Prevalence and risk of polypharmacy among the elderly in an outpatient setting: a retrospective cohort study in the Emilia-Romagna region, Italy.

Background: Polypharmacy, the simultaneous taking of many medications, has been well documented and is a topic of much concern for those looking to improve the quality of care for the elderly. Elderly patients often develop complicated and multifactorial health states that require extensive pharmacotherapy, leaving this population at risk for exposure to drug-drug interactions and other adverse events. Previous literature supports an association between an increase in the rate of adverse events as the number of drugs taken by a patient increases.

Objective: We sought to evaluate the prevalence of polypharmacy, and to determine patient characteristics that are predictive of exposure to polypharmacy, in the elderly population of the Emilia-Romagna region in Italy.

Methods: We conducted a retrospective cohort study of the 2007 Emilia-Romagna outpatient pharmacy database linked with patient information available from a demographic file of approximately 1 million Emilia-Romagna residents aged ≥65 years. The cohort comprised 887,165 elderly subjects who had at least one prescription filled during the study year. Using the WHO's defined daily dose (DDD) to determine the duration of treatment for a given drug, we defined a polypharmacy episode as overlapping treatment with five or more medications occurring for at least 1 day. The prevalence of polypharmacy was measured together with subject characteristics found to be predictive of polypharmacy exposure.

Results: A total of 349,689 elderly people in the population (39.4%) were exposed to at least one episode of polypharmacy during the study period. The prevalence of polypharmacy substantially increased with age and with a higher number of chronic conditions. Over 35% of those exposed to polypharmacy were exposed for 101 or more days of the year. The top three classes of medications involved in polypharmacy were antithrombotics, peptic ulcer disease and gastro-oesophageal reflux disease agents, and ACE inhibitors. The odds of exposure to polypharmacy were higher for older subjects, males and subjects living in urban areas.

Conclusions: This study provides evidence that the prevalence of polypharmacy in the elderly in Emilia-Romagna is substantial. Educational programmes should be developed to inform clinicians about the magnitude of the polypharmacy phenomenon and the patient characteristics associated with polypharmacy. Raising physicians' awareness of polypharmacy may help to ensure safe, effective and appropriate use of medication in the elderly.