Table 1.
Average annual incidence and crude and age-adjusted relative risk of influenza-associated hospitalizations among adults by age, by sex, and by race/ethnicity, New Haven County, CT, 2007–2011 (N = 1094)
| Population* | Number (%) of cases | Crude average annual incidence** | Relative risk and 95% CI | P-value | Age-adjusted relative risk and 95% CI | |
|---|---|---|---|---|---|---|
| Age category | ||||||
| 18–49 | 374 115 | 340 (31·1) | 22·72 | Reference | Not applicable | |
| 50–64 | 171 416 | 238 (21·8) | 34·71 | 1·53 (1·29–1·80) | <0·001 (trend) | Not applicable |
| 65+ | 123 972 | 516 (47·26) | 104·06 | 4·58 (3·99–5·25) | Not applicable | |
| Sex | ||||||
| Male | 316 520 | 413 (37·8) | 32·62 | Reference | – | Reference |
| Female | 352 983 | 681 (62·2) | 48·23 | 1·48 (1·31–1·67) | <0·001 | 1·35 (1·20–1·53) |
| Race/ethnicity*** | ||||||
| White (non-Hispanic) | 478 657 | 673 (61·5) | 35·15 | Reference | – | Reference |
| Black (non-Hispanic) | 73 409 | 226 (20·7) | 76·97 | 2·19 (1·88–2·55) | <0·001 | 2·77 (2·39–3·21) |
| Hispanic | 84 123 | 173 (15·8) | 51·41 | 1·46 (1·24–1·73) | <0·001 | 2·20 (1·89–2·56) |
*
Population estimates obtained through the 2010 Census.
**
Overall incidence was calculated as the number of cases within the category dividing by the total population within the category. Average annual incidence was then calculated for the 4 study season as per 100 000 person-years.
***
Twenty-two (2·0%) cases were either in other race/ethnicity categories or the data on race/ethnicity were missing.