Personal invitations for fecal occult blood tests (nowadays mostly fecal immunochemical tests) are increasingly used to raise their usage for colorectal cancer screening. However, there is a large heterogeneity in applied invitation schemes. We aimed to review evidence for the effectiveness of various invitation schemes. The main outcome was the fecal occult blood test usage rate. A systematic search was performed in Medline and Web of Science (up to 9 July 2020). Randomized controlled trials or cluster-randomized controlled trials were eligible, which reported on general invitations for fecal occult blood test-based colorectal cancer screening sent to the general population at average colorectal cancer risk. (PROSPERO 2020 CRD42020169409). Overall, 34 studies were included. Invitations with an attached, i.e., mailed fecal occult blood test consistently increased test usage by 4-19.7% points, compared to other methods of test provision. Likewise, the introduction of advance notification consistently led to a higher usage rate, with an increase of 3.3-10.8% points. Reminders showed positive but varying effects by method. With an increase of 8.5-15.8% points, letter or email reminders were more effective than reminders by phone call or text message (0.6-6.5% points). Inconsistent results were found for financial incentives ((-8.4)-20% points) and for added or changed invitation material ((-3.5)-11.8% points). With 3.5-24.7% points, the strongest increases in use were achieved by multifaceted invitation, implementing multiple components. Any invitation scheme was superior over no invitation. Advance notification, mailing of fecal occult blood test, and reminders were consistently shown to have major, complementary potential to increase participation in fecal occult blood test-based colorectal cancer screening settings.
Keywords: colorectal cancer; early detection; fecal occult blood tests; invitation; screening.