Behavioral mediators of colorectal cancer screening in a randomized controlled intervention trial
Introduction
Numerous factors influence health behaviors and a comprehensive theoretical model can provide a roadmap for systematically addressing determinants of health behavior in an intervention trial (Bastani et al., 2010). In turn, a controlled trial of a theory-based intervention can inform the underlying theory by shedding light on pathways by which behavioral change was achieved (Rothman, 2004, Anderson et al., 2010). Understanding mediators for behavioral change can help us to optimize intervention strategies by focusing on the factors that are most important in achieving behavior change (MacKinnon and Luecken, 2008, Mackinnon and Fairchild, 2009). Many theory-based interventions to increase cancer screening have been reported in the literature (Wardle et al., 2003, Lipkus et al., 2005, Marcus et al., 2005, Tu et al., 2006), but to our knowledge this is one of the first analyses that examines the pathways through which change was achieved.
Our prior work demonstrated the effectiveness of an intervention in increasing colorectal cancer (CRC) screening among Filipino Americans in a randomized trial. Participants randomized to either of the two intervention arms were significantly more likely to report screening at follow-up than participants assigned to the control group (odds ratios 4.9 and 3.7 compared with control, both p < .001 (Maxwell et al., 2010). In this report, we assess the impact of this intervention on behavioral constructs, including awareness of CRC screening, patient-provider communication about CRC screening, health beliefs and barriers to FOBT and sigmoidoscopy/colonoscopy. We examine these variables as mediators of the desired change in CRC screening behavior. Identifying the underlying mechanisms through which behavior change is enacted is important for adaptation of evidence-based interventions for wide dissemination and for informing the development of future cancer screening behavioral interventions.
Section snippets
Randomized trial to increase CRC screening among Filipino Americans
In collaboration with 45 Filipino American community-based organizations and churches in Los Angeles County, we recruited 548 Filipino Americans 50–70 years of age who were non-adherent to CRC screening guidelines: no fecal occult blood test (FOBT) during the past 12 months, no colonoscopy during the past 10 years and no sigmoidoscopy during the past 5 years. Following a baseline interview, participants were organized into small groups of 6–10 subjects in a manner that capitalized on existing bonds
Study participant characteristics
The mean age of the sample was 59 years, average years lived in the United States was 19 years, and 67% of the sample was female (Table 1). More than two thirds were married and had a college education and slightly less than two thirds had an annual income less than $50,000. Most considered themselves more Filipino than American (61%) or equally Filipino and American (35%) and only 18% spoke mainly Filipino with their friends. Although most had health insurance (72%) and a regular doctor (82%),
Discussion
After having demonstrated the effectiveness of an intervention in increasing CRC screening among Filipino Americans, this report examines behavioral mediators of change in screening behavior. The most important mediator that emerged in our analysis was patient-provider communication about CRC testing. Many studies have demonstrated that patient-provider communication and specifically a provider recommendation is strongly associated with cancer screening (Maxwell et al., 1997, Taylor et al., 2003
Conclusions
Consistent with the Health Behavior Framework, awareness of CRC screening and patient-provider communication about CRC screening mediated increased screening in this randomized trial in the Filipino American community. Examining the roles of these and other constructs as potential mediators in different intervention trials in different settings and populations may help in the identification of constructs that need to be targeted to optimize interventions to increase screening.
Conflict of interest statement
The authors declare that there are no conflicts of interest.
Acknowledgments
This work was supported by grant RSGT-04-210-01-CPPB from the American Cancer Society. CMC was supported by NIH/NCI grant P30 CA 16042. We would like to thank the members of the Filipino American community who participated in this study and the research staff, Cynthia Antonio, MPH and Gabriel M. Garcia, Ph.D.
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