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Table 2 Univariable and multivariable risk factors for secondary Shigella transmission to 337 contacts within 102 households*, Amsterdam, The Netherlands 2002–2009

From: Risk factors for secondary transmission of Shigellainfection within households: implications for current prevention policy

Exposure Total no. of household contacts Any secondary transmission   Univariable    Multivariable  
  N n % RR 95% CI p value RR 95% CI p value
       Lower Upper    Lower Upper  
Contact characteristics (n=337 contacts)
Total   337 25 7.4 n/a n/a n/a n/a n/a n/a n/a n/a
Age-group
  ≥ 6 years 260 17 6.5 ref. ref. ref. ref. ref. ref. ref. ref.
  0–3 48 3 6.3 1.0 0.3 3.3 0.943 1.0 0.3 3.2 0.979
  4–5 29 5 17.2 2.6 1.0 6.8 0.046 1.3 0.6 3.0 0.527
Gender
  Female 171 17 9.9 ref. ref. ref. ref.     
  Male 166 8 4.8 0.5 0.2 1.2 0.109     
Country of birth
  Netherlands / Other Western 97 7 7.2 ref. ref. ref. ref.     
  Other 236 18 7.6 1.1 0.5 2.3 0.890     
Diarrhoea
  No 228 5 2.2 ref. ref. ref. ref. ref. ref. ref. ref.
  Yes 87 20 23.0 10.5 3.7 29.9 <0.001 8.0 2.7 23.8 <0.001
Hospitalised
  No 336 24 7.1 ref. ref. ref. ref.     
  Yes 1 1 100.0 - - - -     
Household factors (n=102 households)
Household size
  2–4 persons (in 61 households) 128 5 3.9 ref. ref. ref. ref. ref. ref. ref. ref.
  5–6 persons (in 24 households) 96 5 5.2 1.3 0.4 4.8 0.658 1.4 0.4 4.6 0.570
  >6 persons (in 17 households) 113 15 13.3 3.4 1.3 8.7 0.011 3.1 0.9 10.1 0.064
Age of primary case in household
  ≥ 6 years 218 11 5.1 ref. ref. ref. ref. ref. ref. ref. ref.
  0–3 58 6 10.3 2.1 0.8 5.5 0.152 2.6 1.0 7.1 0.061
  4–5 61 8 13.1 2.6 1.2 5.7 0.018 1.9 0.8 4.5 0.163
Gender of primary case in household
  Female 174 9 5.2 ref. ref. ref. ref.     
  Male 163 16 9.8 1.9 0.9 4.1 0.103     
Primary case in household hospitalised
  No 264 21 8.0 ref. ref. ref. ref.     
  Yes 73 4 5.5 1.0 0.9 1.2 0.405     
Time from date of onset to notification of primary case
  ≤1 week 95 9 9.5 ref. ref. ref. ref.     
  1–3 weeks 146 8 5.5 0.6 0.2 1.5 0.262     
  >3 weeks 96 8 8.3 0.9 0.4 2.0 0.761     
  1. *The unit of analysis is the individual contact (n=337) and cluster characteristics are at the household level: household size, age and gender of the primary case in the household, whether they were hospitalised and time from date of onset to notification of primary case, as above.