Mental Health Comorbidity Raises Acute Care Use in Cancer

Key Takeaways

• In this Australian linked-data cohort of 99,230 adults receiving non-admitted oncology care, 10.5% had a recorded mental health condition.
• After matching, recorded mental health conditions were associated with 36% higher unplanned emergency department use and 31% higher unplanned hospitalization over 12 months than in matched peers without a mental health diagnosis.
• Cancer-related hospitalizations were 46% higher over 12 months in the matched mental health comorbidity group, and the difference was statistically significant.
• Virtual care use, digestive and lung cancers relative to breast cancer, and physical comorbidities were also associated with greater unplanned service use.
• The authors describe this pattern as a substantial inequity in unplanned acute care for people with cancer and mental health conditions in Australian services.

Adults living with both cancer and mental health conditions can face added psychosocial needs and more complex contact with hospital-based services as they move through oncology care in Australia. Whether that comorbidity is linked to more unplanned acute care than would be seen in otherwise similar patients without a recorded mental health diagnosis has remained unclear in routine oncology pathways. That gap led to a linked-data evaluation across multiple Australian states.

The Australian matched study of unplanned service use in cancer and mental health comorbidity was a retrospective matched case-comparison using linked data from three Australian states. It included adults aged 18 years or older living with cancer who had a non-admitted patient oncology encounter between 2018 and 2021; 99,230 people were in the cohort, including 10,442 with recorded mental health conditions. Patients with and without a mental health diagnosis were matched 1:1 with propensity scores, and oncology, cancer registry, hospital admission, emergency department (ED), outpatient mental health, and mortality records were linked. Negative binomial regression adjusted for sociodemographic and clinical factors assessed unplanned ED presentations or hospitalizations within 12 months.

Over 12 months, higher unplanned ED use and hospitalization among matched patients with mental health conditions was observed after matching: risk was 36% higher for unplanned ED use, 31% higher for unplanned hospitalizations, and 46% higher for cancer-related hospitalizations than in matched patients without a mental health diagnosis. Virtual care use, digestive and lung cancers relative to breast cancer, and physical comorbidities were also associated with increased unplanned use.

Because this was a retrospective matched analysis of routine-care data, the findings support association rather than causation. The abstract does not quantify the links seen with virtual care, cancer type, or physical comorbidity, and the implications should be read in the context of Australian oncology and hospital services. Within that setting, the authors frame the pattern as substantial inequities in unplanned acute care for people with cancer and mental health conditions and suggest that closer oncology-mental health integration, along with refined virtual care delivery, may help reduce avoidable acute care use.

In this Australian analysis, adults with cancer and recorded mental health conditions experienced more unplanned acute care use than matched peers without a mental health diagnosis. The authors present the finding as a health-services inequity signal rather than an intervention result.

Clinician Questions

Which patients were included in the Australian analysis of cancer and mental health comorbidity?

The study included adults aged 18 years or older living with cancer who had a non-admitted oncology encounter between 2018 and 2021 in three Australian states, with comparisons made between matched patients with and without a recorded mental health diagnosis. The findings are therefore most applicable to ambulatory oncology populations in that Australian setting.

How was unplanned health service use measured in adults with cancer and mental health conditions?

Investigators examined unplanned emergency department presentations or hospitalizations within 12 months, and they also reported cancer-related hospitalizations as a separate outcome. This outcome definition focuses on acute care after outpatient oncology contact rather than on planned cancer treatment visits.

What other factors were associated with increased unplanned service use besides mental health comorbidity in this cancer cohort?

Virtual care use, digestive and lung cancers compared with breast cancer, and physical comorbidities were also associated with increased unplanned use in this cohort. The abstract does not report the magnitude of those associations.