Intellectual and developmental disabilities (IDD) and cancer symptom reporting: a matched retrospective cohort study

Symptom assessment is key to managing symptom burden following a cancer diagnosis. Adults with intellectual or developmental disabilities (IDD) experience worse outcomes from cancer; disparities may also exist in routine cancer symptom screening. This study investigated whether differences exist in routine cancer symptom assessment between people with and without IDD in a public healthcare system.

We conducted a matched retrospective cohort study of adults in Ontario, Canada, with and without IDD who received a cancer diagnosis between 2010 and 2019 using administrative health data. Among people with cancer, those with IDD were hard-matched 1:5 to those without IDD on age at diagnosis, sex, diagnosis year, cancer type and regional cancer centre registration. Cumulative incidence of first symptom assessment accounting for death as a competing risk was estimated. Sub-distribution and cause-specific hazards models were used. Effect modification by age, sex and cancer stage was investigated.

A total of 1545 people with IDD were matched to 7725 people without IDD. Individuals with IDD experienced a lower incidence of cancer symptom assessment (1-year probability: 0.62 vs. 0.77) and lower rates of symptom assessment (sub-distribution HR: 0.63, 95% CI: 0.59, 0.67; cause-specific HR: 0.69, 95% CI: 0.65, 0.73) relative to those without IDD. Results were most pronounced for those in advanced cancer stages.

Among persons with cancer, the incidence of symptom assessment is lower for individuals with IDD compared to those without; the magnitude of these findings varied across cancer stages. These findings may indicate systemic barriers to equitable healthcare access for people with cancer and IDD.