OBJECTIVES: Since 2004, the National Colorectal Cancer Screening Program has been annually conducting fecal occult blood test (FOBT) for aged 50 and older in South Korea. Person with FOBT-positive have recommend double contrast barium enema (DCBE) or colonoscopy as secondary screening. However, compliance to the secondary screening after FOBT was lower than expected. The purpose of this study is to identify the clinical factors associated with adherence to the secondary screening for colorectal cancer according to age in Korean National Cancer Screening Program (NCSP).

METHODS: We linked NCSP data and claims data from the National Health Insurance Service database to analyze adults aged over 50 years old who had positive results of FOBT in NCSP. Adherence groups were defined as those who underwent secondary screening within one year of receiving FOBT results.

RESULTS: From a total of 214,131 individuals identified with positive FOBT, 120,911 (56.5%) were in the compliance group and 93,220 (43.5%) in the non-compliance group. Our study population was divided into two groups based on age 65. The experience of positive FOBT within 1 year was highly associated with greater adherence to the secondary screening after FOBT (+) of NCSP (OR=2.97 in the younger group, OR=1.85 in the older group, both p<0.0001) than an experience of negative FOBT or no experience of FOBT in both age groups. Male, absent personal history of colonoscopy or DCBE, and high economic status were also associated with adherence to the secondary screening in both age groups. BMI was associated with adherence to the secondary screening only in the younger group. The type of health insurance and the presence of hemorrhagic and hematologic diseases did not affect the secondary screening adherence after FOBT (+) in the older group.

CONCLUSIONS: Based on these associated factors of this study, a support system or policy should be considered.