Smith, SG;
(2014)
Using ‘gist-based’ information to reduce inequalities and improve cancer screening uptake.
Doctoral thesis (PhD), UCL (University College London).
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Abstract
Colorectal cancer (CRC) is the second most common cause of cancer death in the UK. Screening is key to promoting early diagnosis and thereby improving survival. The English NHS Bowel Cancer Screening Programme (BCSP) invites adults aged 60-69 to complete a home-based Faecal Occult Blood test (FOBt) kit every 2 years. Routinely collected data indicate uptake of only 54% for the first invitation; varying from 35% in the most deprived quintile of residential areas to 61% in the least deprived quintile. Evidently, the full benefits of CRC screening are not being realised and inequalities in CRC outcomes may increase. Evidence from a number of sources indicates less awareness of CRC, and less recognition of the benefits of screening, in lower SES groups. It is therefore crucial that the screening information booklet mailed with the test enables people of all levels of health literacy to make an informed decision about participating in the BCSP. This thesis describes the development and testing of a health communication intervention that aims to reduce inequalities in uptake. Study 1 used the ‘think-aloud’ method to examine responses to the existing information booklet in order to identify barriers to comprehension. The process of designing a supplementary leaflet to facilitate ‘gist-based’ processing is described. Gist is defined as the qualitative representation of concepts, and gist-based processing is the preference for evaluating information in its simplest form. Performance-based user-testing was used to optimise the content, design and layout of the gist leaflet (study 2). The communicative effectiveness of the leaflet was tested in study 3, which was a community-based randomised controlled trial (registration number: ISRCTN62215021) in which adults approaching the screening age were randomised to be sent standard screening information (control) or standard information plus the gist leaflet (intervention). Findings from 964 respondents showed that the gist leaflet was considered to be readable and useful and did not cause additional worry about CRC. Screening intention and perceived risk were unaffected by the gist leaflet, however knowledge was significantly higher among the intervention group. Study 4 was a national, cluster randomised trial (registration number: ISRCTN74121020) nested in the existing NHS BCSP (n=163,566). Adults who were 5 being sent a screening invitation were randomised to receive the standard information or standard information plus the gist leaflet. Randomisation was by day of mailing and stratified by screening hub. The gist leaflet had no effect on the socioeconomic gradient in screening uptake and no effect on screening uptake overall. Among a sub-sample of people being invited for the first time, a small but significant difference in screening uptake was seen in the intervention group. This effect was particularly apparent among men and older people. Despite the small effects of the gist intervention on screening uptake among specific sub-groups, the provision of supplementary gist-based information in this context is unlikely to reduce the socioeconomic gradient in CRC screening uptake. Implications for the NHS BCSP and future research are discussed.
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