Which Test Is Best? A Cluster-Randomized Controlled Trial of a Risk Calculator and Recommendations on Colorectal Cancer Screening Behaviour in General Practice.

Introduction: This cluster-randomized controlled trial aimed to assess the effect of the "Which test is best?" tool on risk-appropriate screening (RAS) and colorectal cancer (CRC) screening uptake.

Methods: General practices in Sydney and Melbourne, Australia, and a random sub-sample of 460 patients (aged 25-74 years) per practice were invited by post. Clusters were computer randomized independently of the researchers to an online CRC risk calculator with risk-based recommendations versus usual care. Primary and secondary outcomes were RAS and screening uptake via self-reported 5-year screening behaviour after 12 months follow-up. The usual care group (UCG) also self-reported 5-year CRC screening behaviour at 12 month post-randomization.

Results: Fifty-six practices were randomized (27 to the intervention and 29 to the control, 55 practices participated) with 818 intervention and 677 controls completing the primary outcome measure. The intervention significantly increased RAS in high-risk participants compared with UCG (80.0% vs. 64.0%, respectively; OR = 3.14, 95% CI: 1.25-7.96) but not in average-risk (44.9% vs. 49.5%, respectively; OR = 0.97, 95% CI: 0.99-1.12) or moderate-risk individuals (67.9% vs. 81.1%, respectively; OR = 0.40, 95% CI: 0.12-1.33). Faecal occult blood testing uptake over 12 months was increased compared with the UCG (24.9% vs. 15.1%; adjusted OR = 1.66, 95% CI: 1.24-2.22), and there was a non-significant increase in colonoscopies during the same period (16.6% vs. 12.2%; adjusted OR = 1.42, 95% CI: 0.97-2.08).

Conclusion: An online CRC risk calculator with risk-based screening recommendations increased RAS in high-risk participants and improved screening uptake overall within a 12-month follow-up period. Such tools may be useful for facilitating the uptake of risk-based screening guidelines.