Researchers have proposed a potentially useful way to categorize chronic obstructive pulmonary disease (COPD) at diagnosis based on the classification of specific subtypes, according to a combination of visual and quantitative computed tomography (CT) parameters. Patients from the longitudinal, multicenter, prospective COPDGene cohort study (ClinicalTrials.gov Identifier: NCT00608764) were evaluated, with the results published in CHEST.
The investigators sought to integrate visual and quantitative CT phenotypes with spirometry to develop a comprehensive, nonoverlapping set of COPD subtypes, as well as to assess demographic features, longitudinal disease progression, physiology, and mortality differences among these subtypes. They combined visually defined patterns of emphysema with quantitative CT imaging features and spirometry data, generating a set of 10 nonoverlapping CT subtypes.
A total of 9080 current and former smokers from the COPDGene study who had available volumetric inspiratory and expiratory CT images were evaluated. The 10 discrete, nonoverlapping CT subtypes included the following: no CT abnormality, paraseptal emphysema, bronchial disease, small airway disease, mild emphysema, upper lobe predominant centrilobular emphysema (CLE), lower lobe predominant CLE, diffuse CLE, visual without quantitative emphysema, and quantitative without visual emphysema. The researchers compared baseline and 5-year longitudinal characteristics, along with mortality rates, across all 10 subtypes.
The overall mortality, which differed significantly among the groups (P <.01), was highest in the 3 groups with moderate to severe CLE. Study participants with quantitative but not visual emphysema, and those with visual but not quantitative emphysema, represent unique COPD subtypes with mild disease and with likely different underlying mechanisms, who are at risk for disease progression. In addition, participants with paraseptal and moderate to severe CLE demonstrated considerable, statistically significant progression of emphysema over 5 years compared with those with no CT abnormality (P <.05).
The investigators concluded that combining visual and quantitative CT features reveals diverse underlying pathologic processes in the heterogeneous COPD syndrome and provides a beneficial approach for the reclassification of individuals with COPD.
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Park J, Hobbs BD, Crapo JD, et al; for the COPDGene Investigators. Subtyping COPD using visual and quantitative CT features [published online July 5, 2019]. CHEST. doi:10.1016/j.chest.2019.06.015