Table 3.
Multilevel likelihood ratios for different serum C-reactive protein intervals.
| Serum CRP (mg/L) |
Pneumonia (n = 557) |
Other lower respiratory tract infections∗
(n = 366) |
LR+ |
|---|---|---|---|
| >250 | 171 | 7 | 16.3 (7.7–34.4) |
| 225–250 | 40 | 5 | 5.3 (2.1–13.4) |
| 200–225 | 32 | 4 | 5.3 (1.9–15.0) |
| 175–200 | 53 | 17 | 2.0 (1.2–3.5) |
| 150–175 | 58 | 13 | 2.9 (1.6–5.3) |
| 125–150 | 46 | 23 | 1.3 (0.8–2.1) |
| 100–125 | 49 | 30 | 1.1 (0.7–1.6) |
| 75–100 | 31 | 42 | 0.5 (0.3–0.7) |
| 50–75 | 19 | 60 | 0.2 (0.1–0.3) |
| 25–50 | 27 | 67 | 0.2 (0.1–0.4) |
| <25 | 20 | 98 | 0.1 (0.0–0.2) |
CRP, C-reactive protein; LR, likelihood ratio.
∗Other lower respiratory tract infections included acute bronchitis and acute exacerbations of COPD.