Health Service Use, Costs, and Adverse Events Associated with Potentially Inappropriate Medication in Old Age in Germany: Retrospective Matched Cohort Study

BACKGROUND: Drug-related problems are an important healthcare safety concern in the growing population of older people. Prescription of potentially inappropriate medication (PIM) is one aspect of this concern that is considered to increase the risk of adverse health outcomes.

OBJECTIVE: The aim of the Health Economics of Potentially Inappropriate Medication (HEPIME) study was to analyze the association between the prescription of PIMs according to the German PRISCUS list and healthcare utilization, healthcare costs, and the occurrence of adverse events in old age.

METHODS: Insurants of a large German health insurance company aged 65+ years were included in a retrospective matched cohort study. A total of 3,953,423 individuals with no exposure to PIM in 2011 were matched to 521,644 exposed individuals and compared in terms of outpatient healthcare utilization, healthcare costs, and the occurrence of adverse events in outpatient, hospital, and rehabilitation sectors during a 12-month follow-up.

RESULTS: On average, individuals in the exposed group had additional 143 [95% confidence interval (CI) 140-146] daily defined doses of pharmaceuticals and 4.5 (95% CI 4.4-4.6) days in hospital. Mean annual total healthcare costs per individual in the exposed group exceeded those in the non-exposed group by €2321 (95% CI 2269-2372), resulting mainly from differences in hospitalization costs of €1718 (95% CI 1678-1759). Odds ratios for the occurrence of adverse events in the exposed group were 1.32 (95% CI 1.32-1.34) in the outpatient sector, 1.76 (95% CI 1.73-1.79) in the hospital sector, and 1.82 (95% CI 1.76-1.89) in the rehabilitation sector.

CONCLUSIONS: Increased healthcare utilization and costs as well as an increased probability for adverse events in individuals exposed to PIM demonstrate the health economic relevance of PIM prescriptions. Whether avoiding PIM listed on the PRISCUS list may potentially improve the quality and efficiency of healthcare is currently unknown.