FVC decline predicts death in patients with progressive fibrosing ILD

Patients with idiopathic pulmonary fibrosis (IPF) exhibit a similar course of lung injury with those having other forms of progressive fibrosing interstitial lung disease (ILD), reveals a study, which also shows the association of forced vital capacity (FVC) decline with short-term mortality in this population.

“These data support similarity in the course of lung injury between IPF and other progressive fibrosing ILDs and the value of FVC decline as a predictor of mortality,” the researchers said.

Using a Cox proportional hazards model, the researchers analysed the associations between demographic/clinical variables and mortality (time to death) over 52 weeks by pooling data from the INPULSIS trials and, separately, the INBUILD trial.

Of the 1,061 participants in the INPULSIS trials and 663 in the INBUILD trial, 68 (6.4 percent) and 33 (5.0 percent) died, respectively, over 52 weeks. [Respirology 2022;27:294-300]

In the INPULSIS trials, a relative decline in FVC >10% predicted within 12 months (hazard ratio [HR], 3.77) and age (HR, 1.03 per 1-year increase) contributed to an increased risk of mortality, while baseline FVC % predicted (HR, 0.97 per 1-unit increase) and diffusing capacity of the lungs for carbon monoxide (DLCO) % predicted (HR, 0.77 per 1-unit increase) correlated with a lower risk.

In the INBUILD trial, a relative decline in FVC >10% predicted within 12 months (HR, 2.60) and a usual interstitial pneumonia-like fibrotic pattern on high-resolution computed tomography (HRCT; HR, 2.98) led to a higher mortality risk, while baseline DLCO % predicted (HR, 0.95 per 1-unit increase) correlated with a reduced risk.

Predictor of mortality

These findings were in line with those of previous studies that have consistently shown an increased risk of mortality in patients with fibrosing ILDs whose FVC % predicted declined from baseline by 10 percent within 12 months. [Thorax 2012;67:407-411; Eur Respir J 2016;47:588-596; Arthritis Rheumatol 2017;69:1670-1678; Am J Respir Crit Care Med 2011;184:1382-1389; J Clin Med 2020;9:2499]

“Together with evidence from previous studies, these data support the use of a relative decline in FVC >10% predicted within 12 months as a robust predictor of mortality in patients with fibrosing ILDs,” the researchers said.

The association of lower DLCO % predicted at baseline with a higher mortality risk over 52 weeks was also consistent with earlier studies. [Eur Respir J 2013;42:750-757; BMC Pulm Med 2019;19:192; Respir Res 2019;20:105; Respirology 2020;25:636-643]

One point of interest was the association of lower FVC % predicted at baseline with mortality in the INPULSIS trials, but not in the INBUILD trial.

“This may reflect the inclusion criteria used in the INBUILD trial, which required recent progression of ILD based on decline in FVC or worsening of symptoms and abnormalities on HRCT within the 24 months prior to enrolment, and/or the difference in FVC % predicted at baseline, which was higher in the INPULSIS trials than in the INBUILD trial,” the researchers said.