In the United Kingdom (UK), attention-deficit/ hyperactivity disorder (ADHD) affects around 5-8% of children and 2% of adults in the general population. The impact of untreated ADHD on day-to-day life is profound. Negative outcomes associated with ADHD include substance abuse/addictive behaviour, obesity, antisocial-behaviour, poor peer relationships, reduced social functioning, low self-esteem, poor academic/occupational performance, and traffic offences. In particular, patients with ADHD are at an increased risk of attempted suicide and four times more likely to die from suicide, even if comorbid psychiatric disorders are clinically treated. Pharmacologic therapies are useful for the management of core symptoms of ADHD and subsequent reduction of negative outcomes. However, recently, there have been concerns about a potential association between ADHD treatment and suicide-related events. Yet, few studies have addressed this issue directly.
Our study will use the Clinical Practice Research Datalink to compare the risk of suicide attempt events between periods of exposure of ADHD medication and unexposed periods amongst patients who use ADHD medication. The main outcomes that we will study include any forms of suicide attempt events.
If we find that ADHD medication is not related to increased risk of suicide attempt, our study will provide reassurance regarding the safety of this drug class in patients with ADHD. Given the increasing rates of ADHD in the UK, this study will have important policy, clinical, and public health implications.
We will conduct a population-based self-controlled case series study including all individuals aged ≥6 years who received at least 1 prescription for ADHD medication in the CPRD database between January 1, 1995 to December 31, 2020. Our objective will be to compare the risk of suicide attempt among patients treated with ADHD medication in periods of exposure to ADHD medication versus unexposed periods. Participants who were continuously exposed to the drug will contribute to consecutive exposure risk periods. We will determine the duration of exposure in the study period and calculate incidence rates for suicide attempt events in each of the exposure risk periods. In our analysis, we will estimate the incidence rate ratios of our outcomes using conditional Poisson regression. We will estimate the adjusted IRRs and their 95% confidence intervals for exposure overall and for each predetermined exposure risk periods.
Suicide attempt
Kenneth Man - Chief Investigator - University College London ( UCL )
Kenneth Man - Corresponding Applicant - University College London ( UCL )
Ian Wong - Collaborator - University College London ( UCL )
Li Wei - Collaborator - University College London ( UCL )
Wallis Lau - Collaborator - University College London ( UCL )
HES Admitted Patient Care;ONS Death Registration Data;Patient Level Index of Multiple Deprivation;Practice Level Index of Multiple Deprivation