Hospitalization due to adverse drug events in older adults with cancer: A retrospective analysis

Geriatric oncology is a rapidly evolving field of practice, where comprehensive geriatric assessments (CGA) and multidisciplinary team (MDT) input have the potential to improve patient outcomes. Polypharmacy and potential drug interactions (PDI) have been associated with an increased risk of adverse outcomes in older adults with cancer, receiving systemic anti-cancer therapy (SACT). Our aim was to assess the incidence of unplanned hospitalization in older adults with cancer attending medical oncology outpatient clinics and to determine whether an unplanned hospitalization was potentially due to an adverse drug event (ADE).

We identified patients who attended a medical oncology outpatient appointment from January 1 to March 31, 2018. Medical records were examined to identify any unplanned hospital admissions between the clinic visit date and three and six months after initial clinic visit. Incidences of unplanned hospitalization were assessed to determine if an ADE potentially occurred.

Data collected from 174 patients were analyzed. Over half (57%) were female, median age was 75 years and 53% had a favorable performance status. The most common malignancies were gastrointestinal (GI) at 31% (n = 54), breast 29% (n = 51), and genitourinary 22% (n = 37). Seventy-two percent had advanced disease (stage III/IV) and 61% had systemic therapy (SACT and hormonal therapy). Polypharmacy (≥5 medications) was observed in 77% of patients. The total number of admissions at six months was 99, with 55% of these potentially due to an ADE. On multivariate analysis breast cancer (p ≤0.001), lung cancer (p = 0.034), performance status (p ≤0.001), monochemotherapy (p = 0.012), polychemotherapy (p ≤0.001), and radiotherapy (p = 0.048) were independent predictors of unplanned hospitalization. Breast cancer (p = 0.008), GI cancer (p = 0.019), monochemotherapy (p = 0.039), and polychemotherapy (p ≤0.001) were independent predictors of unplanned hospitalization due to ADE on multivariate analysis.

We observed that older adults with cancer have a high risk of unplanned hospitalization due to ADE. Medication review as part of a CGA in newly diagnosed older adults with cancer by a clinical pharmacist is recommended. This may identify opportunities to avoid medications that could potentially lead to unplanned hospitalization.