Published: 23 April 2021
Authors: Yet H. Khor, MBBS, PhD Lawrence Gutman, MD Nebal Abu Hussein, MD Kerri A. Johannson, MD Ian N. Glaspole, MBBS, PhD Sabina A. Guler, MD Manuela Funke-Chambour, MD Thomas Geiser, MD Nicole S.L. Goh, MBBS, PhD Christopher J. Ryerson, MD
Source: This abstract has been sourced from NZ Respiratory Research Review Issue 201
Hypoxemia is a cardinal feature of fibrotic interstitial lung disease (ILD). The incidence,
progression, and prognostic significance of hypoxemia in patients with fibrotic ILD
currently is unknown.
What are the epidemiologic features of hypoxemia and its additive prognostic value
in a current risk prediction model of fibrotic ILD?
We identified 848 patients with fibrotic ILD (258 with idiopathic pulmonary fibrosis
[IPF]) in five prospective ILD registries from Australia, Canada, and Switzerland.
Cumulative incidence of exertional and resting hypoxemia from the time of diagnosis
was estimated at 1-year intervals in patients with baseline 6-min walk tests, adjusted
for competing risks of death and lung transplantation. Likelihood ratio tests were
used to determine the prognostic significance of exertional and resting hypoxemia
for 1-year mortality or transplantation when added to the ILD-GAP model. The cohort
was divided into derivation and validation subsets to evaluate performance characteristics
of the extended model (the ILD-GAP-O2 model), which included oxygenation status as a predictor.
The 1-, 2-, and 5-year overall cumulative incidence was 6.1%, 17.3%, and 40.1%, respectively,
for exertional hypoxemia and 2.4%, 5.6%, and 16.5%, respectively, for resting hypoxemia,
which were significantly higher in patients with IPF compared with patients without
IPF (P < .001 for both). Addition of exertional or resting hypoxemia to the ILD-GAP model
improved 1-year mortality and transplantation prediction (P < .001 for both). The ILD-GAP-O2 model showed improved discrimination (C-index, 0.80 vs 0.75) and model fit (Akaike
information criteria, 400 vs 422) in the validation cohort, with comparable calibration.
Patients with IPF have higher cumulative incidence of exertional and resting hypoxemia
than patients without IPF. The extended ILD-GAP-O2 model provides additional risk stratification for 1-year prognosis in fibrotic ILD.
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