Idiopathic pulmonary fibrosis patients with severe physiologic impairment: characteristics and outcomes

Abstract

Research question There is no widely accepted grading system for IPF disease severity, although physiologic impairment based on pulmonary function testing is frequently employed. We sought to describe clinical and functional characteristics as well as outcomes of patients with severe physiologic impairment. Patients and methods IPF patients with severe physiologic impairment defined by FVC ≤ 50% and/or DLco ≤ 30% predicted evaluated in the Inova Advanced Lung Disease Program between 2011 and 2019 were included. Demographic, physiologic, functional treatment and outcome data were collated. Results There were 531 patients with IPF evaluated of whom 242 (46%) had severe physiologic impairment. Mean age was 72 ± 8 years; baseline FVC was 53 ± 17% and DLCO 28 ± 9% of predicted. The mean 6 min walks test (6MWT) distance was 304 ± 121 m with 59% of the patients requiring supplemental oxygen ($${\text{6MWT}}_{{{\text{O}}_{{2}} }}$$ 6MWT O 2 group). There was a poor correlation between the 6MWT distance and both FVC% and DLco%. Patients in the 6MWTRA group had a better transplant-free survival than the $${\text{6MWT}}_{{{\text{O}}_{{2}} }}$$ 6MWT O 2 group (p = 0.002). Patients managed before October 2014 and not receiving antifibrotic therapy had worse outcomes with reduced transplant-free survival compared with patients presenting after this date who did receive antifibrotic therapy (n = 113) (log rank p < 0.0001). Conclusion IPF patients often present with severe physiologic impairment which may be poorly correlated with their functional status. Assessment of IPF disease severity should not be based on physiologic impairment alone, but should also encompass functional status as well as need for supplemental oxygen. Antifibrotic therapy in patients with severe physiologic impairment is associated with improved outcomes.

Regeneration or Repair? The Role of Alveolar Epithelial Cells in the Pathogenesis of Idiopathic Pulmonary Fibrosis (IPF)

“…Upon testing of pulmonary function, a reduced diffusion lung capacity for carbon monoxide is already detectable in the early stage of IPF, followed by the appearance of a restrictive ventilator defect on spirometry and, eventually, reduced total lung capacity [21]. The 6 min walking test may detect desaturation upon exertion, and it has prognostic value, as faster decline in distance covered is associated with higher mortality [22].…”

Derivation and validation of a simple multidimensional index incorporating exercise capacity parameters for survival prediction in idiopathic pulmonary fibrosis

“…Despite its practicality, the model is limited by lack of precision and the overestimation of risk in some cohorts 4 12. Furthermore, the GAP index does not incorporate exercise capacity and therefore, may be of limited value in capturing decline over time 5 9 13…”

Idiopathic pulmonary fibrosis: Current and future treatment

“…24 The 6-min walk test, an easy and straightforward way to determine exercise capacity by having the patient walk as far as possible in 6 min on a flat surface, has prognostic value since faster decline in distance covered is associated with higher mortality. 25,26 The histopathological features of IPF are those of usual interstitial pneumonia (UIP) which appears under the microscope as a heterogeneous patchwork of focal areas of fibrosis with hyperplastic alveolar epithelial cells adjacent to these fibroblastic foci, alternating with less affected areas of normal or nearly normal lung tissue. 27 Lung architecture is disrupted leading to impaired gas exchange (Figure 1).…”

“…The 6‐min walk test, an easy and straightforward way to determine exercise capacity by having the patient walk as far as possible in 6 min on a flat surface, has prognostic value since faster decline in distance covered is associated with higher mortality. 25 , 26 …”