ACEI use was significantly associated with lower mortality at 90 days ( HR 0.46 , 95 % CI 0.30-0 .71 , P < 0.001 ) , and an increase in renal replacement therapy-free days ( P < 0.001 ) , intensive care unit-free days ( P < 0.001 ) and hospital free-days ( P < 0.001 ) after adjusting for baseline covariates .