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

Purpose — 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.

Methods — 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.

Results — 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.

Conclusion — 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.