Volume 17, Number 9—September 2011
Research
Estimating Effect of Antiviral Drug Use during Pandemic (H1N1) 2009 Outbreak, United States
Table 4
Estimated number of influenza antiviral drugs prescribed for treatment, after adjusting for prescriptions for prophylaxis, nonadherence, and personal stockpiling, pandemic (H1N1) 2009 outbreak, United States
| Influenza antiviral drug* | No. prescriptions, by patient age group† |
Total | ||
|---|---|---|---|---|
| 0–17 y | 18–64 y | >65 y | ||
| Oseltamivir | 2,152,915 | 2,979,711 | 297,700 | 5,430,326 |
| Zanamivir |
57,065 |
78,980 |
7,891 |
143,936 |
| Subtotal‡ | 2,209,980 | 3,058,690 | 305,591 | 5,574,262 |
*These antiviral drugs were prescribed in a variety of forms (e.g., capsules, tablets, syrup, and inhaled powder). The estimated numbers came from the IMS database (3), which records ≈73% of all prescriptions filled by >50,000 US-based retail pharmacies. IMS then proportionately extrapolates their data, based on populations served by pharmacies, to provide weekly estimates of all prescriptions filled in the U.S. for these drugs. The IMS Health Xponent database does not cover in-hospital prescriptions.
†These subtotals, by age group, are the estimates of prescriptions filled to treat pandemic (H1N1) 2009–related clinical illness, after removing the prescriptions filled for prophylaxis and for patients who failed to adhere to drug regimen or prescriptions filled for personal stockpiles (see Table 1). The total number of prescriptions filled, before adjustments, was 8,177,542 (Table 1). Note that ≈3% of prescriptions filled during this period did not have age of patient recorded, and we omitted those prescriptions from our calculations.
‡These subtotals, by age group, were the estimates used to calculate the hospitalizations averted as shown in Table 5.
