Diagnostic performance of body mass index to identify excess body fat in children with cerebral palsy

AimTo assess the diagnostic performance of body mass index (BMI) cut-off values according to recommendations of the World Health Organization (WHO), the World Obesity Federation (WOF), and the German Society for Adiposity (DAG) to identify excess body fat in children with cerebral palsy (CP).

MethodThe present study was a monocentric retrospective analysis of prospectively collected data among children and adolescents with CP participating in a rehabilitation programme. Excess body fat was defined as a body fat percentage above the 85th centile assessed by dual-energy X-ray absorptiometry.

ResultsIn total, 329 children (181 males, 148 females) with CP were eligible for analysis. The mean age was 12years 4months (standard deviation 2y 9mo). The BMI cut-off values for overweight' according to the WHO, WOF, and DAG showed the following sensitivities and specificities for the prediction of excess body fat in our population: WHO: sensitivity 0.768 (95% confidence interval [CI] 0.636-0.870), specificity 0.894 (95% CI 0.851-0.928); WOF: sensitivity 0.696 (95% CI 0.559-0.812), specificity 0.934 (95% CI 0.898-0.960); DAG: sensitivity 0.411 (95% CI 0.281-0.550), specificity 0.993 (95% CI 0.974-0.999).

InterpretationBody mass index showed high specificity, but low sensitivity in children with CP. Thus, normal-weight obese' children with CP were overlooked, when assessing excess body fat only using BMI.