Aims: Comorbidities are associated with inferior health outcomes but data on the influence of specific comorbidities is limited. We compared health outcomes between persons with and without cancer according to their index comorbidity using data from the Australian National Health Survey 2017-18.
Methods: A cross-sectional comparison of adults aged ≥25 years was performed comparing self-assessed health status (measure of perception of health, categorised as poor or good health) and mental distress (measure of negative emotional states, categorised as high-very high or low-moderate distress) between persons with and without cancer by 12 different comorbidities. Data were analysed using logistic regression with adjustment for sociodemographic and lifestyle factors.
Results: There were 1,982 persons (52% female) with and 12,635 persons (51% female) without cancer. Cancer patients were older (53% vs. 18% aged ≥65 years), more often born in Australia (80% vs. 67%) and have a comorbidity (91% vs. 75%) compared with those without cancer. Persons with cancer were more likely to report a poor health status than those without cancer for each comorbidity except for skin and infectious diseases; the adjusted odds ratio (aOR) ranged from 1.34 (95%CI=1.01-1.79) for digestive disorders to 2.11 (95%CI=1.78-2.52) for musculoskeletal diseases. A comorbid mental illness increased the odds of reporting both poor health status (aOR2.79, 95%CI=2.27-3.43) and mental distress (aOR9.01, 95%CI=7.25-11.20) the most. Comorbid blood conditions increased the odds of poor health (aOR2.93, 95%CI=1.62-5.29) but not distress (aOR1.27, 95%CI=0.68-2.35) alone.
Conclusions: Comorbidities in people with cancer were more common and were generally associated with inferior health status when compared to people without cancer, although the magnitude of the effect varied by comorbidity type. A comorbid mental illness was associated with the worst health outcomes for cancer survivors. Further research into identifying individuals at the highest risk of a poor health outcome is required for targeting interventions.