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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

From: Influenza vaccination of healthcare workers in acute-care hospitals: a case-control study of its effect on hospital-acquired influenza among patients

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)
  1. 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.
  2. aUnder univariate conditional logistic regression
  3. bPer 1 year older
  4. cPotential sources of exposure to influenza (other patients or HCW) for 5 days before ILI or influenza occurrence in the same ward
  5. dIn current influenza season
  6. eIndividual influenza vaccination was not known in 1 patient