Girls with attention deficit hyperactivity disorder (ADHD) who were prescribed osmotic-release oral system methylphenidate hydrochloride (OROS-MPH) and pediatric patients who had concomitant atomoxetine or hypnotic therapy were at increased risk for poor OROS-MPH adherence. These findings from a retrospective survey were published in Scientific Reports.

OROS-MPH was prescribed progressively more often in Japan from 0.003% in 2007 to 0.23% in 2016. Data from JMDC Inc., which collects claim information from occupation-based health insurance agencies in Japan and covers about 2.5% of the Japanese population, were analyzed for this study. Outpatients (aged 6-17 years; N=1353) prescribed OROS-MPH between 2007 and 2015 were assessed for adherence. Discontinuation of treatment was defined as more than a 3-month gap in OROS-MPH prescriptions.

Of the patients, 84.3% were boys, 80.1% were between 6 and 12 years of age at first prescription, and 48.3% were prescribed a low dose (<18 mg). The mean medication possession ratio (MPR) among pediatric patients prescribed OROS-MPH was 0.51 (±0.32).

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A small proportion of patients (8.6%) had no gap in their OROS-MPH prescriptions, but 51.9% had a gap of more than 3 months. Fewer patients with a gap of more than 3 months resumed their medication (17.9%) compared with those who had a gap of less than 2 months (95.7%).

Poorer OROS-MPH adherence was observed among girls (OR, 0.5650; 95% CI, 0.414-0.773; P =0.0000), and those prescribed atomoxetine (OR, 0.3760; 95% CI, 0.273-0.517; P =0.0000) or hypnotics (OR, 0.5360; 95% CI, 0.291-0.985; P =.0450). Adherence was observed to increase with OROS-MPH dose (18-27 mg: OR, 1.9860; 95% CI, 1.554-2.536; P =0.0000; ³27 mg: OR, 2.4990; 95% CI, 1.731-3.608; P =0.0000).

The investigators did not find a relationship between ADHD severity and medication adherence. It remains unclear whether adverse effects from concomitant treatment with hypnotics or atomoxetine may be contributing to the poor adherence among these patients.

This study may not be generalizable because the study data were sourced through a private insurance company and were likely biased toward people of higher socioeconomic status.

These findings indicated that girls and pediatric patients prescribed concomitant treatment with hypnotics or atomoxetine were at increased risk for poor OROS-MPH adherence. Clinicians should be aware of these risk factors so early interventions may be taken for patients at higher risk.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please refer to the original reference for a full list of authors’ disclosures.


Ishizuya A, Enomoto M, Tachimori H, et al. Risk factors for low adherence to methylphenidate treatment in pediatric patients with attention‑deficit/hyperactivity disorder. Sci Rep. 2021;11(1):1707. doi:10.1038/s41598-021-81416-z