Combined Medication with Stimulants and Non-stimulants for Attention-deficit/hyperactivity Disorder.

Objective To study the efficiency and indication of combined medication with a stimulant and non-stimulant for attention-deficiency/hyperactivity disorder (ADHD), herein, the authors examined children and adult patients with ADHD. Methods Subjects included patients diagnosed with ADHD who paid two or more visits to the outpatient clinic of the Kyung Hee University hospital from January 2009 to December 2019. The authors examined the age, sex, drugs, treatment adherence, and reason for combined medication. The subjects were classified into four groups: treatment with a non-stimulant (atomoxetine) only (Group ATX), treatment with a stimulant (methylphenidate immediate-release, extended-release, or osmotic-release oral system) only (Group MPH), exposed to both but separately used (Group SEP), and exposed to both with combined use (Group COM). The patient was considered adherent to treatment (1) on visiting the hospital ten or more times or consecutively for six months, and (2) medication possession ratio ≥ 0.8. Results Of 929 patients, 229 (24.7%) were female. Group ATX comprised 146 (15.7%) patients, Group MPH comprised 627 (67.5%) patients, Group SEP comprised 106 (11.4%) patients, and Group COM comprised 50 (5.4%) patients. Longer-term adherence was seen with combined medication and in females than with monopharmacy and in males. The main indication for combination was dose-limiting untoward effects. Conclusion These results suggest that combined medication would facilitate treatment adherence for ADHD. Further research is essential for the replication of these results in a large sample and the investigation of the indications for administering combined medication in children and adults with ADHD.