Risk Factors for Polypharmacy in Elderly Patients With Cancer Pain

Objective: Polypharmacy (PP) is a burden in elderly patients with cancer pain; however, risk factors for PP remain unclear. The purpose of this study was to investigate the risk factors for PP in this patient population. Methods: We retrospectively reviewed the medical charts of patients aged >= 65 years with cancer pain who were treated at Osaka University Hospital between February 2014 and June 2016 according to the World Health Organization 3-step ladder for cancer pain relief. We defined PP as >= 5 medications and conducted exploratory research to examine the association between PP and patient characteristics. Performance status (PS) was estimated according to the Eastern Cooperative Oncology Group system and is categorized as good PS (0-1) and poor PS (2-4). Results: We reviewed 206 patients (122 men and 84 women) with a median age of 71 years (range, 65-89 years) and found that 174 patients (84.5%) had PP. In multivariate logistic analysis, PP was significantly associated with an increased number of comorbidities (odds ratio [OR]: 4.93, 95% confidence interval [CI], 2.57-11.42, P < .001), poor PS (OR: 4.50, 95% CI, 1.06-31.68, P = .039), and administration of an anticancer or molecular targeted drug (OR: 2.78, 95% CI, 1.13-7.16, P = .025). Conclusions: An increased number of comorbidities, poor PS, and administration of an anticancer or molecular targeted drug were considered risk factors for PP in elderly patients with cancer pain. Sharing these risk factors with medical staff will help reduce the occurrence of problems associated with PP.