The effectiveness and cost effectiveness of a screening programme may be strongly influenced by the participation rate not least because those who reject participation may do so due to reasons that are associated with a greater risk of disease [1,2]. However, if non-participation reflects rational behaviour based on full information about the costs and benefits of the screening programme, declining to participate may be welfare enhancing. In order to decipher whether the patterns of participation reflect societal optimum, or whether efforts should be made to increase participation, it is important to gain knowledge of why individuals choose to accept or reject screening invitations.
The literature on what determines attendance rates and the individual participation decision appears to be limited and generally focused on cancer screening. In relation to colorectal cancer it has been shown that compensation may increase participation rates and that the propensity to participate is associated with socio-demographics, genetic predisposition, travel expenses, and subjective health status among others [3]. Another study in this disease area demonstrated that adoption of health protective behaviours is associated with a higher attendance whereas anxiety represents a strong barrier to participation [4]. Finally it has been suggested that low priority for screening is an important determinant for non-attendance [5].
Screening for non-cancer-related diseases might be affected by different motives, in particular if there is less physical discomfort and/or emotional distress associated with the test but also if structural issues such as information, infrastructure, and local provision vary. An early study by Bryan et al., who surveyed individuals invited for abdominal aortic aneurysm screening suggested that private costs might play an important role for the participation decision [6].
Neoclassical economic theory predicts that the individual will choose to participate in screening if the expected utility the individual gets from participation is greater than the expected disutility (i.e. if the benefits outweigh the costs) [7]. The benefits of screening relate to the reduction in uncertainty about future disease as well as the actual gain in health-related quality and length of life flowing from early detection of eventual disease. It has also been proposed that individuals gain utility from participation per se [8]. This could be due to receiving general information or minimising later regret, factors that are unrelated to the effectiveness of the programme. The personal costs of participation include the emotional distress associated with the articulation of the disease risk and prognosis, (expected) disutility of undergoing the test, plus the effort and expenses associated with travelling to and attending the test session, among others.
The perceived net benefit to the individual of engaging in screening depends on his preferences (i.e. how he weighs and values the arguments for and against participation). There is a history of measuring the strength of preferences for screening programmes by individuals’ stated willingness to pay (WTP) [9 ⇓–11]. This value is typically elicited by setting up a valuation task in a laboratory setting. The advantage of this approach is that valuations can be elicited for goods or services that are not sold on a market (or for which there is insufficient price variation). Furthermore, it allows for the presentation of information that may not be available on a “real” market. Valuations based on stated preferences thus, in some cases, may be more accurate than valuations based on revealed preferences if they are based on more information. The disadvantage of stated preference methods is that valuations may suffer from hypothetical bias, although this can be relieved if individuals are presented with realistic and relevant valuation tasks.
This paper focuses on screening for cardiovascular disease, which seems to be an under-informed area in terms of the determinants of the participation decision and thus what can be initiated to improve the participation rate and in turn the effectiveness of screening programmes. A particular strength of the present study design is that individuals are surveyed after their behaviour has been observed, and that both participants and non-participants are surveyed about their decision uncertainty and preferences for screening. That the participants have made an actual choice prior to the survey is thought to minimise hypothetical bias as the questions posed in the stated preference survey are strongly linked to the actual choice scenario.
The objective of this study was to compare participants’ and non-participants’ motives for the attendance decision as well as their overall preferences for participation in cardiovascular disease screening.