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Spirometric diagnosis of COPD states unstable, not consistently progressive

New research of ever-smokers shows spirometrically-defined COPD states are not uniformly progressive and can improve with airflow severity staging or resolve spirometric abnormalities over time, according to a study published in Respiratory Research.

“COPD, defined when a certain spirometric threshold of airflow obstruction is met, is generally considered to be progressive, but its natural history is not well established,” Akshay Sood, MD, MPH, from the department of internal medicine at the University of New Mexico School of Medicine, and colleagues wrote. “The longitudinal stability of the diagnosis provided by cross-sectional spirometric exam in smokers at risk for mild obstruction, is not known.”

Sood and associates performed an observational study of participants, primarily women, in the Lovelace Smokers’ Cohort (n = 1,553) over a five-year period to better understand the natural history of spirometrically-defined chronic obstructive pulmonary disease (COPD), and see if COPD states could undergo beneficial transitions.

The researchers investigated four spirometry states: normal postbronchodilator spirometry, COPD stage I, unclassified state, and COPD stage II+, to determine either a decrease in disease severity, including resolution of spirometric abnormalities, or maintenance of non-diseased state. They separately analyzed all-smokers (n = 1553) and subgroups with normal (n = 956) and abnormal (n = 597) spirometry at baseline, then calculated Markov-like model of transition probabilities over a follow-up of five years. 

The investigators found association between all-smokers COPD stage I, unclassified, and COPD stage II+ stages and probabilities of 16%, 39% and 22% for beneficial transitions, and 16%, 35% and 4% for resolution. They found beneficial transitions occurred commonly in new-onset disease compared with pre-existing disease (P < .001). The results showed beneficial transitions among older smokers, men, or those with bronchial hyper responsiveness were less common, while beneficial transitions among Hispanics and smokers with excess weight were more common.

“These findings may help better describe subphenotypes of COPD when studying the underlying mechanisms and genes responsible for progression of disease,” Sood and colleagues conclude. “This understanding could also lead to novel preventive and therapeutic strategies that may help prevent COPD progression or mitigate its severity, particularly during its pre-disease state before disease become established.” – by Savannah Demko

Disclosure: The researchers report no relevant financial disclosures.