Not all spirometrically-defined COPD cases unfold the same way, a study published in Respiratory Research says.

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.