Medication Regimen Complexity and Adherence in Haemodialysis Patients: An Exploratory Study

Background: The impact of medication regimen complexity on adherence in hemodialysis patients is unknown. We investigated regimen complexity, perceived burden of medicines (PBM) and health-related quality of life (HR-QoL) as potential predictors of adherence.

Methods: Adult (≥18 years) hemodialysis patients were included. Data on medication regimen complexity index (MRCI), self-reported and objective adherence, comorbidity index, PBM and HR-QoL were obtained using established measures. Sociodemographic and clinical characteristics were collected during interviews and by reviewing medical records. Predictors of adherence were determined using logistic regression.

Results: Fifty-three out of 70 hemodialysis patients participated (response rate 75%; male 58.5%; age 67.9 ± 11.5 years). The mean MRCI, HR-QoL and PBM scores were 27.0 ± 10.9, 0.70 ± 0.13 and 1.7 ± 0.6, respectively. Based on self-reports, 43.4% (n = 23) were adherent, whereas for a subset of patients analyzed using objective measure (n = 33), much lower adherence rate was observed (27.3%, n = 9). The self-reported and objective measures were significantly correlated (r = 0.43, p = 0.01). Older age was the only significant predictor of self-reported adherence (OR 1.05; 95% CI 1.00-1.11) whereas older age (OR 1.10; 95% CI 1.00-1.21), higher comorbidity (OR 1.58; 95% CI 1.03-2.42) and MRCI (OR 1.14; 95% CI 1.02-1.27) were independent predictors of objective adherence.

Conclusions: The findings of this exploratory study suggest that older patients with high comorbidities and highly complex regimen are more likely to be adherent based on an objective measure. Future research is needed using objective measures of adherence suitable for all patients and reflecting all medications.