At week 18 , when glucocorticoid withdrawal was complete , the adjusted mean reduction from baseline in the trough forced expiratory volume in 1 second was 38 ml greater in the glucocorticoid-withdrawal group than in the glucocorticoid-continuation group ( P < 0.001 ) ; a similar between-group difference ( 43 ml ) was seen at week 52 ( P = 0.001 ) .