The best model fit for antibiotic use on admission (c-index 0.896) (Table 4) was achieved for otitis media (OR 4.5, 95% CI 2.1–9.4), CRP on admission (OR 1.7, 95% CI 1.5–2.0), and septic appearance (OR 8.95, 95% CI 1.5–54.1). This evidence concerns the gene CRP and otitis media.