Objective: Attention-deficit/hyperactivity disorder (ADHD) in adults may result in functional impairment warranting clinical interventions. However, few studies have investigated the diagnosis and treatment rates of adult ADHD in non-Caucasian ethnic groups. This study used nationwide population-based data to investigate the rate of diagnosis, associated characteristics, and pharmacological treatment for adult ADHD in Taiwan.
Methods: Adults (age ≥18 years) newly diagnosed with ADHD (n=5,397) between January 2000 and December 2011 were enrolled from the National Health Insurance database in Taiwan. All patients were monitored until December 31, 2011. Patients who received treatment with immediate-release methylphenidate (IR-MPH), osmotic release oral system-methylphenidate (OROS-MPH), and atomoxetine (ATX) were analyzed.
Results: The cumulative prevalence of adult ADHD was 0.028%, and the incidence increased 10.9-fold from 2000 to 2011. The male to female ratio was 1.16, and 74.9% of the patients had the inattentive type. Overall, 55% of the patients received drug therapy for ADHD, and the average treatment duration was 478.3 days. Of the total patients, 50.4%, 13.3%, and 1.7% were prescribed with IR-MPH, OROS-MPH, and ATX, for a mean duration of 453.9, 327.7, and 161.4 days, respectively.
Conclusion: This population-based study showed an increasing trend in the diagnosis rate of adult ADHD; however, this rate is still low compared with Western countries. Approximately 45% of the adult patients with ADHD never received medication for their ADHD. Continuous efforts are needed to increase public awareness of adult ADHD.
Keywords: ADHD; comorbidity; drug adherence; epidemiology; gender difference; non-Caucasian.