Attention Deficit/Hyperactivity Disorder among Adults in the United States

Abstract

The purpose of the study was to use a single national data source to discern trends in the prevalence of office-based physician-patient encounters (office-based visits; OBVs) resulting in a diagnosis of attention deficit/hyperactivity disorder (ADHD), and use of pharmacotherapy for ADHD, among adults in the US. Data from the US National Ambulatory Medical Care Survey (NAMCS) for the years 1995–2008, were examined. The US NAMCS is a national probability sample designed and conducted by the US National Center for Health Statistics of the US Centers for Disease Control and Prevention. ADHD was defined as International Classification of Diseases, 9 th Revision, Clinical Modification codes 314.00 or 314.01. Data were partitioned into seven, 2-year time intervals for trend analysis. Annualized mean population-adjusted rates per 2-year intervals (per 1000) were based on US Census Bureau national resident population estimates for persons aged ≥20 years. Comparisons across time-frames were assessed by chi-square (χ2) analysis. The a priori level of significance for all statistical tests was set at p < 0.05. Analyses were performed using SAS® (Release 9.1.3, SAS® Institute Inc., Cary, NC, USA). The rate of OBVs documenting a diagnosis of ADHD increased from 3.1 per 1000 persons aged ≥20 years in 1995–6 to 14.5 in 2007–8; a 4.7-fold increase (p < 0.05). The rate of OBVs documenting a diagnosis of ADHD, and use of pharmacotherapy for ADHD, increased from 1.9 per 1000 persons aged ≥20 years in 1995–6 to 11.4 in 2007–8; a 6-fold increase (p < 0.05). ADHD is one of the most common psychiatric behavioural disorders in children, and its symptoms have been shown to persist well into adulthood. Over the 14-year time-frame examined, the rate of diagnosis of ADHD, and use of pharmacotherapy for ADHD, increased among adults (p < 0.05).