The prevalence of ADHD medication use has increased over time among adults and children between 2001 and 2015, according to study data involving more than 154 million people from 14 countries published in The Lancet Psychiatry.
The findings also showed that despite this increase, prescription rates for ADHD vary by region and lag behind diagnosis rates in many countries.
“Researchers have never examined ADHD medication use across this many countries,” Sudha R. Raman, PhD, assistant professor at Duke University School of Medicine, told Infectious Diseases in Children. “We felt that estimates of the trends of ADHD medication use over time and across countries are needed to guide research about the safety and effectiveness of ADHD medications in children and adults. Unlike other studies, we used a common protocol approach to reduce much of the study variability that hindered previous estimates of ADHD medication use.”
Researchers conducted a retrospective, observational study using population-based databases from 13 countries and one special administrative region to determine the prevalence — both regional and national — of ADHD medication use in children and adults aged 3 years or older from 2001 through 2015.
In total, 154.5 million individuals were included in the study.
Over the study period, an average of 2% of children and 0.4% of adults were given at least one prescription for an ADHD medication, the researchers said. Regional prevalence was highest in the United States, with an estimated 4.5% of children and 1.4% of adults using ADHD drugs, and lowest in Western Europe. In most countries, methylphenidate was the most commonly used ADHD medication, and amphetamine was the most common treatment for privately insured U.S. patients.
“Using data from real world sources, rather than clinical trials, we found that the prevalence of children and adults who have used ADHD medication is increasing in all countries,” Raman said.
According to the researchers, the absolute increase in ADHD medication use prevalence per year ranged from 0.02% to 0.26%. Among adults, results showed that the absolute increase in ADHD medication use prevalence per year ranged from 0.0006% to 0.12%. In 2010, ADHD drug use prevalence varied between 0.27% (France) and 6.69% (U.S., publicly insured) in children and between 0.003% (Japan) and 1.48% in adults (U.S., privately insured).
Youth in Canada experienced the biggest increase in ADHD medication use, with average increases of more than 45% per year. In adults, Japan had the most rapid increases than other countries, with average increases of 76% per year. In comparison, the rate of increase in the U.S. was slower than that of other countries in both children and adults, with increases around 3% and 13% each year, respectively, according to the results.
“The large differences between absolute estimates of ADHD medication use by country suggests that there is wide variation in how ADHD is treated,” Raman said. “This is especially relevant for adults with ADHD since most research has been about ADHD medication in children. For clinicians, these results support the consistent use of evidence-based guidelines in practice.”
Despite these large increases observed globally, overall medication use remains lower than ADHD diagnosis rates, the findings revealed. The high variation across and within regions suggests the clinical approach to treat ADHD differs greatly.
“What’s especially important is our finding that the rates and type of drug treatment prescribed appears to depend largely on where you live,” co-researcher Ian C.K. Wong, PhD, of the University of Hong Kong, said in a press release. “There is a need for monitoring medication safety and effectiveness in exposed populations, particularly in adults.”
Every cultural and geopolitical region has its own set of factors that affect ADHD medication treatment referral and prescribing behaviors, Margaret H. Sibley, PhD, from Florida International University, wrote in a related editorial.
“There is an urgent need to refine evidence-based guidelines for stimulant medication. This mission extends beyond ADHD,” she wrote. “Researchers should address pressing questions, including the following: which sources of cognitive dysfunction (eg, illness, sleep difficulties, stress, trauma, low intelligence quotient, high demands, or fatigue) are appropriate for stimulant prescription and under which circumstances is it appropriate to prescribe stimulants to cognitively healthy individuals.” – by Savannah Demko
- Raman SR, et al. Lancet Psychiatry. 2018;doi:10.1016/S2215-0366(18)30293-1.
- Sibley MH. Lancet Psychiatry. 2018;doi:10.1016/S2215-0366(18)30317-1.
Disclosures: Raman reports receiving grants from GlaxoSmithKline. Please see the study for all other authors’ relevant financial disclosures. Sibley reports no relevant financial disclosures.