Table 2.
Sensitivity, specificity, positive predictive value, likelihood ratios, crude and adjusted DOR of case definitions, and clinical symptoms for all weeks and for epidemic weeks. Influenza sentinel surveillance system, Catalonia, 2008–2018.
| Case Definition | Se † (%) | Sp ‡ (%) | PPV § (%) | Positive LR ¶ (95% CI) |
Negative LR (95% CI) |
Crude DOR ¥ (95% CI) |
Adjusted DOR (95% CI) |
|---|---|---|---|---|---|---|---|
| All weeks | |||||||
| ECDC ILI | 58 | 52 | 36 | 1.22 (1.17–1.26) | 0.80 (0.76–0.84) | 1.52 (1.40–1.66) | 1.52 (1.40–1.66) |
| WHO ILI | 82 | 37 | 37 | 1.30 (1.27–1.33) | 0.48 (0.45–0.53) | 2.68 (2.42–2.97) | 2.69 (2.42–2.99) |
| ECDC ARI | 59 | 50 | 35 | 1.18 (1.14–1.23) | 0.82 (0.78–0.86) | 1.44 (1.33–1.57) | 1.45 (1.33–1.58) |
| Fever | 95 | 18 | 34 | 1.15 (1.14–1.17) | 0.29 (0.25–0.34) | 3.90 (3.30–4.61) | 4.03 (3.38–4.80) |
| Cough | 87 | 22 | 34 | 1.11 (1.09–1.13) | 0.61 (0.56–0.68) | 1.81 (1.61–2.03) | 1.85 (1.65–2.08) |
| Malaise | 67 | 42 | 34 | 1.16 (1.12–1.19) | 0.79 (0.74–0.83) | 1.47 (1.35–1.60) | 1.46 (1.32–1.63) |
| Headache | 51 | 64 | 39 | 1.40 (1.34–1.47) | 0.77 (0.74–0.80) | 1.81 (1.67–1.97) | 1.94 (1.78–2.12) |
| Myalgia | 55 | 58 | 37 | 1.30 (1.24–1.36) | 0.78 (0.75–0.82) | 1.66 (1.53–1.81) | 2.03 (1.84–2.23) |
| Sore throat | 51 | 51 | 32 | 1.03 (0.99–1.07) | 0.97 (0.93–1.01) | 1.06 (0.97–1.15) | 1.07 (0.98–1.16) |
| Shortness of breath | 4 | 92 | 17 | 0.44 (0.36–0.53) | 1.05 (1.04–1.06) | 0.42 (0.34–0.51) | 0.41 (0.34–0.51) |
| Sudden onset of symptoms | 64 | 44 | 34 | 1.14 (1.10–1.18) | 0.82 (0.78–0.87) | 1.38 (1.27–1.51) | 1.38 (1.26–1.50) |
| Coryza | 3 | 94 | 21 | 0.59 (0.48–0.73) | 1.02 (1.01–1.03) | 0.58 (0.46–0.72) | 0.59 (0.47–0.73) |
| Epidemic weeks | |||||||
| ECDC ILI | 58 | 50 | 60 | 1.16 (1.10–1.23) | 0.84 (0.78–0.89) | 1.39 (1.23–1.57) | 1.39 (1.23–1.57) |
| WHO ILI | 82 | 33 | 61 | 1.22 (1.18–1.27) | 0.54 (0.49–0.60) | 2.26 (1.96–2.60) | 2.20 (1.90–2.54) |
| ECDC ARI | 58 | 49 | 60 | 1.15 (1.09–1.22) | 0.84 (0.79–0.90) | 1.36 (1.21–1.54) | 1.36 (1.21–1.54) |
| Fever | 95 | 13 | 59 | 1.10 (1.07–1.12) | 0.38 (0.30–0.46) | 2.92 (2.33–3.66) | 2.78 (2.21–3.50) |
| Cough | 87 | 21 | 59 | 1.10 (1.07–1.13) | 0.63 (0.55–0.72) | 1.75 (1.49–2.06) | 1.78 (1.52–2.09) |
| Malaise | 72 | 31 | 57 | 1.04 (1.00–1.08) | 0.91 (0.83–0.99) | 1.15 (1.01–1.31) | 1.26 (1.08–1.46) |
| Headache | 51 | 57 | 61 | 1.20 (1.12–1.28) | 0.85 (0.81–0.90) | 1.40 (1.24–1.58) | 1.46 (1.29–1.66) |
| Myalgia | 57 | 49 | 59 | 1.11 (1.05–1.17) | 0.89 (0.83–0.95) | 1.25 (1.11–1.41) | 1.52 (1.32–1.75) |
| Sore throat | 51 | 49 | 56 | 1.00 (0.95–1.06) | 1.00 (0.94–1.06) | 1.01 (0.89–1.14) | 1.01 (0.89–1.14) |
| Shortness of breath | 4 | 93 | 39 | 0.50 (0.39–0.65) | 1.04 (1.02–1.06) | 0.48 (0.37–0.63) | 0.53 (0.40–0.70) |
| Sudden onset of symptoms | 63 | 42 | 58 | 1.09 (1.04–1.15) | 0.87 (0.81–0.94) | 1.25 (1.10–1.41) | 1.25 (1.10–1.42) |
| Coryza | 3 | 96 | 50 | 0.78 (0.56–1.07) | 1.01 (1.00–1.02) | 0.78 (0.55–1.08) | 0.70 (0.50–1.00) |
† Sensitivity; ‡ specificity; § positive predictive value; ¶ likelihood ratio; ¥ diagnostic odds ratio.