Treatment for Attention Deficit Hyperactivity Disorder (ADHD) and the Risk of Poisoning in Children and Adolescents - Hong Kong Healthcare Big Data Analysis

Abstract

Background: Children and adolescents with attention deficit hyperactivity disorder (ADHD) are at higher risk of poisoning. Currently, there is limited data on the association between ADHD treatment and poisoning. Methods: Patients aged 5-18 years with methylphenidate (MPH) prescription and incident poisoning diagnosis between Jan 2001 and June 2020 were identified from the Hong Kong Clinical Data Analysis and Reporting System. A self-controlled case series study design was used to compare the incidence rate ratios (IRRs) of poisoning during different risk windows (30 days before the first MPH prescription, exposure periods within 30 days of the first prescription, and periods of subsequent exposure) compared to the reference window (other non-exposure periods). Results: 42,203 patients were prescribed ADHD medications in Hong Kong, of which 417 were included in the analysis. Compared to other non-exposed periods, a higher risk of poisoning was found in 30 days before the first prescription (IRR=2.64, 95% confidence interval [CI] 1.33 to 5.22), and exposure periods within 30 days of the first prescription (IRR=2.18, 95% CI 1.06 to 4.48), but not during prolonged exposure. However, compared with 30 days before the first prescription as well as exposure periods within 30 days of the first prescription, there was a lower risk during the subsequent exposure (IRRs=0.45 and 0.55, respectively). Conclusions: The risk of poisoning was higher shortly before and after the first MPH prescription and became lower during the subsequent prescription. Our results do not support an association between MPH treatment and increased risk of poisoning.