ADHD drug treatment and risk of suicidal behaviours, substance misuse, accidental injuries, transport accidents, and criminality: emulation of target trials.
Level 3 - non-randomized controlled study
Target trial emulation using non-randomized national register cohort data
PubMed 40803836 · doi:10.1136/bmj-2024-083658
What was done
Target trial emulation using Swedish national register data from 2007 to 2020. The cohort included 148,581 individuals aged 6 to 64 years (median age 17.4 years; 41.3% female) with a newly diagnosed case of ADHD. Researchers compared those who initiated ADHD drug treatment within three months of diagnosis (n = 84,282; 56.7%, predominantly methylphenidate at 88.4%) against non-initiators, evaluating first and recurrent occurrences of suicidal behaviours, substance misuse, accidental injuries, transport accidents, and criminality over a two-year follow-up period.
What was found
ADHD drug initiation was associated with statistically significant reductions in first-event rates for four out of five outcomes: - Suicidal behaviours: weighted incidence rate 14.5 vs 16.9 per 1000 person years; adjusted incidence rate ratio (aIRR) 0.83 (95% CI 0.78 to 0.88). - Substance misuse: 58.7 vs 69.1 per 1000 person years; aIRR 0.85 (95% CI 0.83 to 0.87). - Transport accidents: 24.0 vs 27.5 per 1000 person years; aIRR 0.88 (95% CI 0.82 to 0.94). - Criminality: 65.1 vs 76.1 per 1000 person years; aIRR 0.87 (95% CI 0.83 to 0.90). - Accidental injuries were not significantly reduced for first events: 88.5 vs 90.1 per 1000 person years; aIRR 0.98 (95% CI 0.96 to 1.01). For recurrent events, medication was associated with significant reductions across all five outcomes: suicidal behaviours (aIRR 0.85, 95% CI 0.77 to 0.93), substance misuse (aIRR 0.75, 95% CI 0.72 to 0.78), accidental injuries (aIRR 0.96, 95% CI 0.92 to 0.99), transport accidents (aIRR 0.84, 95% CI 0.76 to 0.91), and criminality (aIRR 0.75, 95% CI 0.71 to 0.79).
Why it matters
This study provides real-world evidence from an entire national population that early initiation of ADHD medication confers broad protective benefits against severe adverse behavioral and safety outcomes over two years.
Limits
As an observational register-based study, residual confounding by indication and unmeasured clinical severity cannot be completely ruled out despite target trial emulation methodology. Findings reflect Swedish healthcare and justice registries and may not fully generalize to other health systems. Actual patient medication adherence could not be directly verified, and follow-up was limited to two years.
Cited by
- supports Treating ADHD with medication reduces the risk of subsequent substance abuse compared to leaving ADHD untreated.