Adults aged 40-85 years , with moderate-to-severe COPD , at least one acute exacerbation of COPD , and a sputum eosinophil count of 30 % or more within the previous year , were randomly assigned ( 1:1 ) via computer-generated permuted block randomisation ( block size of four ) , with an interactive voice or web-response system , to receive placebo or 100 mg benralizumab subcutaneously , every 4 weeks ( three doses ) , then every 8 weeks ( five doses ) over 48 weeks .