Online Questionnaires for Outbreak Investigations

To the Editor:

The online questionnaire has become a viable alternative in many research disciplines to paper-based questionnaires. However, it is still not a commonly used method for epidemiologic outbreak investigations. We compared an online questionnaire with a paper-based questionnaire for an outbreak investigation in the South Australian Department of Health.

In April 2010, we initiated a retrospective cohort investigation for a suspected gastroenteritis outbreak at a 3-day residential church camp (n = 89). Using a commercial online survey website, we constructed a standard cohort study questionnaire.

All listed attendees were invited by an e-mail to participate in the online questionnaire. It provided information about the suspected outbreak, instructions for survey completion, the survey link, and a unique personal identification code for each attendee. To ensure that all attendees were able to access the questionnaire, reminders were delivered in a variety of ways. After 1 week, a reminder e-mail was sent to nonresponders (n = 38). After 2 weeks, a reminder phone call was made (n = 18), during which the callers reiterated the importance of completing the survey even if the attendee was not ill, and an offer was made to administer the questionnaire by phone while staff directly entered the responses online (n = 2).

The online questionnaire Web site recorded the time and date on which each survey was finished and the number of partially and fully completed surveys. Data were downloaded directly into a Microsoft Excel spreadsheet, thus minimizing data entry and data cleaning. Data were transferred directly from the spreadsheet into STATA 10 (Statacorp, TX) for analysis.

Online questionnaire submission times were compared with the paper-based investigation submission times (each manually date stamped) from another recent South Australian outbreak investigation cohort study (also a multiday camp).

The online questionnaire had rapid and high response rate compared with traditional paper-based investigation techniques (Table). This method also reduced administrative time, costs, and data entry error. Online data were available immediately with no data entry required, compared with the additional steps of database development, and data entry necessary for a paper-based investigation. Initial analysis was able to begin just after the questionnaire launched, and 92% of all respondents had successfully completed the online questionnaire within 7 days (n = 68). This online method required approximately 24 fewer staff hours than a paper-based investigation of the same size.

TABLE: Comparison of Online and Paper-based Investigation Timeframes

Furthermore, timely questionnaire completion may strengthen the results of outbreak investigation through reduced recall bias. This is especially important in this multiday camp setting, because attendees were asked to recall several meals.

An important potential limitation when using online questionnaires, however, is an inability to safeguard confidentiality. We ensured confidentiality by not including any questions on identifying information in the questionnaire. Although access to the Internet for our cohort was high, care also must be taken to ensure no selection bias is created through the use of an online questionnaire where access is uncertain.¹

In selected circumstances, an online data collection method can make it possible to obtain higher quality information more rapidly, which can in turn facilitate timely public health action.

Amy Elizabeth Parry

Communicable Disease Control Branch

South Australian Department of Health

South AustraliaNational Centre for Epidemiology and Population Health

Australian National University

Canberra, Australia

[email protected]

David R. Johnson

Kellie Byron-Gray

Jane C. A. Raupach

Communicable Disease Control Branch

South Australian Department of Health

Adelaide, South Australia

Michelle McPherson

National Centre for Epidemiology and Population Health

Australian National University

Canberra, Australia