Polypharmacy and excessive polypharmacy in community-dwelling middle aged and aged adults between 2011 and 2015.

Aims: We aimed to assess the prevalence, components and evolution of polypharmacy and to evaluate risk factors associated with polypharmacy.

Methods: A retrospective dynamic cohort study was performed, using a primary healthcare database comprising Flemish community-dwelling adults aged ≥40 years between 2011 and 2015. Polypharmacy and excessive polypharmacy were defined as the use of 5-9 or minimum 10 different medications during 1 year, respectively. Temporal changes were analysed using an autoregressive error model. Risk factors for polypharmacy were evaluated using logistic regression.

Results: In total, 68 426 patients were included in the analysis. The prevalence of polypharmacy was 29.5% and 16.1% for excessive polypharmacy in 2015. The age-standardised prevalence rate of patients using minimum five medications increased with 1.3% per year (95% confidence interval (CI): 0.1968-2.4279). The mean number of unplanned hospital admissions was 0.07 (standard deviation (SD) 0.33) for polypharmacy patients and 0.19 (SD 0.53) for excessive polypharmacy patients. Four risk factors were found to be significantly correlated with polypharmacy: age (odds ratio (OR) 1.015; 95% CI: 1.013-1.017), female gender (OR 1.161; 95% CI: 1.108-1.216), number of chronic diseases (OR 1.126; 95% CI: 1.114-1.139) and number of general practitioner contacts (OR 1.283; 95% CI: 1.274-1.292).

Conclusion: The prevalence of polypharmacy increased between 2011 and 2015. Polypharmacy and excessive polypharmacy patients appeared to differ based on our observations of characteristics, drug therapy and outcomes. Age, female gender, number of chronic diseases and number of general practitioner contacts were associated with polypharmacy.