Association of polypharmacy with all‐cause mortality and adverse events among elderly colorectal cancer survivors

Background The risk of inappropriate drug exposure in elderly colorectal cancer (CRC) survivors after the initial cancer treatment has not been well studied. This study investigated the association of polypharmacy (PP) with overall survival, hospitalization, and emergency room (ER) visits among older CRC survivors. Methods A retrospective cohort study was conducted using the Korean National Health Insurance claims data follow‐up from 2002 to 2017. Participants comprised those aged ≥65 years who were hospitalized with a diagnosis of CRC received cancer treatment and survived at least 2 years from the initial CRC diagnosis between 2003 and 2012. PP was defined based on the number of individual drugs during the third year, after 2 years of survival since the initial cancer treatment. PP was categorized as follows: non‐PP (zero to four prescribed drugs); PP (five to nine drugs), and excessive PP (≥10 drugs). Main outcomes are all‐cause mortality, hospitalization, and ER visits. Results Of the 55,228 participants, 44.5% died, 83.1% were hospitalized, and 46.1% visited the ER. The PP and excess PP groups showed increased risk of all‐cause mortality, hospitalization, and ER visit compared with the low PP group, and was highly associated among groups including patients aged 65 to 74 years and those in low‐level frailty groups. Conclusions These risks can be minimized by increasing awareness and enhancing behaviors among health care professionals, especially clinician and pharmacists, to be aware of potential drug interactions, review, and ongoing monitoring. Plain Language Summary The risk of inappropriate drug exposure in older colorectal cancer (CRC) survivors after the initial cancer treatment has not been well studied. Polypharmacy was associated with adverse outcomes, including all‐cause mortality, hospitalization, and emergency room visits among older CRC survivors and it was particularly associated with those who were 65 to 75 years and those with low risk of frailty. When prescribing drugs, physicians should be mindful of finding a balance between adequate treatment of diseases and avoiding adverse drug effects in survivors of CRC. The risk of inappropriate drug exposure in elderly colorectal cancer (CRC) survivors after the initial cancer treatment has not been well studied. Polypharmacy was associated with adverse outcomes, including all‐cause mortality, hospitalization, and emergency room visits among elderly CRC survivors, and it was particularly assoc