Prevalence and diagnostic stability of ADHD and ODD in Turkish children: a 4-year longitudinal study

BACKGROUND: This study was designed to assess the prevalence of Attention-Deficit/Hyperactivity Disorder (ADHD) and Oppositional Defiant Disorder (ODD) in a representative sample of second grade students from a country in a region where no previous rates are available (Turkey). The second aim is to evaluate the differences in ADHD and ODD prevalence rates among four different waves with one-year gap in reassessments. METHOD: Sixteen schools were randomly selected and stratified according to socioeconomic classes. The DSM-IV Disruptive Behavior Disorders Rating Scale (T-DSM-IV-S) was delivered to parents and teachers for screening in around 1500 children. Screen positive cases and matched controls were extensively assessed using the K-SADS-PL and a scale to assess impairment criterion. The sample was reassessed in the second, third and fourth waves with the same methodology. RESULTS: The prevalence rates of ADHD in the four waves were respectively 13.38%, 12.53%, 12.22% and 12.91%. The ODD prevalence was found to be 3.77% in the first wave, 0.96% in the second, 5.41% in the third and 5.35% in the fourth wave. Mean ODD prevalence was found to be 3.87%. CONCLUSIONS: The prevalence rates of ADHD in the four waves were remarkably higher than the worldwide pooled childhood prevalence. ADHD diagnosis was quite stable in reassessments after one, two and three years. A mean ODD prevalence consistent with the worldwide-pooled prevalence was found; but diagnostic stability was much lower compared to ADHD.