Table 2. Performance characteristics of the derived ARI classifier.

A combination of the bacterial ARI, viral ARI, and noninfectious illness classifiers were validated using leave-one-out cross-validation in a population of bacterial ARI (n = 70), viral ARI (n = 115), or noninfectious illness (n = 88). Three published bacterial versus viral classifiers were identified and applied to this same population as comparators. Data are presented as number (%).

Clinical assignment
BacterialViralNoninfectious illness
Ramilo et al.Bacterial54 (77.1)4 (3.5)12 (13.6)Classifier-predicted assignment
Viral6 (8.6)101 (87.8)12 (13.6)
Noninfectious illness12 (14.3)12 (8.7)64 (72.7)
Hu et al.Bacterial53 (75.7)4 (3.5)9 (10.2)
Viral9 (12.9)104 (90.4)9 (10.2)
Noninfectious illness8 (11.4)7 (6.1)70 (79.5)
Parnell et al.Bacterial51 (72.8)8 (7.0)11 (12.5)
Viral13 (18.6)94 (81.7)10 (11.4)
Noninfectious illness6 (8.6)13 (11.3)67 (76.1)
Derived ARI classifierBacterial58 (82.8)4 (3.4)8 (9.0)
Viral9 (12.8)104 (90.4)4 (4.5)
Noninfectious illness3 (4.2)7 (6.0)76 (86.3)