Interstitial Lung Abnormalities Linked to Clinical Course in COPD

In patients with chronic obstructive pulmonary disease (COPD), interstitial lung abnormalities (ILAs) are significantly associated with moderate to severe acute disease exacerbations and with an accelerated decline in lung function, according to study results published in CHEST.¹

Investigators conducted a retrospective study between January 1, 2013, and December 31, 2018, at the Seoul Metropolitan Government-Seoul National University Boramae Medical Center — a tertiary referral hospital located in South Korea.¹ The purpose of the study was to clarify the clinical course of disease according to ILA in patients with COPD. ILA was characterized by visual evaluation of chest computed tomography (CT) scans, assessed by 3 readers and 2 pulmonologists. Based on the method suggested by Washko and colleagues, ILA was divided into 4 major radiographic subtypes: (1) centrilobular ILA: predominant centrilobular or peribronchial ground-glass opacities (GGOs) sparing the lung parenchyma; (2) subpleural ILA: reticular, nodular, or GGOs demonstrating a predominantly subpleural distribution; (3) mixed ILA: mixed centrilobular and subpleural abnormalities; and (4) radiographic interstitial lung disease (ILD): extensive radiographic changes consistent with ILD.²

The primary study outcome was the annual incidence of moderate to severe acute exacerbations of COPD, defined as acute worsening of respiratory symptoms leading to the need for additional therapy. The severity of acute exacerbation was categorized as mild, moderate, or severe.  The secondary study outcome was the longitudinal decline in lung function.

All study participants received chest CT scans and longitudinal pulmonary function tests (PFTs). Mean patient age was 65.9 years; 93.4% of the participants were men. Radiologic findings, lung function changes, and history of acute COPD exacerbations were all assessed during the longitudinal follow-up. A total of 363 patients with COPD who had chest CT scans and follow-up PFTs were included in the current study. Overall, 28.4% of these participants and 12.1% of these individuals exhibited definite and equivocal ILA, respectively.

Patients with definite ILA were significantly older than those without ILA or those with equivocal ILA (P =.003). In comparison, individuals without ILA had higher baseline forced expiratory volume in 1 second (FEV₁) and forced vital capacity (FVC) than those with equivocal or definite ILA (P =.025 and P =.032, respectively).

The most common subtype was subpleural ILA in patients with both equivocal ILA (63.6%) and definite ILA (59.2%). ILA scores for those with definite ILA were significantly higher than were ILA scores for those with equivocal ILA (3.±2.6 vs 1.5±1.3, respectively; P <.001).

During the mean 5.4-year follow-up period, ILA was significantly associated with the annual incidence of moderate to severe acute exacerbations of COPD (P =.002) and the risk for frequent COPD exacerbations (adjusted odds ratio, 2.03; P =.045). Further, patients with progressive ILA demonstrated a significantly higher rate of annual decline in FEV₁ and FVC compared with those who demonstrated no change in ILAs or had improved ILAs.

The investigators concluded that ILA was a common radiologic finding in individuals with COPD and was significantly associated with moderate to severe acute exacerbations. The natural course of ILA is heterogeneous and diverse, and its progression was associated with an accelerated decline in lung function.

References

1. Lee TS, Jin KN, Lee HW, et al. Interstitial lung abnormalities and the clinical course in patients with COPD. CHEST. Published online August 13, 2020. doi:10.1016/j.chest.2020.08.017

2. Washko GR, Hunninghake GM, Fernandez IE, et al; for the COPDGene Investigators. Lung volumes and emphysema in smokers with interstitial lung abnormalities. N Engl J Med. 2011;364(10):897-906.