Table 4.
Hospital Course among Patients Who Were Hospitalized for or Died of 2009 H1N1 Infection, by Pandemic Wave, Wisconsin, 15 April 2009 through 2 January 2010
| Wave 1 | Wave 2 | Pa | |
| Hospital course | |||
| Abnormal radiographic imaging findingsb | 125/230 (54) | 434/773 (56) | .63 |
| Admission to intensive care unit | 59/252 (23) | 221/1077 (21) | .31 |
| Mechanical ventilation, invasive | 36/252 (14) | 119/893 (13) | .69 |
| Acute respiratory distress syndrome | 32/252 (13) | 70/866 (8) | .03 |
| Vasopressor use | 12/252 (5) | 72/859 (8) | .06 |
| Deathc | 9/252 (4) | 46/1076 (4) | .77 |
| Length of stay, median days (range)d | 3.0 (1–43) | 3.0 (1–63) | .46 |
| Length of stayd | |||
| 0–2 days | 98/245 (41) | 330/759 (43) | |
| 3–5 days | 83/245 (35) | 259/759 (34) | .51 |
| ≥6 days | 57/245 (24) | 170/759 (22) | |
| Treatment | |||
| Antivirals | 215/250 (86) | 812/925 (88) | .45 |
| Antibiotics | 204/249 (82) | 713/901 (79) | .33 |
| Time from onset to antiviral treatmente | |||
| <48 h | 82/214 (38) | 367/738 (50) | |
| 48–96 h | 45/214 (21) | 182/738 (25) | <.001 |
| >96 h | 87/214 (41) | 189/738 (26) | |
| Time from admission to antiviral treatmentf | |||
| ≤24 h | 164/214 (77) | 660/745 (89) | <.001 |
| Time from onset to admissiong | |||
| <48 h | 122/250 (49) | 471/839 (56) | |
| 48–96 h | 53/250 (21) | 175/839 (21) | .02 |
| >96 h | 75/250 (30) | 193/839 (23) |
NOTE. Wave 1 refers to 15 April through 30 August 2009; wave 2 refers to 31 August 2009 through 2 January 2010. Patients included were Wisconsin residents who were hospitalized ≥24 h or who died of laboratory-confirmed or probable 2009 H1N1 infection. Data are proportion (%) of patients and deaths unless otherwise stated.
Determined by Pearson χ2, Fisher exact, Cochran-Mantel-Haenszel, or Wilcoxon-Mann-Whitney test.
Radiologist's report includes at least 1 of 3 findings: opacities or infiltrates, consolidation, or pleural effusion, detected by means of chest X-ray or chest computed tomographic scan.
Died of 2009 H1N1 infection as determined by autopsy or attending physician.
Length of stay was calculated using the difference between dates of hospital admission and hospital discharge; results exclude persons who died.
Time from illness onset to receipt of antiviral medication was calculated in hours by using the difference between the date of antiviral treatment initiation and the date of symptom onset.
Time from admission to receipt of antiviral medication was calculated in hours by using the difference between date of antiviral receipt and the date of admission, with date of admission as day 0.
Time from illness onset to admission was calculated in hours by using the difference between date of admission and date of illness onset, with date of onset as day 0.