PDE4A and chronic obstructive pulmonary disease: Furthermore, post hoc analyses of randomized controlled trials (RCTs) involving COPD patients with chronic bronchitis who received the PDE4 inhibitor roflumilast or placebo in addition to maintenance ICS and long‐acting bronchodilators also demonstrated an association between higher blood eosinophil counts and greater effects of roflumilast on exacerbation prevention.4