Reduced body protein in children with spastic quadriplegic cerebral palsy

BACKGROUND: No studies have directly measured body protein or validated skinfold-thickness anthropometry and dual-energy X-ray absorptiometry (DXA) to assess body protein in children with spastic quadriplegic cerebral palsy (SQCP). OBJECTIVE: We aimed to measure and evaluate body protein and to determine whether skinfold-thickness anthropometry and DXA can predict body protein in children with SQCP. DESIGN: This was a cross-sectional study of 59 children (22 girls, 37 boys) aged 3.9-19.5 y with SQCP. The children underwent measurements of anthropometric indexes, lean tissue mass by DXA (LTM[subscript DXA]), and total body protein by neutron activation analysis (TBP[subscript NAA]). In addition, TBP was estimated from both skinfold-thickness anthropometry (TBP[subscript SKIN]) and DXA (TBP[subscript DXA]). The agreement of TBP[subscript SKIN] and TBP[subscript DXA] was tested against TBP[subscript NAA] by using Bland and Altman plot analysis. RESULTS: Height and weight SD scores (x ± SD: -3.1 ± 1.6 and -4.8 ± 5.3, respectively) were significantly lower than reference data in the children with SQCP (P < 0.001). TBP[subscript NAA] for age and height was low in the children with SQCP (P < 0.001): 56.1 ± 17.3% and 81.5 ± 15.7%, respectively, of the values predicted from control data. TBP[subscript SKIN] and TBP[subscript DXA] were both highly correlated with TBP[subscript NAA]: r = 0.90, P < 0.001, and r = 0.91, P < 0.001, respectively. Despite these significant correlations, agreement analyses showed wide variation of up to 33.3% of the mean for both methods. CONCLUSIONS: Body protein in children with SQCP is significantly reduced for age and height. Skinfold anthropometry and DXA show wide variation in estimation of body protein compared with NAA in this group of children.