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Guideline for the Prevention and Control of Norovirus Gastroenteritis Outbreaks in Healthcare Settings, 2011

Q2: What are the best methods to identify a norovirus outbreak in a healthcare setting?

Evidence Table Q2 - Clinical criteria

Author, Yr (Ref) Study Design Quality Study Objective Population and Setting N Results Comments Ref ID_Data extracted by
Turcios, R; 2006 116 Diagnostic study
 
1,2
To examine how well the Kaplan’s criteria, fever-to-vomiting ratio, diarrhea-to-vomiting ratio, and each component of the Kaplan criteria discriminated between outbreaks due to norovirus and due to bacterial agents. Kaplan’s criteria are:
1. Vomiting in more than half of affected persons
2. Mean (or median) incubation period of 24-48 hrs
3. Mean (or median) duration of illness of 12-60 hrs
4. No bacterial pathogen in stool culture
 
Another objective was to estimate the proportion of all outbreaks reported to the CDC between 1998 and 2000 that could be attributed to norovirus by using the Kaplan criteria alone.
 
The gold standard for comparison was a confirmed norovirus or bacterial etiology by clinical microbiological testing and molecular biological testing.
Outbreaks reported to the CDC between 1998 and 2000. For testing the criteria, only outbreaks of confirmed etiology for which complete data were available were used.
 
Out of a total of 4050 outbreaks, confirmed etiology with complete data were available for 362.
All results % (95% CI) for each criterion
Sensitivity
Kaplan criteria – 68.2(60.0-75.5)
% of patients with vomiting – 88.5(82.0-93.0)
Duration of illness – 85.8(78.9-90.8)
Incubation period – 89.2(82.8-93.5)
Fever-to-vomiting ratio – 90.1(83.6-94.3)
Diarrhea-to-vomiting ratio – 96.6(91.9-98.7)
 
Specificity
Kaplan criteria – 98.6(95.6-99.6)
% of patients with vomiting – 60.7(53.8-67.3)
Duration of illness – 65.0(58.1-71.3)
Incubation period – 69.6(62.9-75.6)
Fever-to-vomiting ratio – 46.6(39.3-53.9)
Diarrhea-to-vomiting ratio – 44.5(37.7-51.5)
 
Likelihood ratio
Kaplan criteria – 48.7
% of patients with vomiting – 2.2
Duration of illness – 2.4
Incubation period – 2.9
Fever-to-vomiting ratio – 1.7
Diarrhea-to-vomiting ratio – 1.7
 
PPV
Kaplan criteria – 97.1(91.2-99.3)
% of patients with vomiting – 60.9(54.0-67.4)
Duration of illness – 62.9(55.8-69.5)
Incubation period – 67.0(59.9-73.4)
Fever-to-vomiting ratio – 55.7(49.0-62.2)
Diarrhea-to-vomiting ratio – 55.3(48.9-61.3)
 
NPV
Kaplan criteria – 81.8(76.4-86.2)
% of patients with vomiting – 88.4(81.9-92.9)
Duration of illness – 86.9(80.4-91.5)
Incubation period – 90.3(84.5-94.2)
Fever-to-vomiting ratio – 86.3(77.7-92.0)
Diarrhea-to-vomiting ratio – 94.9(87.9-98.1)
 
Outbreaks attributable to norovirus using Kaplan criteria
28%
Power and sample size not reported. 348_RA

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