Patterns of combined prescriptions of aspirin-Ginkgo biloba in Taiwan:: a population-based study

Background and objectives: Although interactions between aspirin and Ginkgo biloba extract (GBE) have been documented, the extent to which these two drugs are used in combination remains unclear. The aim of this study was to estimate the extent and utilization patterns of combined prescriptions of aspirin and GBE in Taiwan based on an analysis of a nationwide database. Methods: A representative nationwide sample of 200 000 National Health Insurance (NHI) beneficiaries in Taiwan was used. The prescription details of ambulatory care claims for this sample of beneficiaries for the period 1997-2003 were analysed. The prevalence of aspirin and GBE prescriptions was evaluated. The extent of co-prescription of the two drugs was assessed together with the associated patient characteristics. Results: There was an increase in the number of aspirin prescriptions (from 29 986 out of 2 454 879 (1.2%) in 1997, to 50 614 out of 2 499 605 (2.0%) in 2003). Aspirin was mostly prescribed to patients over 50 years old. The percentage of prescriptions with aspirin increased rapidly from 57% to 84%, among those over 50 years old. The number of prescriptions with GBE also increased from 3039 to 6171 and 78-84% was prescribed to those 50 years or older. During the study period, combined prescriptions of aspirin and GBE dramatically increased four times. Most prescriptions were longer than 14 days and 42.4% of combined prescriptions were found to be at the same ambulatory care visit. Conclusion: The findings of this study suggest that there is an increasing trend in co-prescription of aspirin and GBE for Taiwan's elderly population during 1997-2003. This trend is of concern and worthy of note.