Persistent eosinophilia common in COPD

By Joanna Lyford, Senior medwireNews Reporter

More than one-third of patients with chronic obstructive pulmonary disease (COPD) have persistent eosinophilia, researchers report in the European Respiratory Journal.

The finding of persistent eosinophilia was associated with certain characteristics that suggest less severe COPD, say the authors, although they admit this needs to be confirmed in other cohorts.

The research was a substudy of ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate End-points), a cohort study involving COPD patients aged 40 to 75 years.

Of 1483 study participants who provided blood for eosinophil counts, 554 (37.4%) had eosinophil levels of 2% or higher throughout the 3-year study period, report Umme Kolsum, from the University of Manchester, UK, and colleagues.

Compared with other participants – ie, those with eosinophil levels below 2% (13.6%) and those with intermittent eosinophilia (49.0%) – patients with persistent eosinophilia were slightly older, were more likely to be male and less likely to be current smokers. They also had a higher forced expiratory volume in 1 second % predicted and fat-free mass index, more favourable scores on the St George’s Respiratory Questionnaire and modified Medical Research Council questionnaire and a lower BODE (body mass index, airflow obstruction, dyspnoea, exercise capacity) index.

Also, during follow-up, emphysema progression was significantly greater in patients with eosinophil levels below 2% than in other groups. Using different cutoffs to define eosinophilia did not substantially alter the results; neither did excluding current smokers from the analysis.

Kolsum and colleagues remark that the proportion of COPD patients in ECLIPSE with persistently elevated eosinophils was similar to that in 203 COPD-free controls; this suggests “normal eosinophil recruitment into the blood in COPD”, they write.

Noting that previous studies have found that higher eosinophil levels in COPD are associated with increased corticosteroid responsiveness, the authors say that the finding of persistently elevated eosinophils may be “a simple predictor of more lung eosinophils, and hence increased likelihood of corticosteroid responsiveness.”

They conclude: “Targeted therapies against eosinophilic inflammation, such as anti-interleukin-5, may have greater benefits in COPD patients with persistent blood eosinophilia.”

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