Online market research panel members as controls in case–control studies to investigate gastrointestinal disease outbreaks: early experiences and lessons learnt from the UK

Abstract

Established methods of recruiting population controls for case–control studies to investigate gastrointestinal disease outbreaks can be time consuming, resulting in delays in identifying the source or vehicle of infection. After an initial evaluation of using online market research panel members as controls in a case–control study to investigate a Salmonella outbreak in 2013, this method was applied in four further studies in the UK between 2014 and 2016. We used data from all five studies and interviews with members of each outbreak control team and market research panel provider to review operational issues, evaluate risk of bias in this approach and consider methods to reduce confounding and bias. The investigators of each outbreak reported likely time and cost savings from using market research controls. There were systematic differences between case and control groups in some studies but no evidence that conclusions on the likely source or vehicle of infection were incorrect. Potential selection biases introduced by using this sampling frame and the low response rate are unclear. Methods that might reduce confounding and some bias should be balanced with concerns for overmatching. Further evaluation of this approach using comparisons with traditional methods and population-based exposure survey data is recommended.

Retrospective assessment of rapid outbreak investigation for gastrointestinal diseases using only cases and background exposure data

“…A number of methods have been proposed in the past that include comparing cases against different types of information for ‘controls’ such as market research panels using online questionnaires [31, 32], case-case study designs [14, 33, 34] and a simulation-type approach for generating ‘control’ information [35]. An attempt has been made in the Netherlands to collect background population exposure via an infectious disease repeated electronic survey that can then be used in outbreak investigations [36].…”

Are food exposures obtained through commercial market panels representative of the general population? Implications for outbreak investigations

“…This paper presents the results of a novel comparison between food exposure data from market panel recruited controls and an established population survey. This is an important comparison given the increasing use of these approaches in outbreak investigation in the UK and internationally [ 17 ]. We found that when adjusted for socio-demographic factors, there were statistically significant differences in the percentage of participants exposed to 90% of foods between both panels and the reference data; however, in the context of large ORs typically associated with foodborne exposures leading to outbreaks the difference was practically important (a greater than threefold difference in odds of reported exposure) for only 11% of foods.…”

“…Issues previously identified with using market research panels include panel responsiveness, socio-demographic representativeness, careless responses, overlap between panel membership and biases due to recruitment [ 29 , 30 ], though market research companies attempt to address these issues through routine practice [ 17 ]. One of the key benefits of this approach, however, is the efficiency with which large numbers of controls can be rapidly recruited with little public health resource [ 12 ].…”

“…Although the logistical issues associated with using these controls have been reviewed [ 17 ], there has thus far been no systematic assessment of the quality of food exposure information obtained from these market panel recruited controls compared with a gold standard. Without this information there is a question as to whether these controls are comparable with the general population and thus representative of the population at risk.…”

Online market research panel members as controls in case–control studies to investigate gastrointestinal disease outbreaks: early experiences and lessons learnt from the UK – ERRATUM

“…Online market research panel members as controls in case-control studies to investigate gastrointestinal disease outbreaks: early experiences and lessons learnt from the UK -ERRATUM P. Mook One of the authors of the above article (Mook, P, et al (2018)), affiliations were incorrectly identified in the original article. They have been correctly listed below:…”