Table 2.
Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for optimal cut-off values of CRP and PCT level to differentiate viral from bacterial LRTI
| CRP cut-off level | PCT cut-off level | CRP and PCT cut-off level | |||||
|---|---|---|---|---|---|---|---|
| ≤ 22 mg/L alone | ≤ 22 mg/L and Headache | ≤ 22 mg/L and Rhinorrhea | ≤ 0.18 ng/mL alone | ≤ 0.18 ng/mL and Headache | ≤ 0.18 ng/mL and Rhinorrhea | CRP ≤ 22 mg/L combined PCT ≤ 0.18 ng/mL and Rhinorrhea | |
| Sensitivity | 0.71 (0.64–0.78) | 0.71 (0.64–0.78) | 0.90 (0.85–0.95) | 0.68 (0.60–0.76) | 0.68 (0.60–0.76) | 0.86 (0.80–0.92) | 0.73 (0.66–0.80) |
| Specificity | 0.77 (0.67–0.87) | 0.77 (0.67–0.87) | 0.63 (0.51–0.75) | 0.78 (0.68–0.88) | 0.78 (0.68–0.88) | 0.61 (0.49–0.73) | 0.88 (0.80–0.96) |
| PPV | 0.87 (0.81–0.93) | 0.87 (0.81–0.93) | 0.84 (0.78–0.90) | 0.88 (0.81–0.94) | 0.88 (0.81–0.94) | 0.83 (0.77–0.89) | 0.93 (0.88–0.98) |
| NPV | 0.54 (0.44–0.65) | 0.54 (0.44–0.65) | 0.73 (0.61–0.84) | 0.52 (0.42–0.61) | 0.52 (0.42–0.61) | 0.65 (0.53–0.77) | 0.59 (0.49–0.69) |
| AUC | 0.74 (0.68–0.80)* | 0.78 (0.71–0.84) | 0.81 (0.75–0.87)** | 0.73 (0.67–0.79)# | 0.75 (0.69–0.82) | 0.80 (0.74–0.86)## | 0.86 (0.80–0.91)& |
**versus *p < 0.0001
##versus #p < 0.0001
**versus &p = 0.0107
##versus &p = 0.020