The percentage of participants with serious adverse events was 81.4 % [ 57/70 ] of the steroids group and 80.0 % [ 56/70 ] of the placebo group ( P > .99 ) ; however , participants receiving steroids had an earlier time of onset of their first serious adverse event by 30 days posthepatoportoenterostomy ( 37.2 % [ 95 % CI , 26.9 % to 50.0 % ] of steroids group vs 19.0 % [ 95 % CI , 11.5 % to 30.4 % ] of placebo group ; P = .008 ) .