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Table 2 Risk factors for Salmonella Enteritidis infections in humans, Ontario, Canada, 20072009 (n = 1,932 cases)

From: Incidence, distribution, seasonality, and demographic risk factors of Salmonella Enteritidis human infections in Ontario, Canada, 2007–2009

Variable a) IRR b) 95% CI c) P-value d)
Year 2007 Reference - -
  2008 1.17 1.05-1.31 0.005
  2009 1.18 1.06-1.32 0.003
Season Fall Reference - -
  Spring 1.14 1.01-1.29 0.040
  Summer 1.06 0.93-1.20 0.377
  Winter 1.06 0.93-1.20 0.413
Age (years) 0-4 Reference - -
  5-9 0.64 0.52-0.78 < 0.001
  10-19 0.44 0.34-0.51 < 0.001
  20-29 0.51 0.43-0.60 < 0.001
  30-39 0.34 0.28-0.40 < 0.001
  40-49 0.31 0.26-0.37 < 0.001
  50-59 0.33 0.28-0.40 < 0.001
  ≥ 60 0.31 0.26-0.37 < 0.001
Sex Female Reference - -
  Male 0.95 0.87-1.04 0.273
Intercept 0.00002 0.00002-0.00003 < 0.001
  1. a) Multi-level mixed-effects Poisson regression model using adaptive Gaussian quadrature. Public health unit (PHU) was included as a random intercept. Variance of PHU random effects = 0.074 [95% CI = 0.036-0.153]. Dependent variable: number of Salmonella Enteritidis cases by year, season, age group, sex, and PHU. Offset: natural log-transformed year-, age group-, sex-, and PHU-based population size estimates. b) IRR: Incidence rate ratio for categorical independent variables, in which the incidence rate (IR) in the category of interest was compared to the IR in the reference category. c) CI: Confidence interval of the IRR. d) Statistically significant at P ≤ 0.05.