Using logistic regression , adjusted for age , ventilation status , and positive culture , the decline rate in log ( PCT ) over the first 72 hours independently predicted hospital and 90-day mortality ( odds ratio [ 95 % confidence interval ] , 2.76 [ 1.10-6 .96 ] , P = 0.03 ; 3.20 [ 1.30-7 .89 ] , P = 0.01 , respectively ) .