Clinician specificity for PSI is also poor, with studies finding between 15–30 MRIs are ordered to find one infection.13,19 The use of MRI is an important factor since its lengthy turnaround time of 4–8 hours11 has been cited as “contributing to ED overcrowding.”13 Of the 134 uninfected patients in our derivation cohort, the SIRCH score would reduce the number of unnecessary imaging by 75 compared to clinician suspicion, while the Davis risk factors and any CRP elevation would reduce it by 50 and 30, respectively. This evidence concerns the gene CRP and infection.