COPD stage progression and regression: a multistate transition analysis of the COPDGene cohort

To the Editor: Chronic obstructive pulmonary disease (COPD) is typically diagnosed only after patients develop severe airflow obstruction.1 However, even in its early stages, the disease causes reduced respiratory function and increased mortality.2 A better understanding of the disease course, including the timing of disease progression and possible regression, may improve early detection, allowing time to address risk factors, slow progression, and improve prognosis.2 To better characterize the COPD disease course, we used data from the COPDGene study, a US observational longitudinal cohort of adults aged 45-80 years old who smoked ≥10 pack-years, with and without COPD diagnosis.3 Data were collected at baseline (2008-2011) with 2 5-year follow-up intervals (2012-2016, 2018-2021). We included only individuals who had ever smoked and had post-bronchodilator spirometry values (FEV1 and FVC) for at least 2 time points. Transition probabilities were estimated from 8487 observation pairs (5746 individuals) across the 3 study phases. We categorized each individual at each time point into a severity stage using the GOLD classification (FEV1/FVC ratio; predicted FEV1): GOLD 0 (normal: ≥0.7 and ≥80%, respectively); Preserved Ratio Impaired Spirometry (PRISm; ≥0.7 and