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various intracranial pressure (ICP) parameters for high pressure
hydrocephalus patients are utilized to detect various shunt faults in their early
stages, as well as, to monitor the effect of such faults on shunt performance.
A method was proposed to predict the time required for ICP to be abnormal and
for the valve to reach full blockage condition. Furthermore, an auto valve
schedule updating method is proposed and used to temporarily deal with detected
faults until the patient is checked up by his/her physician. The proposed
algorithms were evaluated using numerical simulation.
Aims: This study compares the WHO (2007) and the National Health Examination Survey (NHANES III) reference intervals and investigates the differences when applied on a Canadian cohort of older children and adolescents. Methods: We calculated height, weight and BMI z-scores of 4375 consecutive patients (1993 female, 45.6%) aged 5 - 20 years attending outpatient clinics at a single tertiary care centre using reference data of the latest NHANES (III) survey and the WHO (2007) growth charts. To address age dependency, data was stratified into age groups. Results: Using the NHANES III reference intervals, medians of weight (+0.46), height (+0.29) and BMI z-scores (+0.46) were significantly non-zero. The WHO (2007) growth charts yielded medians of +2.05, +0.32, +0.53 for weight, height and BMI z-scores respectively, all significantly non-zero. When comparing both growth charts, Canadian children had significantly different weight and BMI z-scores (p < 0.0001) with WHO growth charts whereas height z-score did not differ. Obesity rates (BMI z-score > 95th percentile) doubled from 8.6% to 16.0%. A significant age dependency was observed with higher WHO (2007) weight z-scores (>7 years) and higher BMI z-scores (7 to 13 years) and no significant difference was observed for height z-scores across all age groups. Gender differences were observed for weight z-scores (>9 years) and BMI (males: 9 - 11 years, p = 0.0118; 11 - 13 years, p = 0.0069) whereas no significant difference was found in height z-scores across all age groups. Conclusion: Our results reveal substantial differences between both reference populations and thus interpretation needs be done with caution, especially when labelling results as abnormal.