Aim: To compare the prevalence of attention deficit disorder and hyperactivity disorder (ADHD) using different diagnostic criteria (DSM-IV-TR versus ICD-10) and two specific scales based on DSM IV (ADHD-IV Rating Scales and SNAP-IV p90) in school-age children (6-12 years).
Patients and method: . A population-based study applying stratified multistage sample design (by courses), proportional to the type of school (public, private and enterd) and demographic areas (rural, city). From a target population of approximately 30 000 subjects a sample of 1509 children.
Results: The prevalence rates of ADHD were within the expected range: 3.6% (95% CI = 2.6-4.6%) using DSM-IV criteria, 1.2% (95% CI = 0.6-1.8%) using the ICD-10, 4.6% (95% CI = 3.5-5.7%) using ADHD Rating Scales-IV with a cut-off of 90 percentile 4.11% (95% CI = 3.2-5.1%) using the scale SNAP-IV. However, we found some differences in reference to gender and subtype according to the criteria and instrument used.
Conclusions: We propose to use standard scales, scale by age, sex and evaluator that includes maturation and sociocultural factors help us draw conclusions about the true prevalence of ADHD.