Discussion
cancer
CANCER, DISEASE, RECRUITMENT, SECONDARY, DISEASES
All five categories of influences proved to increase intention to participate with an adjusted OR > 1. Less than half of the participants indicated awareness of the influences, and not indicating awareness was associated with an increased intention to participate. For those who indicated a general awareness of influences, there was no statistically significant difference in intention to participate between those who correctly and those who incorrectly located the influences.A strength of this study is the randomized design where blinding of the interviewers was broken only after recruitment and thereby eliminating possible confounding. The interviews were conducted in consistence with a structured guide that addressed potential biases associated with breaking the blinding. Another potential strength is using an unknown, fictitious disease as cytoliosis eliminating fears and preconceptions associated with, e.g., cancer and well-known life-threatening diseases that could overestimate the intention to participate across all pamphlets. Our primary outcome was calculated as intention to participate, which we consider a strength because the intention to participate is regarded as a valid outcome of informed choice regarding cancer screening participation.A potential limitation of the present study is the risk of an interviewer’s effect on participants who might strive to answer what they believe is confirming the hypothesis of the researchers. This was addressed during the interviews through the structured interview guide.The results of the secondary outcomes should be interpreted with caution. Since the secondary outcomes are measured after the participants indicate their intention to participate, it may affect their response as to whether the pamphlet was trying to direct their choice. We hypothesize that the participants who intended to participate might be more reluctant to admit that they have been potentially influenced. This would understate the measured awareness in the groups with the highest intention to participate.Another limitation could be that the external validity of the study is limited due to cytoliosis being a fictitious disease. This might explain why pamphlet (D) (pre-booked appointments) has a relatively low effect size (adjusted OR 1.15) since participants could not relate to opting out of a ‘false’ screening programme. This could explain the discrepancy with a different study that found that the impact of pre-booked appointments compared to mailed reminders almost doubled participation within 6 months (risk ratio 1.9, 95% CI: 1.5–2.3).Before and after adjustment all six pamphlets proved an OR >1. We hypothesize that the statistically insignificant ORs might prove significant in a larger population. Regardless, decision-makers should take into consideration that a slightly positive OR can translate to great numbers of influenced participants in screening populations.Not indicating awareness of being influenced is associated with a stronger intention to participate. Citizens who are less alert to attempts at influencing their choices might therefore enrol in a screening programme because of being influenced rather than being convinced by unbiased information. These results beg consideration and discussion of the use of different types of influences applied to increase the participation rate in cancer screening programmes. The potential harms of participating in cancer screening programmes can be severe and substantial, and the intended effect of increasing the participation rate using influences must be carefully weighed against the unintended effect of potentially bypassing the participants’ informed choice. This indicates a need for alternative ways of appraising cancer screening programmes than by participation rate. One such alternative could be the rate of informed decisions by potential screening participants. However, appraising screening programmes by the rate of informed choice introduces new problems. Citizens might feel distressed trying to comprehend the many consequences, benefits and harms of the offered programmes.For future research, it is relevant to investigate the potential negative effects of using the influences. An example of such a negative effect is weakened trust in healthcare authorities.Informational material is not the only aspect of decision-making, and this study does not examine external reasons for the participants’ choices, e.g. society’s (health) culture, one’s own and society’s general attitudes to health interventions, sense of duty, behaviour and opinions of relatives, barriers to intention and actual behaviour, health professionals’ financial incentives to increase screening uptake, etc. The impact of informational material on actual choice may be limited.In conclusion, the considerable effect of the influences that are further enhanced by non-awareness suggests that the application of such influences should be carefully considered for interventions where participation on an informed basis is intended. Further research about the potential negative effects of influences is warranted, i.e. weakened trust in health authorities.