Effects of clinical and socioeconomic factors on Medicare and patient costs for colorectal cancer in Australia: a retrospective multivariate regression analysis

Objective: We study how clinical and socioeconomic factors influence colorectal cancer (CRC) costs for patients and Medicare in Australia. The study seeks to extend the limited Australian literature on CRC costs by analysing comprehensive patient-level medical services and pharmaceutical cost data.

Design, setting and participants: Using the Victorian Cancer Registry, we identified all patients in Victoria who were diagnosed with CRC from 2010 to 2019 and extracted their linked 2010-2021 Medicare data. This data includes expenses from the Pharmaceutical Benefits Scheme and Medicare Benefits Schedule services. We examined variables such as disease stage, CRC type, molecular profile, metastasis status and demographics (eg, age, birth country, socioeconomic level via the SEIFA index, and native language). We applied descriptive and log-linear multivariate regression analyses to explore patient and Medicare costs related to CRC treatment.

Results: Costs significantly rise with advanced cancer stages, especially on medication costs. Patients' average out-of-pocket (OOP) expenses are roughly $A441 per year. Key cost influencers are gender, age and socioeconomic status. On average, males incur 13.5% higher annual costs, a significantly larger OOP expense, than females. Compared with patients aged 50 or below, there is a 7.1% cost increase for individuals aged 50-70 and an 8.8% decrease post-70, likely reflecting less intensive treatment for the elderly. Socioeconomic factors show a clear gradient. Wealthier areas experience higher costs, especially among native English speakers. Costs also vary based on cancer's anatomical location and specific genetic mutations.

Conclusion: The research highlights that CRC treatment expenses for patients and Medicare differ considerably due to factors such as diagnostic stage, demographics, anatomical location of the tumour and mutations. These cost variations lead to concerns about healthcare equality and decision-making autonomy. Policymakers may need to focus on early detection, increased support for advanced-stage patients, gender-sensitive healthcare, and equitable access to treatment across different socioeconomic groups.