Table 1.
Baseline Values for the Decision Model and Ranges Used in Sensitivity Analysis
| Variable | Value at Baseline | Sensitivity Range | Reference |
|---|---|---|---|
| Probabilities | |||
| Influenza in patient presenting with acute onset fever and cough | 0.77 | 0.44 to 0.87 | 7, 13–16, 41, 42 |
| Influenza B, given influenza | 0.11 | 0 to 0.70 | 17 |
| Death from influenza (per 100,000) | 1.8 | 0.4 to 3.1 | 2 |
| Complication requiring antibiotics | 0.10 | 0.05 to 0.17 | 7, 18, 42 |
| Hospitalization | 0.004 | 0.001 to 0.007 | 2, 19, 20 |
| Test characteristics | Manufacturer's insert | ||
| Sensitivity | |||
| Directigen (influenza A) | 0.86 | 0.81 to 0.94 | |
| Directigen (influenza B) | 0.71 | 0.44 to 0.90 | |
| Flu OIA | 0.96 | 0.77 to 1.0 | |
| QuickVue | 0.73 | 0.67 to 0.81 | |
| ZstatFlu | 0.65 | 0.50 to 0.78 | |
| Specificity | |||
| Directigen (influenza A) | 0.87 | 0.86 to 0.93 | |
| Directigen (influenza B) | 1.00 | 0.99 to 1.00 | |
| Flu OIA | 0.64 | 0.48 to 0.79 | |
| QuickVue | 0.96 | 0.93 to 0.99 | |
| ZstatFlu | 0.99 | 0.95 to 1.00 | |
| Antiviral Drugs | |||
| Shortens illness, hours | |||
| Amantadine | 24 | 17.5 to 31.0 | 4 |
| Rimantidine | 24 | 18.5 to 42.5 | 4 |
| Oseltamivir | 24 | 24 to 72 | 7 |
| Zanamivir | 24 | 24 to 72 | 13 |
| Probability of side effects | |||
| Amantadine | 0.09 | 0 to 0.26 | 4, 22–24 |
| Rimantidine | 0.02 | 0 to 0.10 | 4, 22–24, 43 |
| Oseltamivir | 0.10 | 0.075 to 0.11 | 5, 7, 42, 44 |
| Zanamivir | 0 | 0 to 0.10 | 6, 10, 45 |
| Efficacy against complications requiring antibiotics | |||
| Amantadine | 0 | 0 | No data |
| Rimantidine | 0 | 0 | No data |
| Oseltamivir | 0.33 | 0 to 0.45 | 7, 42 |
| Zanamivir | 0.33 | 0 to 0.45 | 21 |
| Average workdays lost from influenza | 3.0 | 0.5 to 5.0 | 46–48 |
| Length of hospitalization, days | 4.3 | 2.0 to 5.0 | 32 |
| Utilities | |||
| Influenza | 0.25 | 0 to 1 | Patient data |
| Hospitalization | 0.20 | 0 to 0.25 | Estimate |
| Side effects | 0.88 | 0.5 to 1.0 | Estimate |
| Costs ($) | |||
| Drugs | |||
| Amantadine | 1.57 | 49 | |
| Rimantidine | 20.40 | 49 | |
| Oseltamivir | 59.54 | 49 | |
| Zanamivir | 48.02 | 49 | |
| Azithromicin | 41.84 | 49 | |
| Amoxicillin | 5.10 | 49 | |
| Tests | |||
| Directigen A/B | 25 | 0 to 25 | List price |
| Flu OIA | 16.5 | 0 to 25 | List price |
| QuickVue | 18 | 0 to 25 | List price |
| ZstatFlu | 14.5 | 0 to 25 | List price |
| Moderate complexity office visit | 46 | 31 | |
| Emergency room visit | 160 | 32 | |
| Hospitalization | 3663 | 3663 to 4957 | 32, 50 |
| Workday | 177 | 0 to 500 | 30 |