The impact of information about different absolute benefits and harms on intention to participate in colorectal cancer screening: A think-aloud study and online randomised experiment

Abstract

Background There is considerable heterogeneity in individuals’ risk of disease and thus the absolute benefits and harms of population-wide screening programmes. Using colorectal cancer (CRC) screening as an exemplar, we explored how people make decisions about screening when presented with information about absolute benefits and harms, and how those preferences vary with baseline risk, between screening tests and between individuals. Method We conducted two linked studies with members of the public: a think-aloud study exploring decision making in-depth and an online randomised experiment quantifying preferences. In both, participants completed a web-based survey including information about three screening tests (colonoscopy, sigmoidoscopy, and faecal immunochemical testing) and then up to nine scenarios comparing screening to no screening for three levels of baseline risk (1%, 3% and 5% over 15 years) and the three screening tests. Participants reported, after each scenario, whether they would opt for screening (yes/no). Results Of the 20 participants in the think-aloud study 13 did not consider absolute benefits or harms when making decisions concerning CRC screening. In the online experiment (n = 978), 60% expressed intention to attend at 1% risk of CRC, 70% at 3% and 77% at 5%, with no differences between screening tests. At an individual level, 535 (54.7%) would attend at all three risk levels and 178 (18.2%) at none. The 27% whose intention varied by baseline risk were more likely to be younger, without a family history of CRC, and without a prior history of screening. Conclusions Most people in our population were not influenced by the range of absolute benefits and harms associated with CRC screening presented. For an appreciable minority, however, magnitude of benefit was important.

A community jury study exploring the public acceptability of using risk stratification to determine eligibility for cancer screening

“…This is consistent with results from a survey about the intention to attend bowel cancer screening, where most people were not influenced by the absolute benefits and harms presented. 33 In contrast to other studies, we did not observe a focus on the negative implications of a high-risk classification (such as distress, potential pressure for lifestyle changes or the burden of being highrisk for multiple cancer types). 28,34 Reduction in the potential harms of screening for those at low risk was also not a consideration, emphasizing that this may be of greater concern for researchers and clinicians than the public.…”

“…While evidence was necessary to support their decision, risk stratification was viewed favourably if there was any benefit. This is consistent with results from a survey about the intention to attend bowel cancer screening, where most people were not influenced by the absolute benefits and harms presented 33 …”

“…This is consistent with results from a survey about the intention to attend bowel cancer screening, where most people were not influenced by the absolute benefits and harms presented. 33 …”

Behavioural Challenges Associated With Risk-Adapted Cancer Screening

“…14 In addition, a majority of participants asked about willingness to take up colorectal screening stated that they would accept the offer if at 1%, 3%, or 5% 15-year risk, although participants were more likely to be willing to take up an offer if at higher risks. 25 There are also encouraging findings to suggest that receiving information on risk status does not cause large negative reactions. For example, Emmons et al 26 found that 33% of participants reported lower worry after completing colorectal cancer risk assessment and Trevena et al 27 found no difference in anxiety between targeted colorectal cancer risk information and generic information on colorectal cancer screening.…”

“… 14 In addition, a majority of participants asked about willingness to take up colorectal screening stated that they would accept the offer if at 1%, 3%, or 5% 15-year risk, although participants were more likely to be willing to take up an offer if at higher risks. 25 …”