Colorectal cancer (CRC) is the second leading cause of cancer deaths in the U.S. (1
). Because early detection and removal of pre-cancerous polyps may contribute to decreased incidence of CRC (2
), several authoritative groups recommend CRC screening for average-risk individuals age 50 and older (1
). However, screening rates are suboptimal (≤ 50%) (5
Sociodemographic, health status, and psychosocial factors have been associated with CRC screening (7
). Of these, psychosocial variables are more amenable to change through behavioral interventions designed to increase CRC screening uptake. Support exists for several psychosocial correlates and predictors of CRC screening (11
); however, scant attention has been paid to understanding the mechanisms underlying these associations.
Greater understanding of the longitudinal associations and causal mechanisms linking these determinants to CRC screening is needed to inform the design of effective interventions. Such mechanisms may be uncovered by exploring potential mediators and moderators. Mediators such as self-efficacy and intention may be hypothesized precursors of behavior change, and may help explain the mechanism by which distal predictors (i.e., perceived susceptibility) influence behavioral outcomes. Moderators interact with predictor variables to impact the outcome variable (i.e., direction or magnitude of effect) and specify the conditions under which the effect occurs.
Perceived susceptibility, a psychosocial construct in several health behavior theories, has been posited as an important motivating force behind precautionary behavior. However, researchers disagree on the mechanism by which perceived susceptibility affects behavior (12
). One view is that perceived susceptibility is one of many direct causes of behavior (hypothesis 1 in the current study). The Health Belief Model reflects this view and includes only direct effects of model variables on behavioral outcomes (12
). Tests of alternative models to the Health Belief Model have found support for perceived benefits as mediating the effect of perceived susceptibility on health behaviors (15
), thus suggesting that perceived susceptibility is a distal cause of behavior that operates through its influence on more proximal determinants (hypothesis 2 in the current study). Fishbein’s integrated model suggests the view that perceived susceptibility is expected to affect intention and behavior, but only indirectly through its effect on mediating variables such as attitudes, subjective norms, and self-efficacy (17
). Empirical research to date has been limited by the use of cross-sectional data to test mediation models of perceived susceptibility and most studies have focused on perceived benefits as a mediator (15
An alternative view of the relation between perceived susceptibility and behavior is that initial status of perceived susceptibility moderates the change in other psychosocial factors that influence subsequent intention and behavior (hypothesis 3 in the current study). The Precaution Adoption Process Model suggests that awareness and perceived susceptibility to a health risk are necessary but not sufficient for action (19
), and that determinants of behavior change vary by stage (20
). Individuals who are unengaged with a preventive behavior (Precaution Adoption Process Model stage 2) need to accept the risk as personally relevant or salient in order to move forward and decide to act (Precaution Adoption Process Model stage 5) (13
). In this case, a threshold level of perceived susceptibility must be reached before one will attend to action recommendations, formulate an attitude, and ultimately increase active coping behaviors and behavior change. Then, once a decision to act is made, any barriers to performing the behavior need to be overcome. Likewise, some studies have found lower perceived susceptibility among contemplators compared with people in preparation or action stages of behavioral change (21
These health behavior theories provide different models of the structural and psychological processes that are hypothesized to influence behavior. Interventions depend on clearly delineated and empirically supported theories of behavior change; therefore, attention to theory evaluation is needed (23
). Because perceived susceptibility is an important construct in many health behavior theories, and because its effect on behavior is uncertain, understanding the relative influence of perceived susceptibility and the process by which it influences behavior is important and may improve future cancer screening interventions.
The purpose of this secondary data analysis was to explore multiple hypotheses (1 to 3 above) suggested by health behavior change models about the role of perceived susceptibility to CRC on CRC screening intention and behavior at different points within a longitudinal model. We examined three pathways of influence that correspond to direct effect, mediation, and moderation hypotheses based on the theories reviewed above. Results will inform the conceptualization of the role of perceived susceptibility in models predicting intentions and behaviors.