Pediatric Idiopathic Intracranial Hypertension: Age, Gender, and Anthropometric Features at Diagnosis in a Large, Retrospective, Multisite Cohort

Abstract

Purpose: To examine anthropometric and maturational characteristics at diagnosis in pediatric idiopathic intracranial hypertension (IIH).

Design: Retrospective, international, multisite study.

Participants: Pediatric patients (2-18 years of age at diagnosis) with IIH.

Main outcome measures: Body mass index (BMI), height, and weight Z-scores; sexual maturation.

Methods: Cases of IIH were identified retrospectively based on diagnostic code, pediatric neuro-ophthalmologist databases, or both and updated diagnostic criteria (2013) were applied to confirm definite IIH. Anthropometric measurements were converted into age- and gender-specific height, weight, and BMI Z-scores CDC 2000 growth charts. When available, sexual maturation was noted.

Results: Two hundred thirty-three cases of definite IIH were identified across 8 sites. In boys, a moderate association between age and BMI Z-scores was noted (Pearson's correlation coefficient, 0.50; 95% confidence interval [CI], 0.30-0.66; P < 0.001; n = 72), and in girls, a weak association was noted (Pearson's correlation coefficient, 0.34; 95% CI, 0.20-0.47; P < 0.001; n = 161). The average patient was more likely to be overweight at diagnosis at age 6.7 years in girls and 8.7 years in boys, and obese at diagnosis at age 12.5 years in girls and 12.4 years in boys. Compared with age- and gender-matched reference values, early adolescent patients were taller for age (P = 0.002 in girls and P = 0.02 in boys). Data on Tanner staging, menarchal status, or both were available in 25% of cases (n = 57/233). Prepubertal participants (n = 12) had lower average BMI Z-scores (0.95±1.98) compared with pubertal participants (n = 45; 1.92±0.60), but this result did not reach statistical significance (P = 0.09).

Conclusions: With updated diagnostic criteria and pediatric-specific assessments, the present study identifies 3 subgroups of pediatric IIH: a young group that is not overweight, an early adolescent group that is either overweight or obese, and a late adolescent group that is mostly obese. Data also suggest that the early adolescent group with IIH may be taller than age- and gender-matched reference values. Understanding these features of pediatric IIH may help to illuminate the complex pathogenesis of this condition.

Figure 1

Dot distribution plots showing the relationship between body mass index (BMI) Z-score and age at diagnosis of pediatric idiopathic intracranial hypertension (IIH). In both girls and boys, there is a positive relationship between BMI Z-score and age at diagnosis of definite pediatric IIH. Specifically, in boys, a moderate association was noted (Pearson’s correlation coefficient, 0.50; 95% confidence interval [CI], 0.30–0.66; P < 0.001; n = 72), and in girls, a weak association was noted (Pearson’s correlation coefficient, 0.34; 95% CI, 0.20–0.47; P < 0.001; n = 161). In both groups, the circles represent data obtained from individual participants, whereas the color of the circle represents pubertal status (“missing” indicates that pubertal information was not available). The line represents the results of a linear regression of BMI-Z with 95% CIs of the mean (Stata software; Stata Corp, College Station, TX). Horizontal reference lines indicate the Centers for Disease Control and Prevention (CDC)-defined BMI Z-scores for overweight and obesity features in the pediatric population. The thin arrows indicate overweight thresholds and thick arrows indicate obese thresholds. The overweight threshold indicates the intersection between the plotted linear regression relationship and the BMI Z-score of 1.04 (CDC definition of overweight). The obese threshold indicates the intersection between the linear regression relationship and the BMI Z-score of 1.64 (CDC definition of obese). The overweight threshold occurred at 6.7 years in girls and 8.7 years in boys. The obese threshold occurred at 12.5 years in girls and 12.4 years in boys.

Figure 2

Dot distribution plots showing the distinct differences in anthropometric features seen between defined age categories in participants with pediatric idiopathic intracranial hypertension (IIH). Distribution plots illustrate body mass index (BMI), weight, or height Z-scores, seen in defined age categories of participants with pediatric IIH. The age cutoffs were defined empirically, using the regression analysis in Figure 1. For girls, the categories were young children younger than 7 years, early adolescents between 7 and 12.5 years of age, and older adolescents 12.5 years of age or older. For boys, the categories were young children younger than 8.5 years, early adolescents between 8.5 and 12.5 years of age, and older adolescents 12.5 years of age or older. In both boys and girls with pediatric IIH, (A) BMI Z-scores and (B) weight Z-scores increased in older age categories (P = 0.0001 in girls and P < 0.0001 in boys, analysis of variance of BMI Z-scores; and P = 0.0015 in girls and P < 0.0001 in boys, analysis of variance of weight Z-scores). C, In girls and boys with pediatric IIH, only height Z-scores measured in the early adolescent categories were higher than the age- and gender-matched hypothesized values. Statistical comparisons used 1-way t test analyses to compare mean Z-scores against a hypothesized mean Z-score of 0.00 (e.g., age- and gender-matched normative data). In girls, P = 0.28 in those younger than 7 years, P = 0.004 in those 7 to 12.5 years, and P = 0.45 in those 12.5 years of age or older. In boys, P = 0.35 in those younger than 8.5 years, P = 0.03 in those 8.5 to 12.5 years, and P = 0.71 in those 12.5 years of age or older. In (A), (B), and (C), circles represent individual data points, whereas the color of the circle indicates pubertal status (“missing” indicates that pubertal information was not available). Boldface, dashed lines indicate mean values.