Artikel
Do defined daily doses (DDDs) reflect prescribing behaviour? A 3-month-analysis of data from a statutory health insurance company
Bilden Definierte Tagesdosen (DDDs) die Verordnungsrealität ab? Analyse von Krankenkassendaten
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Autoren
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Thomas Grimmsmann
- Medical Review Board of the Statutory Health Insurance Funds Mecklenburg-Vorpommern, Schwerin, Germany
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Wolfgang Himmel
- Dept. of General Practice / Family Medicine, University of Göttingen, Germany
| Veröffentlicht: | 6. November 2008 |
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Gliederung
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Background and aim: Although developed to study trends in drug consumption, the system of defined daily doses (DDDs), together with the ATC-system, is often used to compare costs between different treatments strategies or sometimes even to estimate the degree of the patients’ drug adherence. However, in order to use the DDD system as a powerful pharmacoepidemiological tool, it is essential that doctors prescribe 1 DDD per day for 1 patient, at least on average. The aim of this study was to explore to what degree doctors prescribe according to the ATC/DDD system.
Material and method: The database consisted of drug prescriptions for patients from a large statutory health insurance company. We analysed continuous prescriptions issued in primary care practices during the first 3 months of 2007 (n = 200,814 patients). The effectively prescribed daily doses for widely-used antihypertensive and anti-diabetic drugs were compared with the DDD.
Results: Selective beta blocking agents (ATC-Code C07AB) were prescribed with an average DDD of 0.9 (range for the different drugs within this group: 0.8 to 1.2). In contrast, the DDDs for all plain ACE-inhibitors (C09AA) were much higher (2.3), with a rather low DDD for Captopril (1.5) and the highest for Ramipril (3.5). Most patients (> 80%) received 2 or 4 DDDs of Ramipril; only 15% received 1 DDD. Similar effects could also be observed for anti-diabetic sulfonamides (A10BB) with a DDD of 1.0 for Glibenclamide and 2.0 for Glimepiride.
Conclusion: Depending on the drug group, the prescribed daily doses differed considerably from the DDD. This is even true for active substances of the same drug group. And even for a single drug, the DDDs differed considerably among individuals. As a result, comparisons of treatment costs as well as estimates of drug adherence on the basis of DDDs should be considered with caution.
