Impact of polypharmacy on all-cause mortality and hospitalization in incident hemodialysis patients: a cohort study

Background Polypharmacy (PP) is common in end-stage chronic renal disease patients largely due to the presence of multiple comorbid conditions. Although PP is potentially harmful, its relationship with mortality and morbidity in hemodialysis patients currently remains unclear. Methods Study design: cohort study. Setting: participants: one hundred and fifty-two initial hemodialysis patients (male, 88 patients; mean age, 70.3 years) were enrolled between February 2015 and March 2018 at Nobeoka Prefectural Hospital and Chiyoda Hospital. Predictor: patients were divided into 2 groups according to PP (6 or more drug prescriptions or less) during admission and discharge for the initiation of hemodialysis. Outcomes: all-cause mortality and hospitalization during the mean 2.8-year follow-up. Measurements: hazard ratios (HRs) were estimated using Cox’s model for the relationships between PP and clinical outcomes and adjusted for potential confounders. The group with 5 or less drug prescriptions was set as a reference. Results The number of prescribed drugs per patient averaged 7.4 at admission and 7.0 at discharge for initial hemodialysis. One hundred (65.8%) and 94 patients (61.8%) had PP at admission and discharge, respectively. During the follow-up, 20 patients died and 71 were hospitalized. PP at admission did not correlate with outcomes, whereas that at discharge correlated with all-cause hospitalization. Conclusions PP at discharge may be associated with clinical outcomes. However, it remains unclear whether PP is the direct cause of outcomes or is simply a marker for an increased risk of outcomes.