Polypharmacy is a common occurrence, especially among the older patient population. An estimated 48% to 80% of older patients with cancer have multiple comorbidities that require pharmacologic management. Results from a study published in the Journal of Geriatric Oncology  indicate that the number of medications used by older oncology patients in the 6 months before initiating IV chemotherapy is predictive of their posttreatment risk for inpatient hospitalization.

This recent real-world, population-based study explored the relationship between polypharmacy and inpatient hospitalization among older adults with prostate, breast, and lung cancer treated with IV chemotherapy. This appears to be the first and largest population-based study to examine the relationship between polypharmacy and inpatient hospitalization among older adults with cancer receiving chemotherapy. This study also examined various polypharmacy cutoff points to identify expanded risk for inpatient utilization.

The researchers’ chief data source was the Surveillance, Epidemiology, and End Results-Medicare linked files. Patients (aged 65 years and older) were included if they were diagnosed with prostate (n = 1,430), breast (n = 5,490), or lung cancer (n = 7,309) from 1991 to 2013 and received IV chemotherapy between 2011 and 2014. The number of medications during the 6-month window, before IV chemotherapy initiation determined polypharmacy status. The researchers used negative binomial models to evaluate the association between polypharmacy and postchemotherapy inpatient hospitalizations, which were presented as incidence-rate ratios. The endpoint was the total number of inpatient hospital admissions divided by the total time at risk, defined as the total time alive in the 6-month period after chemotherapy initiation minus the time spent in the hospital.  

In the study, researchers identified 13,959 patients with prostate, breast, or lung cancer treated with IV chemotherapy. The median number of prescribed medications during the 6-month window before IV chemotherapy initiation was high: 10 among patients with prostate cancer, nine among patients with breast cancer, and 11 among patients with lung cancer. 

Compared with patients taking fewer than five prescriptions, the postchemotherapy hospitalization rate for patients with prostate cancer was 42%, 75%, and 114% higher among those taking five to nine, 10 to 14, and 15 or more medications, respectively. Patients with breast cancer and those with lung cancer demonstrated comparable patterns.

Compared with patients taking five or fewer concurrent medications, hospitalization rates were 36%, 49%, and 82% higher for patients with lung cancer taking five to nine, 10 to 14, and 15 or more concurrent medications, respectively. Among those with breast cancer, hospitalization rates were 17%, 61%, and 101% higher, respectively.

The researchers concluded that this large, population-based study demonstrated a high incidence of polypharmacy among older adults treated with chemotherapy. Moreover, the number of medications used before chemotherapy was extremely predictive of the risk of postchemotherapy inpatient hospitalization. 

Most chemotherapy regimens are based on data from clinical trials, which often exclude or underrepresent patients with multiple comorbidities. Therefore, little is known about the outcomes of older adults with cancer treated with chemotherapy while taking several medications. The researchers noted that their research findings emphasize a substantial area of concern and a research area that is poised for quality improvement. 

They also noted that a reasonable next step would be to conduct a prospective randomized, controlled trial to ascertain whether enhanced medication management can diminish inpatient hospitalization and other healthcare resource utilization among older adults treated with chemotherapy.
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