Time to Screening in the Systems of Support to Increase Colorectal Cancer Screening Trial.

Publication Type:

Journal Article


Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology (2014)


2014, June 2014, Public Health Sciences Division


Understanding how interventions affect time to completion of colorectal cancer (CRC) screening might assist in planning and delivering population-based screening interventions. The Systems of Support to Increase CRC Screening (SOS) study was conducted between 2008 and 2011 at 21 primary care medical centers in Western Washington. Participants in the study, aged 50-73 years, were eligible if they were enrolled in Group Health and were due for CRC screening. 4,675 recruited participants were randomized to usual care (UC) or one of three interventions with incremental levels of systems of support for completion of CRC screening. We conducted time to screening analyses of the SOS data in year 1 and year 2. We investigated whether these effects were time-varying. For year 1, the intervention effects on the time to completion of CRC screening were the strongest during the first two post-randomization months then decreased, with no significant effect after the 5th month. For year 2, the intervention effects on the time to CRC screening increased from the 1st to the 3rd month and then decreased, with no significant effect after the 5th month. Hence, each of the interventions to increase CRC screening had its greatest effect within the first 3 months after being offered to participants. Future studies should test whether booster interventions offered later could increase screening rate among those who remain unscreened. Additional research is needed to develop intervention strategies for CRC screening that focus on sustained behavior over time.