Register-based indicators for potentially inappropriate medication in high-cost patients with excessive polypharmacy

Background: Excessive polypharmacy is often associated with inappropriate drug use. Because drug expenditures are heavily skewed and a considerable share of patients in the top 5% of the cost distribution have excessive polypharmacy, the appropriateness of their drug use should be reviewed.

Objectives: The aim of this study was to review the quality of drug use in patients with extremely high costs and excessive polypharmacy and to compare them with all drug users.

Research design: This is a nationwide register study.

Subjects: The subjects of this study were all drug users in Finland over 15 years of age, n = 3,303,813.

Measures: The measures used were annual total costs, average costs, and number of patients. The background characteristics used included gender, age, morbidity, number of prescribers, active substances, and indicators of potentially inappropriate drug use, for example, Beers criteria.

Results: The patients with high costs and excessive polypharmacy accounted for 22% of the total pharmaceutical expenditures but only 3% of drug users. One-third of them were elderly, compared with 11.3% of all drug users (p < 0.001). Almost all of them, 93.6%, had chronic disease compared with 34.0% of all the drug users (p < 0.001). The high-cost polypharmacy patients used more potentially inappropriate (28.0% vs 19.9%, p < 0.001) and anticholinergic drugs (26.7% vs. 9.6%, p < 0.001) and psychotropics more often simultaneously (20.4% vs. 3.8%, p < 0.001) than all drug users.

Conclusions: Excessive polypharmacy with inappropriate medication use should be prevented using all the methods. The patients with excessive polypharmacy and high-drug costs provide a most interesting group for containing pharmaceutical costs via medication reviews.