Background: Colorectal cancer (CRC) screening saves lives, but is underutilized, particularly among individuals with low socioeconomic position and Hispanic ethnicity. Our aim was to assess effectiveness of a regional mailed fecal immunochemical test (FIT) intervention at year 1 from a cluster randomized trial among southern California community health center (CHC) patients not up-to-date with colorectal cancer (CRC) screening.
Methods: The San Diego Accelerating Colorectal Cancer Screening and Follow-up through Implementation Science (ACCSIS) project represents a partnership testing regional implementation of a Hub-and-Spoke model for increasing CRC screening and follow-up. The “hub” is a non-academic, non-profit organization. The “spokes” are 3 CHC systems that combined oversee over 66 clinic sites in San Diego and Riverside Counties. Using a cluster-randomized trial design, 9 clinics were randomized to intervention and 16 to usual care. The intervention included an invitation letter, a mailed FIT with completion instructions, and phone and text-based reminders. Year 1 intervention impact (of 3 years of planned intervention) was assessed as proportion completing screening among individuals not up-to-date at baseline, comparing intervention and non-intervention clinics using generalized estimating equation analyses and accounting for intra-cluster variation, specifying clinic as a clustering variable.
Results: Among participating clinics, 27,820 patients who were age-eligible and not up-to-date with CRC screening at the time of randomization were included for analysis. Approximately 59% of participants were female and 60% were Hispanic. Over the year 1 observation period, screening completion proportion was 11.2 (95% CI, 3.9-18.5) percentage points (ppt) higher in the intervention (34.1%) than usual care (22.9%) group. Variation in differences between intervention and non-intervention clinics by subgroups were observed by gender (12.2 ppt for females; 95% CI, 4.6-19.8 and 8.6 ppt for males; 95% CI, 1.0-16.2), and by racial and ethnic group (13.6 ppt for Hispanic individuals, 95% CI, 4.8-22.4; 11.0 ppt for Non-Hispanic White individuals, 95% CI, 4.7-17.3; 5.7 ppt for Black individuals, 95% CI, -3.1-14.5; 12.6 ppt for Asian individuals, 95% CI, 1.8-23.4; 17.8 ppt for Pacific Islander individuals, 95% CI, -2.8-38.4 Figure).
Conclusions: A regional mailed FIT outreach intervention was effective for increasing CRC screening rates across a broad array of CHC systems serving multiple populations at risk for non-participation in screening.

<b>Differences in proportion of patients up-to-date with CRC screening between intervention and non-intervention clinics, overall, and by sub-groups.</b> M, male; F, female; AI/AN, American Indian/Alaska Native; HPI; Native Hawaiian/Pacific Islander; NHW; non-Hispanic White

Differences in proportion of patients up-to-date with CRC screening between intervention and non-intervention clinics, overall, and by sub-groups. M, male; F, female; AI/AN, American Indian/Alaska Native; HPI; Native Hawaiian/Pacific Islander; NHW; non-Hispanic White

Sheila Castañeda

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