# Critical appraisal of studies evaluating prevalence of attention deficit hyperactivity disorder

## TL;DR

This paper evaluates the quality of studies on ADHD prevalence, finding most to be at high risk of bias.

## Contribution

It introduces the use of the JBI critical appraisal tool for assessing ADHD prevalence study quality.

## Key findings

- 61.4% of ADHD prevalence studies were at high risk of bias.
- Only 6.9% of studies had a low risk of bias.
- Systematic reviews should include critical appraisal to ensure reliable data.

## Abstract

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder affecting an estimated 5–7% of children and adolescents and 2–5% of adults. However, prevalence rates in published studies vary widely, largely due to methodological differences. High-quality, accurate, prevalence data are essential for clinical decision-making and policymaking. However, these data have not been consistently documented in previous meta-analyses and systematic reviews.

To assess the methodological quality of studies reporting ADHD prevalence using the relevant critical appraisal tool.

Our previously published systematic review identified 103 studies reporting clinically confirmed ADHD prevalence. The studies were grouped by type and age of subjects, and 101 studies were evaluated for risk of bias using an adapted Joanna Briggs Institute (JBI) critical appraisal tool modelled on the Cochrane Risk of Bias-2 (RoB2) method.

The Joanna Briggs Institute (JBI) critical appraisal tool was found to be the most suitable for evaluating prevalence studies. Of the studies reviewed, 62 (61.4%) were at high risk of bias, and only seven (6.9%) had a low risk. Although one- and two-stage clinical study designs are of a higher quality, they are still often highly susceptible to bias.

The methodological quality of most ADHD prevalence studies is low. Systematic reviews must include critical appraisal to ensure the reliability of synthesised data. Accurate prevalence estimates are urgently needed in order to improve our understanding of the disease burden and enhance patient management.