Predictive Values Based on Integration of Pretest Probability and Diagnostic Test With Flu Score 3* Using Test and Treatment Thresholds of 10% and 50%, Respectively
| Season/Risk Category | Probability of Influenza (%) | Comment |
|---|---|---|
| Not flu season (2.5%) | ||
| Low risk (0–2) | 0.4 | Neither test nor treat |
| Moderate risk (3) | 2.1 | Neither test nor treat |
| High risk (4–6) | 6.5 | Neither test nor treat |
| Shoulder (10%) | ||
| Low risk (0–2) | 1.9 | Neither test nor treat |
| Moderate risk (3) | 8.4 | Neither test nor treat |
| High risk (4–6) | 23 | Order rapid test. Probability of flu is 84% if positive and 8% if negative. |
| Flu season (30%) | ||
| Low risk (0–2) | 6.8* | Neither test nor treat |
| Moderate risk (3) | 26 | Order rapid test. Probability of flu is 84% if positive and 8% if negative. |
| High risk (4–6) | 54 | Treat empirically via option 1 (consider empiric therapy if high risk for complications) or option 2 (consider rapid test [95% if positive and 25% if negative]). |
↵* Flu score 3 assigns 2 points for fever plus cough, 2 points for myalgias, and 1 point each for duration <48 hours and chills or sweats.