Table 2.
Summary estimates of diagnostic performance measures of each index test assesses in four studies or more.
| Factor | Number of studies | Total population | Sensitivity (95% CI) |
Specificity (95% CI) |
Positive likelihood ratio (95% CI) | Negative likelihood ratio (95% CI) | Diagnostic odds ratio (95% CI) |
|---|---|---|---|---|---|---|---|
| Socio-demographic | |||||||
| Male | 5 | 4,549 | 0.47 (0.42–0.52) | 0.52 (0.43–0.6) | 0.98 (0.86–1.14) | 1.03 (0.91–1.18) | 0.96 (0.73–1.25) |
| Smoker | 4 | 3,707 | 0.17 (0.08–0.33) | 0.80 (0.70–0.87) | 0.84 (0.56–1.15) | 1.03 (0.94, 1.09) | 0.82 (0.52–1.22) |
| Symptoms | |||||||
| Fever | 4 | 3,849 | 0.61 (0.53–0.69) | 0.56 (0.43–0.68) | 1.41 (1.15–1.78) | 0.70 (0.59–0.82) | 2.06 (1.4–2.91) |
| Cough* | 6 | 4,945 | 0.91 (0.36–0.99) | 0.28 (0.03–0.83) | 1.36 (1.03–2.10) | 0.36 (0.15–0.78) | 4.23 (2.44–6.83) |
| Sputum** | 5 | 4,690 | 0.66 (0.44–0.83) | 0.48 (0.32–0.64) | 1.27 (0.90–1.72) | 0.72 (0.39–1.13) | 1.95 (0.79–4.04) |
| Dyspnea | 6 | 4,946 | 0.63 (0.50–0.75) | 0.49 (0.36–0.63) | 1.27 (0.99–1.63) | 0.75 (0.53–1.01) | 1.77 (0.98–2.97) |
| Chest pain | 7 | 5,044 | 0.49 (0.32–0.66) | 0.64 (0.52–0.75) | 1.37 (1.14–1.60) | 0.79 (0.62–0.93) | 1.76 (1.23–2.44) |
| Signs | |||||||
| Temp ≥ 38 °C† | 7 | 4,593 | 0.40 (0.26–0.56) | 0.88 (0.82–0.91) | 3.21 (2.36–4.23) | 0.68 (0.53–0.82) | 4.80 (2.96–7.38) |
| Pulse rate > 100 min−1‡ | 5 | 4,256 | 0.33 (0.18–0.53) | 0.88 (0.77–0.94) | 2.79 (1.71–4.33) | 0.76 (0.57–0.90) | 3.78 (1.99–6.57) |
| Respiratory rate ≥ 20 min−1¥ | 6 | 4,468 | 0.29 (0.10–0.59) | 0.91 (0.75–0.97) | 3.47 (1.46–7.23) | 0.77 (0.50–0.95) | 4.74 (1.6–11.00) |
| Crackles¶ | 6 | 3,671 | 0.39 (0.28–0.51) | 0.83 (0.65–0.92) | 2.42 (1.19–4.69) | 0.75 (0.61–0.91) | 3.34 (1.13–7.06) |
| Decreased breath sounds | 4 | 3,394 | 0.28 (0.16–0.45) | 0.87 (0.81–0.92) | 2.43 (0.98–4.87) | 0.82 (0.61–1.00) | 3.17 (0.97–7.78) |
| Lab investigations | |||||||
| PCT > 0.25 ng/ml$ | 4 | 6,042 | 0.16 (0.11–0.22) | 0.98 (0.96–0.99) | 7.61 (3.28–15.1) | 0.86 (0.79–0.92) | 8.98 (3.59–18.8) |
| CRP > 20 mg/l§ | 9 | 9,476 | 0.57 (0.42–0.70) | 0.84 (0.70–0.93) | 3.76 (2.30–5.91) | 0.52 (0.42–0.63) | 7.21 (5.08–9.94) |
*Dry cough in one study is included. **Yellowish purulent sputum in three studies are included. †Temperature ≥37.8 °C in two studies are included. ‡Pulse rate ≥100 min−1 in one study is included. ¥Respiratory rate ≥22 min−1 in one study, respiratory rate ≥24 min−1 in two studies are included. ¶Rales in two studies are included. $PCT >0.50 ng/ml in two studies are included. §CRP >50 mg/l in two studies and CRP > 100 mg/l in three studies are included.