Behavioral mediators of colorectal cancer screening in a randomized controlled intervention trial

Understanding mediators for behavioral change is important for the optimization of intervention strategies. This report examines mediators of change in the context of a randomized controlled intervention trial (Los Angeles, 2004-2009) that successfully increased colorectal cancer (CRC) screening among Filipino Americans.The intervention, based on the Health Behavior Framework, targeted knowledge/awareness of CRC screening, communication with health care provider, health beliefs, social support and barriers to CRC screening. Health Behavior Framework variables were assessed at baseline and 6-month follow-up (N=432). Variables targeted for change were tested as potential mediators of the primary outcome, self-reported receipt of CRC screening during the follow-up period, which was previously found to have increased significantly among intervention participants.Consistent with the Health Behavior Framework, knowledge/awareness of CRC screening and patient-provider communication mediated receipt of screening. Increase in knowledge/awareness of CRC screening accounted for 13% (95% confidence interval 2%-24%) of the total intervention effect size, while patient-provider communication accounted for 20% (5%-36%). Combined, these two variables accounted for 28% (10%-46%) of the total effect size.Examining the roles of potential mediators in intervention trials may help identify constructs to target in order to enhance the effectiveness of interventions to increase screening.