Chronic Obstructive Pulmonary Disease Subtypes. Transitions over Time

Abstract

BackgroundAlthough subtypes of chronic obstructive pulmonary disease are recognized, it is unknown what happens to these subtypes over time. Our objectives were to assess the stability of cluster-based subtypes in patients with stable disease and explore changes in clusters over 1 year.MethodsMultiple correspondence and cluster analysis were used to evaluate data collected from 543 stable patients included consecutively from 5 respiratory outpatient clinics.ResultsFour subtypes were identified. Three of them, A, B, and C, had marked respiratory profiles with a continuum in severity of several variables, while the fourth, subtype D, had a more systemic profile with intermediate respiratory disease severity. Subtype A was associated with less dyspnea, better health-related quality of life and lower Charlson comorbidity scores, and subtype C with the most severe dyspnea, and poorer pulmonary function and quality of life, while subtype B was between subtypes A and C. Subtype D had higher rates of hospitalization the previous year, and comorbidities. After 1 year, all clusters remained stable. Generally, patients continued in the same subtype but 28% migrated to another cluster. Together with movement across clusters, patients showed changes in certain characteristics (especially exercise capacity, some variables of pulmonary function and physical activity) and changes in outcomes (quality of life, hospitalization and mortality) depending on the new cluster they belonged to.ConclusionsChronic obstructive pulmonary disease clusters remained stable over 1 year. Most patients stayed in their initial subtype cluster, but some moved to another subtype and accordingly had different outcomes.

The importance of symptoms in the longitudinal variability of clusters in COPD patients: A validation study

“…The selection of number of clusters was done a priori based on clinical judgement and previous reports, representing the different domains of the disease: age, symptoms, exercise capacity, quality of life and airway obstruction. The present study findings confirmed those from Esteban et al . giving further longitudinal reproducibility to a technique that is becoming more popular for the identification of common clinical characteristics in COPD patients …”

“…Interestingly, the present study findings are similar to the ones from Esteban et al 12 who also found that approximately 28% of their large population of stable COPD patients migrated to another cluster the year after, although there are differences in the study population and in the time of follow-up between the two studies. The present study population included patients from several Spanish centres, who were younger, had less degree of airway limitation and most importantly were followed up for a longer period of time.…”

“…Previous studies already reported that important parameters of the disease change longitudinally: 6MWD, dyspnoea MMRC and FEV 1 . Esteban et al . also reported that the parameters that changed after 1‐year follow‐up in their patients were exercise tolerance, certain lung function measurements and physical activity.…”

“…Interestingly, the present study findings are similar to the ones from Esteban et al . who also found that approximately 28% of their large population of stable COPD patients migrated to another cluster the year after, although there are differences in the study population and in the time of follow‐up between the two studies.…”

“…[4][5][6][7][8][9] Recent data suggest that the most important clinical characteristics of COPD patients could change longitudinally 11 and probably each patient cluster assignment could also change over time. A recent study from Spain reported data on cluster variability in stable COPD patients, 12 suggesting that COPD clusters remain stable over 1 year. To validate these findings, we postulated that clusters of COPD patients are not only stable longitudinally for 1 year but also for 2 years.…”