The use of medication against attention deficit hyperactivity disorder in Denmark: a drug use study from a national perspective

Purpose The purpose of the study was to characterize the utilization of medication against attention deficit hyperactivity disorder (ADHD) in Denmark between 1995 and 2011 from a national perspective, by using population-based prescription data. Methods National data on drug use in Denmark between 1 January 1995 and 30 September 2011 were extracted from the Registry of Medicinal Product Statistics (RMPS). Drug utilization was characterized using descriptive statistics. Results A total of 1,085,090 prescriptions issued to 54,020 persons were identified. The incidence rate was stable in the last 3 years of the study period, and a slightly decreasing incidence rate and a stabilizing prevalence were observed towards the end of this period. The therapeutic intensity was 6.7 defined daily dose/person/day, with large regional differences that ranged from 64 to 145 % of the national average. Methylphenidate accounted for 92.6 % of DDDs used. The general practitioner (GP) rarely initiated treatment, although treatment initiation based on the GP’s advice increased with older age of the patient. Maintenance treatment was found to be distributed roughly equally between prescriber types. For methylphenidate, 1 % of users accounted for 6.1 % of the drug volume and 50 % of users accounted for 84.4 %. The data therefore do not suggest a high proportion of heavy users. Conclusion The findings of this analysis are mostly reassuring, with the data indicating a seemingly stagnant incidence and prevalence rate and lacking evidence of heavy users. However, the prescriber profile for incident users and the large regional variances raise concerns. It is therefore vital that the use of ADHD drugs is closely monitored.