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Table 2 Results of the cohort study: attack rates among those exposed and not-exposed to various food items on 5–7 August, relative risk as measure of association

From: Protracted outbreak of S. Enteritidis PT 21c in a large Hamburg nursing home

Date, meal, food item Exposed Not exposed RR 95% CI AF
  ill not ill AR (%) ill not ill AR (%)    
Cohort from units 1 and 9, n = 181 (variable denominator due to missing data), only those with RR>2 shown:
   5-Aug, lunch, "light meal" 10 63 15.9 9 118 7.6 2.08 0.89–4.86 28%
   5-Aug, afternoon, cake 17 128 13.3 2 53 3.8 3.52 0.84–14.70 64%
   6-Aug, lunch, "light meal" 11 47 23.4 8 134 6.0 3.92 1.68–9.15 43%
   6-Aug, afternoon, cake 17 125 13.6 2 56 3.6 3.81 0.91–15.93 66%
   6-Aug, dinner, cold cuts 16 116 13.8 3 65 4.6 2.99 0.91–9.87 56%
   7-Aug, afternoon, cake 16 125 12.8 3 56 5.47 2.39 0.73–7.87 49%
Cohort from units 1, 2, 4 and 9, n = 378 (variable denominator due to missing data), all food items shown:
   5-Aug, afternoon, cake 38 306 13.3 4 70 5.7 2.17 0.80–5.89 49%
   6-Aug, afternoon, cake 38 303 13.3 4 69 5.5 2.29 0.84–6.21 51%
   7-Aug, afternoon, cake 37 303 12.2 5 68 6.8 1.78 0.73–4.38 39%
   6-Aug, lunch, "light meal" 20 123 16.3 22 253 8.7 1.87 1.06–3.29 22%
  1. AR, attack rate; AF, attributable fraction