HK data: No correlation between ADHD medication prescriptions and poisoning events

No significant correlation is observed between prescriptions of medications for attention deficit/hyperactivity disorder (ADHD) and poisoning cases involving ADHD medications in Hong Kong, a descriptive analysis has shown.

The number of ADHD medication prescriptions increased by 2.6-fold in Hong Kong between 2009 and 2019 (from 32,497 to 84,037). Because of inattentiveness, hyperactivity and impulsivity, ADHD patients are at higher risk of intentional or accidental poisoning. “Accordingly, we hypothesized that an increase in ADHD medication prescriptions would lead to an increase in the number of poisoning cases involving ADHD medications in Hong Kong,” wrote the researchers. [Hong Kong Med J 2023;29:224-232]

The researchers therefore analyzed trends and characteristics of poisoning events involving ADHD medications by retrieving data regarding ADHD medication–related poisoning cases from the Hong Kong Poison Information Centre and medication prescription records from the Clinical Data Analysis and Reporting System (CDARS).

A total of 72 relevant poisoning cases (male, 68.1 percent) were identified between 2009 and 2019, most of which occurred in the affected individual’s residence (n=51; 70.8 percent). Most cases involved a single ADHD medication (n=56; 77.8 percent), and the most common ADHD medication involved was methylphenidate (n=70; 95.9 percent).

“The exposure reason was intentional poisoning in 47 cases [65.3 percent], accidental poisoning in 20 cases [27.8 percent], and an adverse reaction in one case [1.4 percent],” reported the researchers. Overall, a minor effect or no adverse effect occurred in 63 cases (87.5 percent), a moderate effect occurred in five cases, and a major effect occurred in four cases.

“Most poisoning cases involving ADHD medications occurred in children and adolescents [n=48; 66.67 percent]. Intentional poisoning occurred in a much larger proportion of cases among older individuals,” the researchers pointed out.

Despite the increasing number of ADHD medication prescriptions, there was no upward trend in poisoning events involving ADHD medications between 2009 and 2019. “No statistically significant association was observed between ADHD medication prescription trends and poisoning events involving ADHD medications,” the researchers noted.

Of 66 poisoning cases with an accident and emergency (A&E) number matched to CDARS data, 40 cases (60.6 percent) occurred in patients with ADHD (median age, 14 years), and 26 cases (39.4 percent) occurred in individuals without ADHD (median age, 33 years).

Of note, higher rates of other psychiatric disorders, such as depression and anxiety, were observed in poisoning cases in individuals without ADHD. “These psychiatric disorders may increase the risk of intentional self-poisoning,” explained the researchers. “Appropriate interventions and/or social support for individuals with psychiatric disorders should be planned and implemented to reduce the risk of poisoning.”

Accidental poisoning events, which occurred in approximately 30 percent of poisoning cases involving ADHD medications, were mostly among individuals aged <12 years. “At least one-quarter of poisoning cases could be prevented by good medication storage strategies [and caregiver education],” pointed out the researchers. “Management and safe storage of ADHD medications should be strengthened in both ADHD and non-ADHD populations.”