(P-402) Polypharmacy and Health-related Quality of Life in Older Adults with Cancer: Determining Breakpoints

Background: Polypharmacy is commonly defined as use of five or more medications. However, the optimal cut-off point associated with patient reported outcomes may be different.

Objectives: To determine the polypharmacy (PP) breakpoints that affect the health-related quality of life (HRQoL) outcomes among older adults with cancer.

Methods: This is a cross-sectional retrospective study using data from 2012-2016 longitudinal panels of the Medical Expenditure Panel Survey (MEPS). Adults aged > 65 years and with a diagnosis of cancer during the baseline year were included in the study. The exposure evaluated was polypharmacy, assessed as the number of therapeutic drug classes taken concurrently. The main outcome evaluated was HRQoL, measured using the physical component summary (PCS) and mental component summary (MCS) scores calculated based on the 12-item short form (SF-12) health survey. Multivariable linear regression and segmented regression were used to identify the PP breakpoints that were associated with PCS and MCS. Covariates used for risk adjustment were age, sex, race, marital status, education, income, insurance, region, Charlson comorbidity index and cancer type.

Results: In this study, 1,508 adults 65 years and above with cancer were included. The median number of drugs used was 6 (range: 1 to 24). The mean PCS and MCS scores for the eligible respondents were 40.71 (SE, 0.427) and 52.52 (SE, 0.30), respectively. A single breakpoint in PP at 14 (coefficient=-0.85, 95%CI -1.04 to -0.66) for PCS and 11 for MCS (coefficient=-0.36, 95%CI -0.56 to -0.16) was observed. A subsequent analysis examined the possibility of more than a single breakpoint. Two breakpoints in PP at 6 (coefficient=-0.57, 95%CI -1.03 to -0.10) and 11 (coefficient=-1.25, 95%CI -2.02 to -0.49) were found for PCS.

Conclusions: Our results suggest that different and multiple cut-off points are associated with an adverse impact on physical and mental health among older adults with cancer. A significant decline in PCS was observed for the number of medications up to 14 and a significant decline in MCS was observed for the number of medications up to 11. Another model with two breakpoints demonstrated a 1.25-point decline in PCS for each additional drug class between 6 and 11. Interventions to reduce the number of medications taken such as deprescribing, may need to be developed to improve HRQoL among older adults with cancer. These results may help in quickly identifying patients eligible for potential interventions.