FIG 2.

Example of how measurement of PCT and CRP levels in combination strengthens the performance of biomarkers in pediatric SIRS. Data in figure are derived from the report by Simon et al. (33). In that study of 69 children with SIRS, 24 had bacterial infections (pretest probability, 39%). (A) Use of PCT alone had a positive LR (LR+) of 2.65, increasing the posttest probability to 60%, and a LR− of 0.43, decreasing the posttest probability to 22%. (B) Use of CRP alone had a LR+ of 1.63 (posttest probability, 50%) and a LR− of 0.10 (posttest probability, 6%). (C) Use of the combination of PCT and CRP had a LR+ of 4.32 (posttest probability, 74%) and a LR− of 0.043 (posttest probability, 3%). Discordant CRP and PCT results (not shown) had a LR of 0.27 to 0.70 (posttest probability, 15 to 30%).