Effectiveness of Theory-based Outreach Using Mobile Health Technology in Colorectal Cancer Screening Uptake: a Randomized Controlled Trial

In Hong Kong, Colorectal cancer (CRC) ranked second in both cancer incidence and mortality, accounting for 16.7% of all new cancer cases and 14.6% of all cancer-related deaths in 2019. There was a staggering 2.5-fold increase in the number of newly diagnosed CRC cases from 1584 to 2019.

The fecal immunochemical test (FIT) helps reduce the incidence and mortality of CRC and is widely used for population-based CRC screening. The government-subsidized CRC screening program was launched in Hong Kong as a pilot in 2015 and fully implemented in 2020. The program was subsidized for asymptomatic Hong Kong residents, aged 50-75 years, to receive FIT screening every two years. A subsidized follow-up colonoscopy was offered for a positive FIT result. For a negative FIT result, the participant was advised to repeat the screening two years later.

Despite the subsidy and promotion, the uptake rate of the population-based colorectal cancer screening was low. Only 275,000 (~10%) underwent FIT screening under this program as of 31st December 2021. Efforts have been made to increase the rate. Outreach is the active dissemination of screening outside of the primary care setting, and it also includes mailing, texting, and calling to encourage scheduling of screening procedures.

It was technically infeasible to conduct fecal test outreach by mailing the test kits in Hong Kong because the government-subsidized colorectal cancer screening program required consultation with a primary care physician to assess the subjects' health condition, and their eligibility before distributing the fecal test kits. Similar to colonoscopy screening outreach, an alternative method is to provide contact information with primary care physicians located in the subject's preferred district via mobile messenger-based chatbots to arrange a consultation for FIT screening. Chatbots have already proven to be useful in increasing the intention to vaccinate against COVID-19.

Moreover, CRC screening uptake is highly associated with Health Belife Model (HBM) constructs and high risk perception of developing CRC is associated with higher screening uptake rate. HBM-based education and Trans-Theoretical Model (TTM)-based personalized risk assessment of CRC may increase the screening uptake rate by improving their knowledge of CRC screening (in terms of susceptivity, perceived benefits, and cues to actions) and informing subjects that they are at a relatively higher risk of developing CRC.