Medical and economic factors influencing generic drug use in the Japanese public health system: Influencing factors in different populations.

Factors influencing generic drug use must be considered when new drug policies are established and initiatives are implemented to promote generic drug use. This study was conducted to elucidate medical and economic factors that influence generic drug use in the Japanese public health system by evaluating the degree of generic drug use via a multivariate analysis. We conducted a retrospective study of medications administered to inpatients at Gifu Municipal Hospital (Japan) from November 1 to 14, 2014. Details of inpatients (age, sex, and type of medical insurance) and the drugs administered (prescribing institution, dispensing pharmacy, price, and class) were assessed. A total of 1409 drugs (original, 639; generic, 770) were analyzed. Multivariate analysis showed significant differences in out-of-pocket medical fees [odds ratio (OR), 0.595], drugs prescribed at Gifu Municipal Hospital (OR, 1.811), drugs prepared at a health insurance pharmacy (OR, 1.541), drugs containing the same active substances as in the generic drugs used at Gifu Municipal Hospital (OR, 3.712), and drugs costing ≥30 yen and containing the same active substance/having the same specifications (OR, 0.516). Drugs prescribed at a large key hospital in the community with high adoption rates of generic drugs, drugs containing the same active substances as the generic drugs adopted by the hospital, and drugs prepared at health insurance pharmacies contributed to a more frequent use of generic drugs. By contrast, out-of-pocket medical fees and being prescribed expensive drugs contributed to the less frequent use of generic drugs.