# Colorectal Cancer Screening Among People With Intellectual Disabilities

## TL;DR

People with intellectual disabilities in Denmark are less likely to participate in and complete colorectal cancer screening compared to those without disabilities, highlighting the need for tailored strategies to address these disparities.

## Contribution

This study provides empirical evidence of inequities in colorectal cancer screening participation and completion among people with intellectual disabilities.

## Key findings

- People with intellectual disabilities had significantly lower screening participation and completion rates compared to those without disabilities.
- Stool sample return increased with disability severity, but diagnostic examination rates after a positive test decreased with severity.
- Colonoscopies were more often incomplete for people with intellectual disabilities compared to those without.

## Abstract

Do people with intellectual disabilities participate in and complete colorectal cancer screening to the same extent as those without such disabilities?

In this register-based cohort study of 17 117 people with intellectual disabilities, screening participation and completion were significantly lower compared with a reference cohort. The proportion returning a stool sample increased with intellectual disability severity, whereas the proportion undergoing diagnostic examination after a positive screening test result decreased.

These findings indicate substantial inequities, highlighting the need for tailored strategies to ensure equitable colorectal cancer screening access for people with intellectual disability.

This cohort study examines participation in and completion of colorectal cancer screening among people with intellectual disabilities in Denmark.

Colorectal cancer mortality is elevated among people with intellectual disabilities, potentially because of delayed diagnosis.

To compare colorectal cancer screening participation and completion among people with and without intellectual disabilities.

This nationwide, register-based cohort study was conducted in Denmark, where all residents aged 50 to 74 years are invited to biennial, free-of-charge colorectal cancer screening. People with and without intellectual disabilities born between 1940 and 1973 and invited to colorectal cancer screening at least once between 2014 and 2023 were included.

Intellectual disability, defined as being registered with an intellectual disability diagnosis or a diagnosis most likely leading to intellectual disability. Disability severity (mild, moderate, severe, and profound) was available for a subpopulation.

The primary outcomes were colorectal cancer screening participation and completion, including stool sample return, screening results, and diagnostic examination (mainly colonoscopy) following a positive screening test result. The pseudo-observations method was used to estimate cumulative incidence differences and cumulative incidence ratios between people with and without intellectual disability.

The study included 17 117 people with (median [IQR] age, 55.2 [50.2 to 63.2] years; 8445 female [49.3%]) and 149 162 without (median [IQR] age, 54.8 [50.2 to 62.5] years; 75 324 female [50.5%]) intellectual disabilities. Among those, 5170 people with intellectual disabilities (30.2%) and 83 709 people without (56.1%) returned a stool sample within 90 days of first invitation (adjusted cumulative incidence difference, −23.2 percentage points; 95% CI, −24.0 to −22.4 percentage points), with participation increasing with disability severity (range, 1453 of 5293 individuals with mild [27.5%] to 198 of 488 individuals with profound [40.6%] intellectual disabilities). Nonanalyzable samples were more common among people with vs without intellectual disabilities (105 individuals [1.8%] vs 330 individuals [0.4%]). Among those with a positive screening test result, 347 people (70.5%) with intellectual disabilities and 4724 (90.2%) without underwent diagnostic examination (mainly colonoscopy) within 60 days (adjusted cumulative incidence difference, −17.9 percentage points; 95% CI, −22.1 to −13.7 percentage points). The proportion who underwent diagnostic examination decreased with increasing disability severity (range, 127 of 165 individuals with mild [77.0%] to 50 of 100 individuals with moderate to profound [50.0%] intellectual disabilities). Colonoscopies were more often incomplete among people with vs those without intellectual disabilities (109 individuals [28.2%] vs 673 individuals [13.8%]).

In this cohort study of people with and without intellectual disabilities, those with intellectual disabilities were less likely to participate in colorectal cancer screening and, when they did participate, more often encountered challenges with stool sample collection and colonoscopy completion. These disparities call for tailored, decision-supportive strategies to ensure equitable access to colorectal cancer screening.