National trends in the prevalence of attention-deficit/hyperactivity disorder and the prescribing of methylphenidate among school-age children: 1990-1995

It has been reported that during the past decade the prevalence of attention-deficit/ hyperactivity disorder (ADHD) (ICD-9-CM code 314.00 or 314.01) and its pharmacologic treatment have increased dramatically in the United States. Herein, a single national data source is used to discern trends in the prevalence of U.S. office-based visits resulting in a diagnosis of ADHD, and trends in the prescribing of stimulant pharmacotherapy (including methylphenidate) for its treatment. Data from the National Ambulatory Medical Care Survey (NAMCS) for the years 1990 through 1995, for children aged 5 through 18 years, were utilized for this analysis. Results indicate that the number of office-based visits documenting a. diagnosis of ADHD increased from 947,208 in 1990, to 2,357,833 in 1995, Between 1990 and 1995, the number of visits by girls diagnosed with ADHD rose 3.9-fold (p<0.05), and the mean patient age increased by more than 1 year, from 9.7 in 1990, to 10.8 in 1995 (p<0.05). The percentage of office-based visits resulting in a diagnosis of ADHD increased from 1.1% of all visits ill this age group in 1990, to 2.8% by 1995. We discerned a 2,3-fold increase (p<0.05) in the population-adjusted rate of office-based visits documenting a diagnosis of ADHD; a 2.9-fold increase (p<0.05) in the population-adjusted rate of ADHD patients prescribed stimulant pharmacotherapy; and a 2.6-fold increase (p<0.05) in the population-adjusted rate of ADHD patients prescribed methylphenidate.