Impact of Polypharmacy on Health-Related Quality of Life in Dialysis Patients

Introduction: Dialysis patients are often prescribed a large number of medications to improve metabolic control and manage coexisting comorbidities. However, some studies suggest that a large number of medications could also detrimentally affect patients' health-related quality of life (HRQoL). Therefore, this study aims to provide insight in the association between the number of types of medications and HRQoL in dialysis patients. Methods: A multicentre cohort study was conducted among dialysis patients from Dutch dialysis centres 3 months after initiation of dialysis as part of the ongoing prospective DOMESTICO study. The number of types of medications, defined as the number of concomitantly prescribed types of drugs, was obtained from electronic patient records. Primary outcome was HRQoL measured with the Physical Component Summary (PCS) score and Mental Component Summary (MCS) score (range 0-100) of the Short Form 12. Secondary outcomes were number of symptoms (range 0-30) measured with the Dialysis Symptoms Index and self-rated health (range 0-100) measured with the EuroQol-5D-5L. Data were analysed using linear regression and adjusted for possible confounders, including comorbidity. Analyses for MCS and number of symptoms were performed after categorizing patients in tertiles according to their number of medications because assumptions of linearity were violated for these outcomes. Results: A total of 162 patients were included. Mean age of patients was 58 +/- 17 years, 35% were female, and 80% underwent haemodialysis. The mean number of medications was 12.2 +/- 4.5. Mean PCS and MCS were 36.6 +/- 10.2 and 46.8 +/- 10.0, respectively. The mean number of symptoms was 12.3 +/- 6.9 and the mean self-rated health 60.1 +/- 20.6. In adjusted analyses, PCS was 0.6 point lower for each additional medication (95% confidence interval [95% CI]: -0.9 to -0.2; p = 0.002). MCS was 4.9 point lower (95% CI: -8.8 to -1.0; p = 0.01) and 1.0 point lower (95% CI: -5.1-3.1; p = 0.63) for the highest and middle tertiles of medications, respectively, than for the lowest tertile. Patients in the highest tertile of medications reported 4.1 more symptoms than in the lowest tertile (95% CI: 1.5-6.6; p = 0.002), but no significant difference in the number of symptoms was observed between the middle and lowest tertiles. Self-rated health was 1.5 point lower for each medication (95% CI: -2.2 to -0.7; p < 0.001). Discussion/Conclusion: After adjustment for comorbidity and other confounders, a higher number of medications were associated with a lower PCS, MCS, and self-rated health in dialysis patients and with more symptoms.