[Estimation of the prevalence of attention deficit hyperactivity disorder among the standard population on the island of Majorca].

AIM: To determine the rate of prevalence of attention-deficit/ hyperactivity disorder (ADHD) in children of school age (6-11 years) in the Island of Mallorca. SUBJECTS AND METHODS: The epidemiological study was conducted using a community sample extracted by means of multi-stage stratified sampling according to areas (rural, city and touristy) and schooling (public, private and concerted) and consisted in 1,509 children of both sexes. The ADHD Rating Scales-IV (ADHD RS-IV) for home and school setting were used to collect data. The optimal approach to do a diagnostic evaluation, according with the literature, was using a cut-off point of 90 centil.
RESULTS: The estimated prevalence of ADHD was 4.57% (CI at 99%: 3.0-5.8%) and we also obtained 1.26% for the hyperactive subtype, 1.06% for the disattentional subtype, and 2.25% for the combined subtype. Contrary to what was expected, prevalence was higher for females but no statistically significant. There were no statistically significant differences between levels, schools or areas.
CONCLUSIONS: The estimates for prevalence found in this study are consistent with those reported in the literature (between 3-5%). Using the ADHD rating scale which has different cut-off point regarding age, sex and setting and the fact that it was a poblational based study could explain the higher prevalence in the females. We propose a normalization of the scales in our area in other to confirm our findings.