Mild COPD phenotype discovery offers treatment hope

Sep 23 2013

Research indicates that smokers with and without mild chronic obstructive pulmonary disease (COPD) can be classified into distinct phenotypes on the basis of computed tomography (CT) findings.

The study authors, Firdaus Mohamed Hoesein (University Medical Center Utrecht, the Netherlands) and colleagues, say that the findings could help the development of new therapies for COPD that target specific phenotypes.

“Our approach can be used to appreciate COPD more as a heterogeneous group of disorders, instead of one disease,” they comment in Respiratory Medicine.

The study, which was a substudy of the Dutch and Belgium Lung Cancer Screening Trial (NELSON trial), involved 1140 men with a mean age of 62.5 years. All were current or former heavy smokers, with an average smoking history of 41.0 pack–years. Overall, 61.7% of participants did not meet the Global Initiative on Obstructive Lung Disease (GOLD) criteria for COPD, and of those who did, 86% were stage 1.

The team found that 51% of patients fell into the upper quartile for at least one of three CT characteristics: emphysema, air trapping, and airway wall thickening. Of these, 64% fell into a single dominant group, leading to 13% of the 1140 participants being classed as emphysema dominant, 8% as air trapping dominant, and 12% as airway wall thickening dominant.

Furthermore, patients within these three groups displayed significant differences in clinical characteristics. For example, those in the airway wall thickening group were younger, had higher body mass index, and worse forced expiratory volume in 1 second (FEV1) than the other two groups. Symptoms also differed between the groups, with the airway wall thickening dominant group experiencing wheezing significantly more often than both the other groups, and mucus production more often than the air trapping dominant group.

The team also notes that the 206 (18%) patients who had mixed morphology (eg, emphysema and air trapping) had significantly lower spirometric measurements than patients in the dominant groups.

Hoesein and colleagues hope their findings will lead to improved diagnosis and treatment of patients with mild COPD. Noting that several recent large randomized trials failed to find any benefit for pharmacologic treatment on FEV1 decline, they suggest that “[u]sing the CT based types one might show effects of therapy within the groups.”

They conclude: “CT measures of emphysema, airway wall thickening and air trapping may aid in the detection of ‘treatable’ COPD groups (in more advanced disease), and may aid in prognostication regarding pulmonary disease progression and co-morbidities in COPD.”

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