Trends in the consumption of attention deficit hyperactivity disorder medications in Castilla y León (Spain): changes in the consumption pattern following the introduction of extended release methylphenidate

Abstract

Background: Attention deficit hyperactivity disorder (ADHD) is the most diagnosed behavioural disorder in children and adolescents; prevalence has been estimated around 5%. Studies have shown an increase in the use of ADHD medications during the last years. The aim of the present study was to learn the pattern and the evolution of ADHD medication consumption in Castilla y León (Spain).

Method: Consumption data for the period 1992-2009 were obtained from databases containing information upon consumption and cost of medications dispensed by pharmacies at the expense of the Spanish National Health System. The data were expressed in defined daily doses (DDDs) per 1000 inhabitants per day (DDD/1000 inhabitants/day). A model to forecast consumption was built.

Results: Attention deficit hyperactivity disorder medication consumption increased in Castilla y León from 0.1 DDD/1000 inhabitants/day in 1992 to 1.5 DDD/1000 inhabitants/day in 2009; expected consumption will reach 2.5 DDD/1000 inhabitants/day by 2013. The drugs accounting for this increase were mainly made up of methylphenidate preparations (1.4 DDD/1000 inhabitants/day in 2009). From 1992 to 1999, there was a slight reduction in methylphenidate use; following amphetamine withdrawal, the consumption of stimulants began to increase, and figures showed a sharp rise after marketing of extended-release formulations in 2003.

Conclusions: There has been an enormous increase in ADHD medication consumption in Castilla y León in the last few years; increase rocketed when extended-release methylphenidate was marketed. A rapid increase in the consumption is a warning on possible overdiagnosis and inappropriate prescription.