There has been an increase in the use of ADHD medication in several countries, raising concerns about potential overdiagnosis of ADHD and/or inappropriate prescription of ADHD medication. The aim of this study was to determine the prevalence of ADHD medication use over time in children, adolescents and adults across countries in Asia, Australia, North America, and northern and western Europe.
Patient-level electronic data (obtained between 1 January 2001 and 31 December 2015) were collected from 15 participating sites in 13 different countries and one Special Administrative Region across four regions.* The study population consisted of all individuals aged ≥3 years during the study period (please note: ADHD medications are licensed for the treatment of children with ADHD who are aged 6 years and older), who were grouped as follows: kindergarten/pre-school (3–5 years old); primary school (6–11 years old)†; secondary school (12–16 years old); older adolescents (17–18 years old); and adults (≥19 years old). Using the World Health Organization Anatomical Therapeutic Chemical (ATC) classification, records for prescribed medication, dispensed medication or insurance claims were used to identify medication use. Medication use was investigated regardless of whether a diagnosis of ADHD was made; exposure to medication was defined as the presence of a medication record at least once in the relevant study year.
Prevalence of ADHD medication use in children and adolescents (3–18 years old)
- Data were available from 154.5 million individuals. The overall pooled prevalence of ADHD medication use in children and adolescents was 1.95% (95% confidence interval [CI] 0.76–3.13) across all regions.
- The highest regional prevalence was in North America (4.48% [95% CI 2.86–6.10]) followed by northern Europe (1.95% [95% CI 1.47–2.44]). Asia and Australia (0.95% [95% CI 0.35–1.56]) and western Europe (0.70% [95% CI 0.31–1.10]) had the lowest pooled regional prevalence.
- In all regions, ADHD medication use in 3–12 year olds increased over time; the absolute increase per year ranged from 0.02% (France) to 0.26% (Sweden).
- Canada had the highest yearly increase in medication use, with mean increases of 45.11% (95% CI 43.50–46.71) per year, followed by Hong Kong, Taiwan, Finland, Denmark and Sweden. The lowest average increase per year was observed at the two sites in the US; 3.16% (95% CI 3.14–3.18) for US Medicaid and 2.83% (95% CI 2.80–2.86) for US MarketScan.
Prevalence of ADHD medication use in adults (≥19 years old)
- In adults, the overall pooled prevalence of ADHD medication use was 0.39% (95% CI 0.31–0.47).
- Similar to the prevalence in children and adolescents, the highest regional prevalence was in North America (1.42% [95% CI 1.29–1.54]), followed by northern Europe (0.47% [95% CI 0.31–0.62]), Asia and Australia (0.05% [95% CI 0.004–0.10]), and western Europe (0.03% [95% CI 0.01–0.04]).
- In all regions, ADHD medication use increased over time; the absolute increase per year ranged from 0.0006% (Hong Kong) to 0.12% (one site in the US).
- Asia and Australia had the highest yearly increase in medication use (25.06% [95% CI 17.65–32.46]), followed by northern Europe (18.81% [95% CI 10.74–26.87]) and western Europe (17.01% [95% CI 11.83–22.19]). Both sites in the US had the lowest average yearly increase in medication use (11.66% [95% CI 11.62–11.69] for US MarketScan and 14.30% [95% CI 14.22–14.38] for US Medicaid).
Prevalence of ADHD medication in males and females and type of treatment
- The overall male to female ratio of medication use across all countries was 2:1 and was greater in children than in adults (2.0–6.3:1 and 0.9–2.7:1, respectively).
- Of all of the individuals who used ADHD medication, >90% used methylphenidate in Hong Kong, Taiwan, Canada, Finland and Spain; the second most commonly used medication was atomoxetine in these countries. Approximately 75–90% of individuals in Japan, Denmark, Iceland, Norway, Sweden and the UK used methylphenidate, whereas only 59% and 45% of individuals used this treatment in Australia and at one of the sites in the US (US Medicaid), respectively. The most commonly used medication at US MarketScan was amfetamine (41%), followed by methylphenidate (34%) then lisdexamfetamine (21%).
The authors acknowledged that this study contained several limitations. For instance, although the authors used a common protocol between countries, there may be differences in the accuracy and generalisability of these data, as the datasets came from different sources. In addition, several ADHD medications are used off-label and therefore would not have been included in the study. Moreover, as a diagnosis of ADHD was not included, the authors could not examine the clinical characteristics of individuals using ADHD medication, and as exposure to medication over time was not taken into account, no conclusions can be drawn regarding medication adherence.
In concluding, the authors stated that to date this is the most comprehensive analysis of ADHD medication use in children, adolescents and adults across several global regions. The authors suggested that further research is needed to investigate the safety and effectiveness of short- and long-term ADHD medication use to help develop evidence-based guidelines.
Read more about global trends and prevalence in ADHD medication use here
*These regions included Asia and Australia (Australia, Hong Kong, Japan and Taiwan), North America (Canada and two sites in the US), northern Europe (Denmark, Finland, Iceland, Norway and Sweden) and western Europe (France, Spain and the UK)
†Data provided from Canadian sites only included children aged ≤11 years; therefore Canada was excluded from age-specific analyses for individuals aged ≥12 years
Raman SR, Man KKC, Bahmanyar S, et al. Trends in attention-deficit hyperactivity disorder medication use: a retrospective observational study using population-based databases. Lancet Psychiatry 2018; 5: 824-835.