Impact of Interstitial Lung Abnormalities on Disease Expression and Outcomes in COPD or Emphysema: A Systematic Review

Abstract

Background

Both COPD and interstitial lung abnormalities (ILAs) are conditions associated with smoking and age. The impact of coexistent ILAs on the manifestations and outcomes of COPD or emphysema awaits evaluation.

Methods

We searched PubMed and Embase using Medical Subject Headings terms in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

Results

Eleven studies were included in the review. The sample size of the studies ranged from 30 to 9579. ILAs were reported in 6.5% to 25.7% of the patients with COPD/emphysema, higher than that reported in the general populations. COPD/emphysema patients with ILAs were older, mostly male, and had a higher smoking index than those without ILAs. Hospital admission and mortality were increased in COPD patients with ILAs compared to those without ILAs, whereas the frequency of COPD exacerbations was discrepant in 2 of the studies. The FEV₁ and FEV₁% predicted tended to be higher in the group with ILAs, but not significantly in most of the studies.

Conclusion

ILAs were more frequent in subjects with COPD/emphysema than in the general population. ILAs may have a negative impact on hospital admission and mortality of COPD/emphysema. The impact of ILAs on lung functions and exacerbations of COPD/emphysema was discrepant in these studies. Further prospective studies are warranted to provide high-quality evidence of the association and interaction between COPD/emphysema and ILAs.

Keywords:

• COPD
• emphysema
• interstitial lung abnormalities
• review

Abbreviations

6MWD, Six minutes walk distance; ACOS, Asthma-COPD overlap syndrome; AHRQ, Agency for Healthcare Research and Quality; BMI, body mass index; CAT, COPD Assessment Test; COPDGene, Genetic Epidemiology of COPD Study; D_LCO, diffusion capacity of the lung for carbon monoxide; ECLIPSE, Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-points; FHS, Framingham Heart Study; FRC, functional residual capacity; GGO, ground-glass opacity; GOLD, global initiative for chronic obstructive lung disease; HRCT, High Resolution Computed Tomography; IgE, immunoglobulin E; ILAs, interstitial lung abnormalities; ILD, interstitial lung disease; IPF, idiopathic pulmonary fibrosis; KL-6, Krebs Von den Lungen-6; LDCT, Low-Dose Computed Tomography; mMRC, Modified British Medical Research Council; NOS, Newcastle-Ottawa Scale; PFTs, pulmonary function tests; Pi10, square root of wall area of airway with internal perimeter of 10 mm; RB, respiratory bronchiolitis; RVLV, right ventricular to left ventricular; SGRQ, St George’s Respiratory Questionnaire; SP-D, serum surfactant protein D; TLC, total lung capacity; UIP, usual interstitial pneumonia.

Author Contributions

All authors made a significant contribution to the work reported, whether that is in the conception, study design, execution, acquisition of data, analysis and interpretation, or in all these areas; took part in drafting, revising or critically reviewing the article; gave final approval of the version to be published; have agreed on the journal to which the article has been submitted; and agree to be accountable for all aspects of the work.

Disclosure

The authors report no conflicts of interst in this work.

Additional information

Funding

YC.S. is supported by the National Natural Science Foundation of China (81970041, 82170048).