IntroductionAttention deficit hyperactivity disorder (ADHD) is one of the most common neurodevelopmental paediatric disorders and persists into adulthood, although it is frequently underdiagnosed and underrecognized in adult populations. In this context, the prevalence of pharmacologically treated individuals diagnosed with ADHD represents an important quality indicator for ADHD management.AimTo estimate the pooled prevalence of pharmacologically treated individuals with ADHD in different age groups in Europe and worldwide.MethodsA comprehensive search of PubMed/MEDLINE was conducted to identify relevant articles published up to October 4, 2024. The present systematic review and meta-analysis examined ADHD prevalence using clinically confirmed diagnoses and treatment data from official records. The exclusion criteria included studies that lacked clinical confirmation of ADHD and/or relied exclusively on parental reports for diagnostic or medication information. The prevalence of pharmacologically treated individuals with ADHD was calculated as a percentage, with a 95% confidence interval (CI). A meta-analysis was performed in R using a random-effects model. Heterogeneity was calculated using I². Prediction intervals were additionally computed to reflect the expected range of prevalence in future studies. Risk of bias was assessed for all included studies using a standardized, previously published methodology. The study was prospectively registered in PROSPERO (CRD42020200220) and adhered to the PRISMA guidelines for systematic review and meta-analysis (2020).ResultsThe systematic review identified 13 studies (12 studies included in the meta-analysis) with substantial variation in age-specific reporting. The pooled prevalence of pharmacologically treated ADHD was 73.4% (95% CI: 63.4–81.5), with extremely high between-study heterogeneity and wide 95% prediction interval (29.6%–94.5%), reflecting substantial variation across settings. The pooled prevalence estimate should be interpreted with caution due to substantial between-study heterogeneity and is not intended for direct clinical inference. Geographic analyses revealed no significant variation across countries. Sex-stratified analyses showed no significant difference between males and females, although point estimates were slightly higher in males.ConclusionThe prevalence of pharmacological treatment among individuals with ADHD appears to vary across age groups and settings Overall, findings indicate substantial variation in pharmacological treatment of ADHD by age, with consistently high heterogeneity limiting the precision of pooled estimates.Systematic review registrationhttps://www.crd.york.ac.uk/PROSPERO/, identifier CRD42020200220.
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