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[Children's relative age in class and medication for attention-deficit/hyperactivity disorder. A population-based
Julián Librero1, Roberto Izquierdo-María2, María García-Gil3
1Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana (FISABIO), Valencia, España; Red de Investigación en Servicios de Salud en Enfermedades Crónicas (REDISSEC), Valencia, España.
Insights
Younger children in the same school grade are more likely to be treated for attention-deficit/hyperactivity disorder (ADHD). This study found a 2.5 to 3 times higher prevalence of ADHD treatment in younger students.
Area of Science:
- Pediatrics
- Neurodevelopmental Disorders
- Public Health
Background:
- Previous international studies indicate younger children within the same grade are disproportionately treated for ADHD.
- This phenomenon, known as the "relative age effect," warrants investigation in diverse healthcare settings.
Purpose of the Study:
- To investigate the prevalence of attention-deficit/hyperactivity disorder (ADHD) treatment in relation to relative age within school grades in Spain.
- To determine if younger children in Spanish school grades exhibit a higher likelihood of receiving ADHD treatment.
Main Methods:
- An observational, cross-sectional study was conducted using prevalence data from November 2013.
- The study included 20,237 children aged 6-12 years from the Valencia Ministry of Health information systems.
- Multivariate models analyzed the prevalence ratio of ADHD treatment based on children's birth month within each grade.
Main Results:
- 1.73% of children were treated for ADHD, with higher rates in boys (2.70%) than girls (0.71%).
- ADHD treatment prevalence increased with age, in males, and notably in the youngest children (born later in the calendar year).
- Children born between August and December showed a 2.5 to 3 times higher prevalence of ADHD treatment compared to those born in January within the same grade.
Conclusions:
- Younger children, relative to their older classmates in the same grade, are significantly more likely to be treated for ADHD.
- Pharmacological treatments, including methylphenidate and atomoxetine, are more frequently prescribed to younger children identified with ADHD.
Background And Objective:
Previous studies in various countries have shown that the youngest school children in the same class-grade are more likely to be treated for attention-deficit/hyperactivity disorder (ADHD) than their older classmates. The aim of this study is to determine in the Spanish setting whether younger relative age children in each grade have a higher prevalence of treatment for ADHD.
Subjects And Methods:
Population, observational, cross-sectional study in a health department, using prevalence data (November 2013) of treatment for ADHD in children aged 6-12 years. Data was obtained from the information systems of the Valencia Ministry of Health and multivariate models were used to estimate the prevalence ratio of treatment according to the month of birth of children in each grade.
Results:
Twenty thousand two hundred and thirty-seven children were included of whom 1.73% were treated for ADHD (boys: 2.70%; girls: 0.71%) in October 2013. The prevalence of treatment increased with age, in males, and in youngest children (born in the last months of each year). In the multivariate analysis, the prevalence of treatment in the youngest children (born in the months of August to December) was 2.5 to 3 times higher than in their older classmates (born in January).
Conclusions:
The younger children relative to their classmates are more likely to be treated pharmacologically with methylphenidate and/or atomoxetine.
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Diagnostic Criteria and Symptoms
To diagnose ADHD, symptoms must manifest before age 12 and be evident across multiple settings.