Age-dependent diagnostic performance of mid-upper arm circumference Z-score in pediatric neurology: A multicenter study with a cerebral palsy subgroup.

BACKGROUND

Malnutrition is a common but frequently underrecognized comorbidity in children with neurological disorders. Accurate nutritional assessment is often challenging in pediatric neurology practice due to motor impairment, skeletal deformities, and unreliable height and weight measurements. Mid-upper arm circumference Z-score (MUAC-Z) has emerged as a practical anthropometric alternative; however, its age-dependent diagnostic performance in neurologically affected children remains insufficiently defined.

OBJECTIVE

To evaluate the age-specific diagnostic accuracy of MUAC-Z for detecting malnutrition in a large pediatric neurology outpatient cohort and in a predefined subgroup of children with cerebral palsy (CP).

METHODS

This multicenter, analytical cross-sectional study included 3668 children aged 6 months to 19 years attending pediatric neurology outpatient clinics, including 242 children with CP. Participants were stratified into two age groups (6-60 months and 5-19 years). Malnutrition was defined as weight-for-age Z-score (WAZ) < -2 in children under 5 years and body mass index-for-age Z-score (BMI-Z) < -2 in older children. Anthropometric measurements, laboratory parameters, and enteral feeding status were recorded. Diagnostic performance of MUAC-Z was assessed using receiver operating characteristic (ROC) curve analysis.

RESULTS

MUAC-Z demonstrated moderate diagnostic accuracy in children aged 6-60 months (AUC 0.772), with marked variability across early childhood subgroups. In contrast, MUAC-Z showed excellent diagnostic performance in children aged 5-19 years (AUC 0.907). In the CP subgroup, malnutrition prevalence was substantially higher across all indices. MUAC-Z showed limited accuracy in CP children under 5 years (AUC 0.668) but good diagnostic performance in those aged 5-19 years (AUC 0.774). Older malnourished children, particularly those with CP, exhibited more frequent laboratory abnormalities consistent with chronic nutritional impairment.

CONCLUSIONS

The diagnostic utility of MUAC-Z in pediatric neurology is strongly age-dependent. MUAC-Z represents a reliable and practical screening tool in school-aged children and adolescents, including those with cerebral palsy, while its use in early childhood should be complementary to conventional anthropometric indices.