Suspected ILD among patients with interstitial lung abnormalities linked to high mortality
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About half of patients with interstitial lung abnormalities had suspected interstitial lung disease, with these patients having greater symptoms and more unfavorable clinical outcomes, according to study results.
Researchers classified suspected ILD as interstitial lung abnormalities (ILA) and one or more of the following: definite fibrosis on CT, FVC less than 80% predicted or diffusing capacity of the lungs for carbon monoxide (DLCO) less than 70% predicted after adjusting for emphysema.
“Our study demonstrates that approximately half of those with ILA in COPDGene have suspected ILD, and most adverse outcomes attributable to those with ILA appear to be limited to this group,” Jonathan A. Rose, MD, pulmonologist at Brigham and Women’s Hospital, and colleagues wrote. “Although future longitudinal assessments of those with ILA will be required, our work demonstrates that those with suspected ILD have adverse clinical consequences, including reduced functional status and increased respiratory symptoms, supplemental oxygen use, severe respiratory exacerbations and mortality.”
In a study published in American Journal of Respiratory and Critical Care Medicine, Rose and colleagues analyzed 4,361 adults with a 10-pack-year smoking history from the COPDGene study to find out the frequency, outcomes and risk factors of suspected ILD.
Researchers used multivariable linear, logistic and Cox proportional hazards regression models to compare patients with ILA and suspected ILD with those with ILA alone using results from the St. George’s Respiratory Questionnaire and 6-minute-walk test, as well as supplemental oxygen use, respiratory exacerbations and mortality.
From the total cohort, 239 (5%) patients (mean age, 68.5 years; 49% men) had suspected ILD, including 16% with definite fibrosis, 57% with a FVC less than 80% and 67% with a DLCO less than 70%, whereas 204 (5%) patients (mean age, 68.4 years; 53% men) had ILA without suspected ILD. The other 2,313 patients (mean age, 63.8 years; 50% men) had no ILA.
Through analysis adjusted for age, sex, race, BMI, pack-years of smoking, current smoking status and Global Initiative for Obstructive Lung Disease (GOLD) stage, researchers found that patients with suspected ILD had poorer clinical outcomes than patients with ILA without suspected ILD.
Specifically, these patients had significantly higher St. George’s Respiratory Questionnaire scores (mean difference [MD] = 3.9 points; 95% CI, 0.6-7.1), shorter 6-minute-walk test results (MD = –35 m; 95% CI, –56 m to –13 m), higher percentages of supplemental oxygen use (OR = 2.3; 95% CI, 1.1-5.1) and greater likelihood of suffering from a severe respiratory exacerbation (OR = 2.9; 95% CI, 1.1-7.5).
More patients with suspected ILD died than patients with ILA without suspected ILD (15% vs. 6%), and suspected ILD was linked to a greater mortality risk after adjusting for covariates (adjusted HR = 2.4; 95% CI, 1.2-4.6).
Researchers found that risk factors for suspected ILD included Black race (OR = 2; 95% CI, 1.1-3.3) and pack-years smoking history (OR = 1.2; 95% CI, 1.1-1.3).
Sensitivity analyses demonstrated comparable results, and researchers observed no significant differences between those with ILA without ILD and those with no ILA.
“These findings demonstrate the important need to consider ILD among our patients with COPD and those with a significant smoking history and suggest that further monitoring and studies assessing the effectiveness of interventions might be warranted,” Rose and colleagues wrote.
This study by Rose and colleagues adds to the literature indicating that ILAs and ILD should be assessed together, and a better understanding of ILA progression is necessary, according to an accompanying editorial by Marlies S. Wijsenbeek, MD, PhD, and Guy G. Brusselle, MD, PhD, of the department of respiratory medicine at Erasmus University Medical Center Rotterdam, the Netherlands.
“The findings of Rose and colleagues support that it is time to complement the CT-based ILA classification with a clinical classification of suspected ILD, also incorporating lung function and potentially symptoms and blood biomarkers to identify patients as early as possible in the evolutionary continuum of the different ILDs,” Wijsenbeek and Brusselle wrote. “Such a holistic classification would pave the way for clinical trials investigating the long-term benefits of treating ILDs in the early phases, to improve outcomes for patients with often still poor prognoses.”