Table 1.
Characteristics of the controls and patients with laboratory-confirmed, hospital-acquired influenza (HAI) and of the factors associated with HAI in Edouard Herriot Hospital, Lyon (France), in influenza seasons 2004-05, 2005-06 and 2006-07
| Characteristics | Patients with confirmed HAI (N = 11) | Controls (N = 44) | P | Crude ORa (95% CI) |
|---|---|---|---|---|
| Gender, female | 8 (73) | 33 (75) | 1.0 | 0.89 (0.22-3.72) |
| Age, years | 0.99 (0.97-1.02)b | |||
| Median (range) | 66.0 (48.5-85.1) | 78.7 (42.3-86.7) | 0.6 | |
| Type of ward | 1.0 | |||
| Medicine | 8 (73) | 31 (70) | 1.0 (Ref.) | |
| Surgery | 3 (27) | 13 (30) | 0.90 (0.21-3.89) | |
| Chronic pulmonary disease | 2 (18) | 5 (11) | 0.6 | 1.60 (0.31-8.25) |
| Chronic cardiac disease | 5 (45) | 21 (48) | 1.0 | 0.92 (0.26-3.28) |
| Immuno-depression | 2 (18) | 1 (2) | 0.10 | 8.00 (0.73-88.22) |
| Potential influenza source in the unitc | 7 (64) | 13 (30) | 0.08 | 4.06 (1.08-15.33) |
| Individual influenza vaccinationd, e | 2 (20) | 21 (48) | 0.16 | 0.34 (0.069-1.70) |
| Proportion of vaccinated HCW in the unit | 0.10 | |||
| < 35% | 8 (73) | 19 (43) | 1.0 (Ref.) | |
| ≥ 35% | 3 (27) | 25 (57) | 0.16 (0.018-1.32) | |
Data are reported as numbers (%) under descriptive analysis and as OR (95% CI) under logistic regression analysis. Controls were hospitalised patients with ILI and confirmed exclusion of influenza diagnosis after nasal swabbing; they were matched by influenza season (2004-05, 2005-06 and 2006-07). HAI, hospital-acquired influenza; OR, odds ratio; CI, confidence interval; HCW, healthcare workers.
aUnder univariate conditional logistic regression
bPer 1 year older
cPotential sources of exposure to influenza (other patients or HCW) for 5 days before ILI or influenza occurrence in the same ward
dIn current influenza season
eIndividual influenza vaccination was not known in 1 patient