Table 3.
—Seasonal Incidence Rates of CF Pulmonary Exacerbations and Estimated Annual Excess Events, July 2003 Through June 2007
| Age Group | Seasona | Incidence Rate per 10,000 Person-Mo | Event Frequency | Person-Mo | Influenza-Attributable Risk per 10,000 Person-Mob (95% CI) | Estimated Excess Annual Events per 10,000 Peoplec |
| Total | Influenza | 595.0 | 18,049.0 | 303,368.0 | 45.4 (34.3, 56.3) | 147.6 |
| Peri-influenza | 568.4 | 19,861.0 | 349,449.0 | … | … | |
| Summer | 549.6 | 25,473.0 | 463,453.0 | … | … | |
| Adults (181 y) | Influenza | 825.4 | 10,311.0 | 124,928.0 | 55.9 (35.6, 76.0) | 181.7 |
| Peri-influenza | 780.5 | 11,362.0 | 145,579.0 | … | … | |
| Summer | 769.5 | 14,792.0 | 192,220.0 | … | … | |
| Children (0-17 y) | Influenza | 433.7 | 7,738.0 | 178,440.0 | 39.9 (27.6, 52.1) | 129.7 |
| Peri-influenza | 416.9 | 8,499.0 | 203,870.0 | … | … | |
| Summer | 393.8 | 10,681.0 | 271,233.0 | … | … |
See Table 1 for an expansion of abbreviations.
Three influenza activity periods were defined by review of US influenza surveillance data.21,22 The influenza season was all months during which ≥ 15% of laboratory tests for influenza virus were positive in the US influenza virologic surveillance system. The peri-influenza season was all months during October through April during which influenzalike illness activity was below epidemic thresholds. The summer season was all months from April through September.
Rates during the summer season were used as the baseline rates for calculation of the influenza season-attributable risk.
Estimates are based on average influenza season of 3.25 mo.