Table 5.
Multivariate Logistic Regression Model Predicting Hospitalization for or Death due to 2009 H1N1 Infection during Wave 2 Compared with Wave 1 of the 2009 Influenza A (H1N1) Pandemic in Wisconsin, 15 April 2009 through 2 January 2010
| Variable | Wave 2 vs wave 1 adjusted ORa (95% CI) |
| Geographic | |
| City of Milwaukeeb | 1.0 |
| Wisconsin, excluding city of Milwaukee | 4.6 (2.96–7.27) |
| Demographic | |
| Age | |
| <18 yearsb | 1.0 |
| 18–49 years | 1.1 (0.74–1.78) |
| ≥50 years | 1.8 (1.08–3.04) |
| Race/ethnicity | |
| White, non-Hispanicb | 1.0 |
| Black, non-Hispanic | 0.3 (0.20–0.56) |
| Hispanic | 0.5 (0.29–0.98) |
| Asian | 0.2 (0.10–0.57) |
| American Indian/Alaskan Nativec | … |
| Otherc | … |
| Clinical | |
| COPDd | 1.5 (0.72–3.04) |
| Hematologic conditiond | 0.5 (0.21–1.22) |
| Neurologic conditiond | 1.78 (0.94–3.37) |
| Hospital course | |
| Acute respiratory distress syndromed | 0.46 (0.26–0.81) |
| Time from onset to antiviral treatment | |
| <48 hb | 1.0 |
| 48–96 h | 0.9 (0.55–1.43) |
| >96 h | 0.4 (0.23–0.56) |
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 and had complete data for all variables. CI, confidence interval; COPD, chronic obstructive pulmonary disease; OR, odds ratio.
ORs are adjusted for the effects of all other variables in this model.
Variables with OR = 1.0 and no 95% CI have been coded as the reference variables.
No hospitalizations or deaths were reported for this race/ethnicity during wave 1.
The reference groups for these ORs are people who do not have the disease or condition.