High polypharmacy rates among Australian colorectal cancer survivors are ‘concerning’, according to researchers.
New Australian research has identified how frequently patients with colorectal cancer are affected by polypharmacy – and which groups are more likely to end up on multiple medications at the same time.
Colorectal cancer is one of the most common cancers in Australia. The way CRC patients use medication changes over the course of their cancer journey, with patients often ending up on multiple medications at the same time. Research in other populations, such as those undergoing surgery or chemotherapy, has linked polypharmacy to increased risks of inappropriate medication use, adverse events and death. However, less is known about polypharmacy in post-treatment survivors of CRC.
To address this shortcoming, Australian researchers undertook a population-based, retrospective cohort study where they examined medicine use in the year prior to CRC diagnosis, through active treatment and up to five years post-diagnosis. They found that more than 70% of CRC patients experienced polypharmacy at some point during the study, with almost 50% experiencing polypharmacy in years two to five post-diagnosis.
“Our study found that medicine use changes following diagnosis and primary cancer treatment, with increased use of analgesic and psychotropic medication over time. Quality survivorship should address the unique challenges arising post-CRC diagnosis, such as ongoing neuropathy, pain or psychological symptoms and prioritise prevention and management of non-cancer comorbidity,” the researchers wrote in The Oncologist.
Researchers used the Medicines Intelligence Data Platform, a linked data collection built around the electronic health records for all adults living in New South Wales, to explore polypharmacy in CRC patients. The medical record data were linked with dispensing records held by the Pharmaceutical Benefits Scheme, hospital admissions data from the NSW Admitted Patient Data Collection, cancer-specific data from the NSW Cancer Registry and death data from the National Death Index.
This approach identified 19,056 adults diagnosed with CRC over a five-year period, with 6797 (35%) diagnosed with localised disease, 8482 (45%) diagnosed with regional disease and 3777 (20%) diagnosed with metastatic disease. The five-year survival rate was higher in patients with localised and regional disease (87% and 78%, respectively) compared to the metastatic disease group (27%).
The proportion of patients who experienced polypharmacy – defined as being exposed to five or more medications at the same time for at least one 90-day quarter of the year around the date of CRC diagnosis – at any time during the study was similar: 74% in the localised group, 79% in the regional group and 79% in the metastatic group.
The number of medications dispensed per patient increased in the first 12 months following CRC diagnosis, with 30%, 37% and 38% of people with localised, regional and metastatic disease dispensed at least 10 unique medications during this timeframe.
Females, people aged 75 years and older, patients with comorbidities and individuals from more socioeconomically disadvantaged areas were more likely to experience polypharmacy in the 12 months prior to CRC diagnosis compared to men, younger patients, people without comorbidities and those from more advantaged areas.
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Similarly, age, the presence of comorbidities and socioeconomic disadvantage were also associated with an increased likelihood of polypharmacy between the fourth and fifth year after diagnosis.
“To our knowledge, this is the first study to explore polypharmacy in Australians with CRC,” the researchers wrote. “Our findings highlight that medicine use is dynamic, with the number of medicines dispensed increasing for our cohort during the year following diagnosis, likely coinciding with primary cancer therapies, before returning to pre-diagnosis levels for most people.”
“The composition of the most dispensed medicines changed slightly during the year following diagnosis, reflecting increased dispensings of supportive medicines, such as antiemetics, painkillers and antidepressants.
“Notably, opioids, other analgesics and antidepressants remained amongst the most commonly dispensed medicines throughout the post-active treatment survivorship period.
“For patients treated with curative intent, higher-than-expected rates of polypharmacy are particularly concerning, as they indicate excess morbidity and impaired quality of life among survivors who have been cured of cancer but continue to experience poorer health than the general population.”
