Neighborhood socioeconomic status and the effectiveness of colorectal cancer screening outreach with mailed fecal immunochemical tests within a safety net healthcare system in San Francisco, CA: A subgroup analysis of a randomized controlled trial

Abstract

Neighborhood context shapes opportunities and barriers for residents to access healthcare and cancer screening. Neighborhood socioeconomic status (nSES) is associated with disparities in colorectal cancer (CRC) screening, but the extent to which the effectiveness of specific screening interventions vary by nSES has not been studied. The original trial conducted in San Francisco, CA from 2016 to 2017 randomly assigned patients eligible for CRC screening either to a multicomponent intervention including advanced notification, mailed fecal immunochemical test (FIT) kits and reminders or to a control group receiving usual care. For the nSES analysis addresses for 9699 patients were geocoded and stratified by city-wide nSES quintile (Q1 lowest, Q5 highest) using an established index at the census tract level. Compared to usual care, the outreach intervention improved FIT test completion at one year (58.7% vs 38.4%; OR 2.32 [2.14, 2.52]) but its effectiveness did not vary substantially by nSES quintile (adjusted OR Q1 2.64 [2.30, 3.04]; Q2 2.43 [2.04, 2.90]; Q3 2.31 [1.84, 2.89]; Q4 2.47 [1.86, 3.28]; Q5 2.64 [1.83, 3.81]; Wald test for interaction p = 0.87). The implementation of mailed FIT outreach has the potential to increase CRC screening completion without leading to disparities in screening related to nSES (ClinicalTrials.gov NCT02613260).