PREDICTORS OF WEIGHT-LOSS IN CHILDREN WITH ATTENTION-DEFICIT HYPERACTIVITY DISORDER TREATED WITH STIMULANT MEDICATION

Objective. A retrospective study was under taken to examine predictors of weight loss in children with attention deficit hyperactivity disor der (ADHD) treated with stimulant medication. Design. Children diagnos ed with ADHD and treated with methylphenidate hydrochloride (MPH) or d extroamphetamine sulfate (DEX) for at least 5 months were identified b y retrospective chart review. Analyses were performed on 32 children ( 29 boys) treated with MPH and 28 children (25 boys) treated with DEX. Variables examined included pretreatment weight, pretreatment body mas s index (BMI), duration of treatment, total daily dose, and weight-adj usted dose. Results. The MPH-treated group was initially seen at a mea n age (+/- standard deviation) of 7.5 years (+/-2.1). Mean duration of follow-up was 11.2 months (+/-3.8). Mean total daily dose was 25.5 mg (+/-8.2) and mean weight-adjusted dose was 1.0 mg/kg/day (+/-.5). Mea n change in weight as expressed in z scores was -0.4 SD (+/-.7). The D EX-treated group was initially seen at a mean age of 9.3 years (+/-2.7 ). Mean duration of follow-up was 10.8 months (+/-4.1). Mean total dai ly dose was 14.9 mg (+/-8.2) and mean weight-adjusted dose was .5 mg/k g/day (+/-.3). Mean change in weight was -0.6 SD (+/-.6). Although the MPH group was younger than the DEX group, there were no between-group differences in weight or height either before treatment or at follow- up when adjusted for age and gender. Using linear regression analysis, significant correlations were found between pretreatment weight and c hange in weight for both the MPH-treated group (r = .63) and the DEX-t reated group (r = .47). Stepwise multiple-regression analysis indicate d that pretreatment age, weight-adjusted dose, and duration of follow- up did not significantly contribute to the variance in change of weigh t for either the MPH- or DEX-treated groups. To adjust for height, cha nges in BMI were also analyzed. For both medication groups, no differe nces were found between the heavier (BMI greater than or equal to 50%) and thinner (BMI <50%) children in duration of followup, total daily dose, or weight-adjusted dose. When the medication groups were combine d, a greater proportion of heavier children experienced a decease rela tive to their predicted BMI compared with thinner children (80% vs 52% ). Comparisons of mean BMI slopes revealed that the heavier group expe rienced an absolute decrease in their BMI (-.139) in contrast to the t hinner group (+.014) (t = 2.70). Conclusions. Pretreatment weight, adj usted for age, gender, and height, is a significant predictor of weigh t loss in children with ADHD treated with either MPH or DEX. In contra st, pretreatment age, duration of treatment, and weight-adjusted dose were not found to be significant predictors.