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Background: Clinical studies found that medication for attention-deficit/hyperactivity disorder (ADHD) is effective in coexisting autism spectrum disorder (ASD), but current research is based on small clinical studies mainly performed on children or adolescents. We here use register data to examine if individuals with ADHD and coexisting ASD present differences in the prescribing patterns of ADHD medication when compared to individuals with pure ADHD., Methods: Data with information on filled prescriptions and diagnoses was retrieved from the Swedish Prescribed Drug Register and the National Patient Register. We identified 34,374 individuals with pure ADHD and 5012 individuals with ADHD and coexisting ASD, aged between 3 and 80 years. The first treatment episode with ADHD medications (≥ 2 filled prescriptions within 90 days) and daily doses of methylphenidate during a 3-year period was measured. Odds ratios (ORs) were calculated for the likelihood of being prescribed ADHD medication in individuals with and without ASD and Wilcoxon rank-sum test was used to compare group differences in dose per day., Results: Individuals with ADHD and coexisting ASD were less likely to start continuous treatment with ADHD medication (ADHD 80.5%; ADHD with ASD 76.2%; OR, 0.80; 95% confidence interval, 0.75-0.86), were less likely to be prescribed methylphenidate, and were more commonly prescribed second line treatments such as dexamphetamine, amphetamine, or modafinil. No group difference was observed for atomoxetine. In adults with ADHD and coexisting ASD, methylphenidate was prescribed in lower daily doses over three years as compared to individuals with pure ADHD., Conclusions: The findings indicate that there are differences in the medical treatment of individuals with or without ASD. If these differences are due to different medication responses in ASD or due to other factors such as clinicians' perceptions of medication effects in patients with ASD, needs to be further studied.

Zetterqvist J, Asherson P, Halldner L, Långström N, Larsson H. Stimulant and non-stimulant attention deficit/hyperactivity disorder drug use: total population study of trends and discontinuation patterns 2006-2009. Objective: To explore the prevalence and discontinuation of dispensed medications for attention deficit/hyperactivity disorder (ADHD) drugs from 2006 to 2009. Method: A total population cohort of all individuals aged 6-45 years, alive and registered as residents in Sweden during any calendar year from 2006 to 2009 ( N = 5 149 791) included 41 700 patients dispensed with an ADHD drug (methylphenidate, atomoxetine, amphetamine, or dexamphetamine). The dispensing prevalence was calculated for each year, stratified on sex and age. A longitudinal analysis was also performed to compare the rates of treatment discontinuation across the strata. Results: The dispensing prevalence increased from 2.93 per 1000 in 2006 to 6.98 in 2009 (PR = 2.38, 95% CI = 2.34-2.43). The prevalence ratio (PR) was 3.40 for adults, 22-45 years old; 2.41 for adolescents, 15-21 years old; and 1.90 for children aged 6-14. The increase was also greater in women than in men (PR = 2.92 vs. 2.19). Patients aged 15-21 were the most likely to discontinue treatment; after 3 years and 11 months, 27% of those patients were still under treatment. Conclusion: From 2006 to 2009, the number of prescriptions dispensed for ADHD drugs increased substantially. The rate of treatment discontinuation in the age interval 15-21 is higher than expected considering the persistence rates of the disorder. [ABSTRACT FROM AUTHOR]