In the 110/233 analyzed patients ( 47.2 % ) with low initial procalcitonin ( < 0.25 g/L ) , suggesting the absence of systemic bacterial infection , those randomized to procalcitonin guidance ( n = 50 ) had a significantly lower adverse outcome rate compared to controls ( n = 60 ) : 4 % vs. 20 % ( absolute difference -16.0 % , 95 % confidence interval ( CI ) -28.4 % to -3.6 % , P = 0.01 ) , and significantly reduced antibiotic exposure [ days ] ( mean 3.7 4.0 vs. 6.5 4.4 , difference -2.8 [ 95 % CI , -4.4 to -1.2 ] , P < 0.01 ) .