Utilization of oral antihyperglycemic drugs over a 7-year period (1998-2004) in a Hungarian population and adherence to drug therapy

Objective: To describe the quantitative and qualitative changes in the utilization of oral antihyperglycemic drugs (OAHDs) between 1998 and 2004 and to analyze patients' adherence to OAHD therapy. Methods: We conducted a retrospective analysis of the electronic database of the Hungarian National Health Fund Administration for the years 1998 through 2004. All 912,620 prescriptions for OAHDs dispensed for the 38,855 patients in Csongrad County ( 430,000 inhabitants) were retrieved and analyzed according to the ATC/DDD ( World Health Organization) methodology. Nonadherence was set as medication possession ratio < 80%. Results: The number of patients using OAHDs significantly increased ( P< 0.001); the yearly prevalence of 2.88% in 1998 increased to 4.32% in 2004. The overall consumption of OAHDs increased by 76%, from 20.85 defined daily doses per 1,000 inhabitants per day (DDD/TID) in 1998 to 36.83 DDD/TID in 2004. While in 1998 glibenclamide was the most often prescribed agent, received by 61.7% of patients, its share dropped to 16.1% in 2004, and metformin became the leading agent prescribed for 43.0% of patients. During the study period, the adherence rate varied between 47.9% and 49.2%. Women had a significantly better ( P< 0.001) adherence rate than men, 51.3% vs. 45.5%. The adherence rate peaked in patients between 60 and 79 years and was lowest in patients in their 30s. Conclusions: The utilization pattern of OAHDs considerably changed, but there were no significant changes in patients' adherence. The significant increase in the utilization of OAHDs is not the result of increased adherence but of increased patient number.