on the clinical outcomes of IPF patients.