Diagnostic accuracy of referral criteria for head circumference to detect hydrocephalus in the first year of life.

Background: Increased head circumference is often the first and main sign leading to the diagnosis of hydrocephalus. Our aim is to investigate the diagnostic accuracy of referral criteria for head circumference to detect hydrocephalus in the first year of life.

Methods: A reference group with longitudinal head circumference data (n = 1938) was obtained from the Social Medical Survey of Children Attending Child Health Clinics study. The case group comprised infants with hydrocephalus treated in a tertiary pediatric hospital who had not already been detected during pregnancy (n = 125). Head circumference data were available for 43 patients. Head circumference data were standardized according to gestational age-specific references.

Results: Sensitivity and specificity of a very large head circumference (>2.5 standard deviations on the growth chart) were, respectively, 72.1% (95% confidence interval [CI]: 56.3-84.7) and 97.1% (95% CI:96.2-97.8). These figures were, respectively, 74.4% (95% CI: 58.8-86.5) and 93.0% (95% CI:91.8-94.1) for a large head circumference (>2.0 standard deviation), and 76.7% (95% CI:61.4-88.2) and 96.5% (95% CI:95.6-97.3) for a very large head circumference and/or a very large (>2.5 standard deviation) progressive growth of head circumference.

Conclusions: A very large head circumference and/or a very large progressive growth of head circumference shows the best diagnostic accuracy to detect hydrocephalus at an early stage. Gestational age-specific growth charts are recommended. Further improvements may be possible by taking into account parental head circumference.