CRP and pneumonia: After adjusting for age, sex, CCI and pneumonia severity, bacterial co-infection was associated with a CRP ≥ 50 mg/L [CRP 50–149: aOR 4.82 (95% CI 1.68–20.34), CRP ≥ 150: aOR 3.92 (95% CI 1.27–17.11)], WBC > 12.0 × 109 cells/L [aOR 4.27 (95% CI 2.12–8.42)], procalcitonin ≥ 2.00 [aOR 8.01 (95% CI 3.46–18.06)] and NLR > 20.0 [aOR 4.90 (95% CI 1.53–13.15)].