Screening of hydrocephalus in infants using either WHO or population-based head circumference reference charts.

Aim: The aim was to compare the performances of the World Health Organization (WHO) and population-based (PB) references in the screening for hydrocephalus in infants aged <2 years.

Methods: We collected 341 longitudinal head circumference (HC) measurements of hydrocephalic infants and 120 181 measurements of 15 145 healthy infants from primary care. The measurements were converted into z-scores, and a new screening parameter, change in HC standard deviation score (SDS) over time (ΔHC SDS), was calculated. Comparisons were made using receiver operating characteristics analysis and linear mixed models.

Results: The mean HC SDS was 3.5 and the mean HC SDS was 2.9 in the hydrocephalic infants, and in healthy children, those numbers were 1.0 SDS and 0 SDS , respectively. The best screening accuracy was obtained with the PB reference in combination with the ΔHC SDS parameter (AUC 0.89). The accuracy of the WHO standard could be improved to a similar level by customising the screening cut-offs of HC SDS according to the population and combining screening parameters.

Conclusions: Auxology alone was not sufficient for the screening of hydrocephalus. The WHO standard should be validated in the population, and population-specific cut-offs for normality defined before its introduction.