Effect of delayed secondary care referral on morbidity and mortality in idiopathic pulmonary fibrosis patients treated with antifibrotics

Introduction: Patients with confirmed idiopathic pulmonary fibrosis (IPF) are prescribed antifibrotics if they fulfill NICE criteria to reduce symptoms and progression of disease. It is unclear whether delay in beginning treatment will result in poorer outcomes. Methods: Outcome data for patients with eventual IPF diagnosis initiated on antifibrotics were included from Jan 2012 to Jan 2019. Time between date of first radiological finding of interstitial lung disease (ILD) and treatment initiation were identified. FVC and DLCO% were collected at treatment commencement. Inpatient admission events and all-cause mortality were recorded. Cohorts were divided between those who began treatment >12months (+12m) and <12months (-12m) from ILD finding. Student t-test measured differences of FVC and DLCO% between the groups. Logisitic regression models comparing odds of inpatient admission events and mortality were fitted. Results: 34 patients were included in this study. Mean time from first ILD finding to treatment initiation was 20 months. Mean FVC was 2.40 (+12m) vs 2.14 (-12m) (diff 0.26 95% Cl 1.91, 2.53). Mean DLCO% was 41.8% (+12m) vs 40.6% (-12m) (diff 1.2 95% Cl 36.6, 47.2). Odds ratio of inpatient admission events and mortality between the +12m and -12m cohorts was 1.39 (95% Cl 0.343, 5.66, p=0.643). Mean follow-up was 45.4 months. Conclusion: Patients with longer delay in starting antifibrotics actually presented with superior lung function with no significant increase in morbidity or mortality. This suggests different clinical phenotypes of IPF. Further characterisation of these phenotypes may allow targeting antifibrotics to high risk groups.