Duplicative medications in patients who visit multiple medical institutions among the insured of a corporate health insurance society in Japan

ObjectiveThe objective of this paper is to describe the frequency of duplicative medication use and to estimate the drug cost associated with duplicative medications in patients who visit multiple medical institutions in Japan.MethodsThe subjects of this study were insurants of a corporate health insurance society. We examined claims of insurants who received prescriptions from multiple medical institutions in April 2002. We examined characteristics of insurants who received duplicative medications and calculated the cost of duplicated drugs.Results8.8% received drugs with the same mechanism of action for overlapping administration periods. In terms of comparison among three age groups, 0–19 years old, 20–69 years old, and 70 years old or older, the percentage was higher in 0–19-year-old patients than in the other age groups. The cost of duplicated drugs was found to be 0.7% or 0.5% of the total drug cost, when calculated with higher-priced drugs and lower-priced drugs, respectively.ConclusionsThis study suggests that pediatric and teenage patients as well as elderly patients require prudent management of medication to avoid duplicative medications and that at least an estimated 5.2–7.2 billion yen may be saved if duplicative medications can be completely eliminated nationwide.