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Letter
Computer-assisted Telephone
Interview Techniques
To the Editor: Fox et al. used computer-assisted telephone interview
(CATI) techniques in an outbreak of cryptosporidiosis (1).
Australian health agencies have used CATI for several years. A case-control
study during an outbreak of Salmonella Mbandaka in 1996 employed
CATI to interview 15 case-patients and 45 controls; contaminated peanut
butter was implicated (2). Foodborne disease
outbreaks are often geographically widespread and suited to using CATI.
Australian health authorities investigate ≈100 outbreaks of foodborne
disease each year, with 3–4 using CATI-based case-control studies. Some
jurisdictions investigate outbreaks by using CATI interviews of controls
sampled from a bank of potential study participants (3).
Potential study participants are recruited at the conclusion of rolling
risk factor survey interviews, similar to the Behavioral Risk Factor Surveillance
System.
A "control bank" allows investigators to rapidly obtain contact
details for appropriately matched controls because age and sex of all
household members are recorded in a database. Using control banks with
CATI allows completion of studies quicker than CATI or traditional methods
alone (4). South Australia has used CATI during
11 case-control studies of salmonellosis, legionellosis, Q fever, campylobacteriosis,
Shiga toxin–producing Escherichia coli, and cryptosporidiosis (http://www.dh.sa.gov.au/pehs/notifiable-diseases-summary/current-outbreak-table.htm).
During an Australian CATI survey about gastroenteritis, 5,123 (84%) of
6,087 households agreed to be in a control bank (5).
This bank of 14,024 potential controls was used in 4 case-control studies
of sporadic salmonellosis and campylobacteriosis. This system avoided
randomly dialing thousands of households to enroll controls in young age
groups. The control bank was used for 3 years after initial collection,
although many jurisdictions update banks annually.
Investigators may find CATI useful, although it can be costly and introduce
biases (4). Programming questionnaires can delay
investigations, which makes paper-based collection better in small outbreaks
(4). CATI cannot be used in areas where a small
proportion of the population has telephones. Despite limitations, CATI,
when combined with control banks, may improve outbreak investigations.
Martyn Kirk,*
Ingrid Tribe,† Rod Givney,† Jane Raupach,† and Russell Stafford‡
*OzFoodNet, Canberra, Australian Capital Territory, Australia; †Communicable
Disease Control Branch, Adelaide, South Australia, Australia; and ‡OzFoodNet,
Brisbane, Queensland, Australia
Suggested citation
for this article:
Kirk M, Tribe I, Givney
R, Raupach J, Stafford R. Computer-assisted telephone interview techniques
[letter]. Emerg Infect Dis [serial on the Internet]. Apr 2006 [date
cited]. Available from http://www.cdc.gov/ncidod/EID/vol12no04/05-0756_05-1583.htm
References
- Fox LM, Ocfemia MCB, Hunt DC, Blackburn BG, Neises
D, Kent WK, et al. Emergency
survey methods in acute cryptosporidiosis outbreak. Emerg Infect
Dis. 2005;12:729–31.
- Scheil W, Cameron S, Dalton C, Murray C, Wilson D. A
South Australian Salmonella Mbandaka outbreak investigation using
a database to select controls. Aust N Z J Public Health. 1998;22:536–9.
- Kenny B, Hall R, Cameron S. Consumer
attitudes and behaviours—key risk factors in an outbreak of Salmonella
typhimurium phage type 12 infection sourced to chicken nuggets.
Aust N Z J Public Health. 1999;23:164–7.
- Hope K, Dalton C, Beers Deeble M, Unicomb L. Biases and efficiencies
associated with two different control sources in a case-control study
of Salmonella typhimurium phage type 12 infection. Australas
Epidemiol. 2005;12:2–6.
- Hall G, Kirk M, Ashbolt R, Stafford RJ, Lalor K OzFoodNet Working
Group. Frequency
of infectious gastrointestinal illness in Australia, 2002: regional,
seasonal and demographic variation. Epidemiol Infect. 2006;134:111–8.
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In response: We appreciate the comments of Martyn
Kirk and colleagues, who describe their experience using computer-assisted
telephone interview (CATI) techniques in Australia with geographically
widespread foodborne outbreaks (1). The intent
of our article was to illustrate 1 example of the use of the CATI infrastructure
in investigating a large communitywide cryptosporidiosis outbreak (2);
yet we recognize the applicability of this infrastructure to multiple
acute infectious disease outbreak scenarios.
In our article, we comment that the use of existing CATI systems, like
the Behavioral Risk Factor Surveillance System (BRFSS), can provide a
practical means for obtaining controls in case-control studies, and the
letter by Kirk and colleagues describes their use of the CATI infrastructure
to create a "control bank" for acute infectious disease outbreak
investigations. This control bank includes participants of longitudinal
risk factor surveys, like BRFSS, who are subsequently recruited as controls
for outbreak investigations. We acknowledge that a "bank" of
these readily accessible controls could permit more rapid recruitment
of participants in numerous age strata and obviate the need for extensive
random digit dialing to recruit an adequate age-matched control population
in many investigations. Nevertheless, in most epidemiologic investigations,
controls need to be selected from the same geographic area as the case-patients,
and even in large telephone surveys, the number of respondents in any
given region can be small. This would make it difficult to recruit enough
controls within the small areas affected by most outbreaks, particularly
within specific age strata. A control bank may therefore be more practical
for use in large communitywide outbreaks, outbreaks that occur over large
regions (i.e., an entire state), or in densely populated areas. Additionally,
the lengthy start-up time required for questionnaire programming with
a CATI system also supports the view that the CATI method may be maximally
applicable in large-scale investigations.
LeAnne M. Fox,*
D. Charles Hunt,†‡ and Michael J. Beach*
*Centers for Disease Control and Prevention, Atlanta, Georgia, USA; †Kansas
Department of Health and Environment, Topeka, Kansas, USA, and ‡University
of Kansas Medical Center, Kansas City, Kansas, USA
Suggested citation
for this article
Fox LM, Hunt DC, Beach MJ. Computer-assisted telephone interview techniques
[response to letter]. Emerg Infect Dis [serial on the Internet]. 2006
Apr [date cited]. Available from http://www.cdc.gov/ncidod/EID/vol12no04/05-0756_05-1583.htm
References
- Kirk M, Tribe I, Givney R, Raupach J, Stafford R.
Computer-assisted telephone interview techniques. Emerg Infect Dis.
2006;12:697.
- Fox LM, Ocfemia MCB, Hunt DC, Blackburn BG, Neises D, Kent WK, et
al. Emergency
survey methods in acute cryptosporidiosis outbreak. Emerg Infect
Dis. 2005;11:729–31.
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