Selection of population controls for a Salmonella case-control study in the UK using a market research panel and web-survey provides time and resource savings.
Timely recruitment of population controls in infectious disease outbreak investigations is challenging. We evaluated the timeliness and cost of using a market research panel as a sampling frame for recruiting controls in a case-control study during an outbreak of Salmonella Mikawasima in the UK in 2013. We deployed a web-survey by email to targeted members of a market research panel (panel controls) in parallel to the outbreak control team interviewing randomly selected public health staff by telephone and completing paper-based questionnaires (staff controls). Recruitment and completion of exposure history web-surveys for panel controls (n = 123) took 14 h compared to 15 days for staff controls (n = 82). The average staff-time cost per questionnaire for staff controls was £13·13 compared to an invoiced cost of £3·60 per panel control. Differences in the distribution of some exposures existed between these control groups but case-control studies using each group found that illness was associated with consumption of chicken outside of the home and chicken from local butchers. Recruiting market research panel controls offers time and resource savings. More rapid investigations would enable more prompt implementation of control measures. We recommend that this method of recruiting controls is considered in future investigations and assessed further to better understand strengths and limitations.
Field Epidemiology Service,Public Health England (PHE),UK.
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P
Mook
Field Epidemiology Service,Public Health England (PHE),UK.
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S
Kanagarajah
Field Epidemiology Service,Public Health England (PHE),UK.
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H
Maguire
Gastrointestinal, Emerging and Zoonotic Infections Department,PHE,London,UK.
G K
GK
Adak
Centre for Infectious Disease Surveillance and Control,PHE,London,UK.
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Dabrera
Field Epidemiology Service,Public Health England (PHE),UK.
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A
Waldram
Centre for Infectious Disease Surveillance and Control,PHE,London,UK.
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R
Freeman
Statistics,Modelling and Economics Department,PHE,London,UK.
A
A
Charlett
Field Epidemiology Service,Public Health England (PHE),UK.
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I
Oliver
D016022:Case-Control Studies; D004196:Disease Outbreaks / Q000517:prevention & control / Q000706:statistics & numerical data; D020407:Internet; D040541:Marketing; D011634:Public Health / Q000379:methods*; D012480:Salmonella Infections / Q000453:epidemiology* / Q000382:microbiology / Q000517:prevention & control; D019779:Salmonella enterica; D006113:United Kingdom / Q000453:epidemiology
Case-control studies; Salmonella; epidemiologic research design; outbreaks