Cross-cultural reliability and validity of ADHD assessed by the ADHD Rating Scale in a pan-European study

OBJECTIVES: To provide psychometric information on the Attention-Deficit/Hyperactivity Disorder (ADHD) Rating Scale-IV (ADHD-RS-IV) in a large population of children with ADHD. METHODS: Patients aged 6-18 years (n=1,478 in baseline analysis) were rated by 244 physicians on the ADHD-RS-IV based on a semi-structured interview with the patient's parent. Physicians additionally rated functional impairment (CGAS) and health status (CGI-S), and parents rated their child's behavioural and emotional problems (SDQ) and quality of life (CHIP-CE). RESULTS: Inattention and hyperactivity-impulsivity as dimensions of ADHD were replicated. 3-factor solutions reflecting the ICD-10 definition, with hyperactivity, impulsivity and inattention as separate dimensions were extracted in some national sub-samples and in separate analyses for boys and younger children.Good internal consistencies, strong country effects and small effects of age were found. Based on ADHD-RS-IV, 88.5% of patients met the criteria for any ADHD diagnosis. Correlations between ADHD-RS-IV and measures of functional impairment were low but statistically significant. The correlations with SDQ and CHIP-CE scales confirm the convergent and divergent validity of ADHD-RS-IV. CONCLUSIONS: Impressive evidence for the cross-cultural factorial validity, internal consistency as well as convergent and divergent validity of ADHD-RS-IV was found. ADHD can be assessed reliably and validly in routine care across Europe. The ICD-10 3-factor model seems to be less robust than the DSM-IV 2-factor model, but may be a good description for special populations (boys, younger children).