The promise in pooled data despite failure to show clear benefit in individual studies of anti-IL-5 therapy may suggest that with proper patient selection, a highly specific group of COPD patients might benefit from anti-IL-5 therapy or that the number needed to treat for IL-5 therapies in COPD is quite high such that individual studies had insufficient power to detect a difference. Here, IL5 is linked to chronic obstructive pulmonary disease.