[Factors affecting therapeutic effect of ADHD treated by optimal dose of methylphenidate]

To explore the therapeutic effect, security and influencing factors of methylphenidate titration program, try to find the potential predicting index of therapeutic effect.

This study was openly designed. The patients who were fit for DSM-IV diagnosis criteria of attention deficit hyperactivity disorder (ADHD) underwent systematic methylphenidate titration treatment until they attained the most optimal dose with best therapeutic effect and minimal side effects. The primary evaluative index of therapeutic effect was ADHD rating scale filled by teachers (ADHD-RS-IV), and secondary index included abbreviated Conners questionnaire filled by teachers, ADHD rating scale and Conners questionnaire filled by parents. The matching sample t analyses were used, then the differences of rating scale between pre and post treatment were compared. The potential influencing factors information of therapeutic effects including symptom severity degree when visiting, IQ, sensory integration capability and achievement of school etc. were collected. Finally, the correlation analysis was used for continuous variables and variance analysis for dichotomization variables to analyze and check the factors' influence of declining scores of behavior scale.

The final prescribed daily dose for patients who completed dose titration was (17.3+/-7.7) mg on average, computed by kilo bodyweight was (0.45+/-0.11) mg/(kg x d). All the scale scores between pre and post treatment were significantly different (the pre-treatment score of ADHD rating scale completed by teachers was 30.25+/-9.16, and post-treatment score were 19.87+/-10.03 ,P<0.001). Neither daily dose nor kilo bodyweight dose of methylphenidate had correlation with therapeutic effect. Among all the factors, symptom severity degree was positively correlated with therapeutic effect (r=0.437-0.567, P<0.01);the C factor of Wechsler Intelligence Scale had weak positive correlation with declining score of the teachers' scale (after controlling the symptom severity degree pre and post treatment, the coefficient of partial correlation r'=0.235-0.309, P<0.01); the patients with learning disorder had less declining score of teachers' rating scale (total score 7.35+/-7.67,inattention score 4.85+/-4.54,hyperactivity-impulsivity score 2.50+/-4.12) than those without learning difficulty (total score 12.33+/-10.42,inattention score 6.96+/-6.00, hyperactivity-impulsivity score 5.32+/-5.37,P<0.05);the amelioration of the hyperactivity and impulsivity scores of the parents' rating of children with vestibular equilibrium function disorders (6.34+/-5.72)was better than those without vestibular equilibrium function disorders (3.98+/-4.84,P<0.01),while the inattention scores were worse (for those with vestibular equilibrium function disorders 5.34+/-5.70,for those without vestibular equilibrium function disorders 7.43+/-5.51,P<0.05).

Systematic methylphenidate titration program is safe and effective for Han-Chinese children. The individual variation of therapeutic effect has no association with dose. The possible effecting factors include the symptom severity degree, C factor of Wechsler Intelligence Scale, learning difficulty and vestibular equilibrium function disorders.