BioMeasure Youth: An Electronic Measure
of Height, Weight and BMI
D. Sinha, M. Mason, K.K. Christoffel, Children’s
Memorial Hospital
Background
Childhood obesity in the U.S. is increasing.
Body mass index (BMI) is an
important tool for detecting obesity and monitoring adiposity. The
current 'gold standard' for
obtaining height (ht) and weight (wt) is manually, using standardized
methods. An accurate
ht/wt/BMI measuring device could save staff time and allow tracking
of large numbers of
children in community settings. The Biomeasure Youth (BY) is such a
device.
Objective
We evaluated the validity and reliability of the
BY.
Methods/Design: Kindergarten and grade 1 students at Namaste Charter
School were recruited
for a separate study. Research nurses visited the school and measured
height (3 times) and
weight (1 time) on manual standing scales. The children also had
2 measurements by BY on the
same day. We compared the mean heights, weights and BMI by the nurses
with the BY and the
two BY measures using Pearson correlation.
Results
69 children were
recruited (64% male, M and 68.1% Hispanic). The mean age was 6.0
years (SD +0.6). Results are shown in the Table.
Table 1: Results
| Measure |
Nurse (SD) |
BY (SD) |
R |
Δ |
| Mean weight (kg) M |
24.5 (6.7) |
24.5 (6.7) |
1.00 |
0 |
| Mean weight (kg) F |
22.6 (4.3) |
22.7 (4.3) |
1.00 |
0.1 |
| Mean height (cm) M |
117.0 (7.6) |
115.4 (8.5) |
0.91 |
1.6 |
| Mean height (cm) F |
114.7 (6.6) |
114.0 (7.0) |
0.98 |
0.7 |
| Mean BMI- M |
17.6 (3.0) |
18.2 (3.6) |
0.86 |
0.6 |
| Mean BMI- F |
17.1 (2.1) |
17.3 (2.1) |
0.98 |
0.2 |
The subjects' mean BMI was
at the 90th percentile (boys) and 85th percentile (girls). BY
overestimated wt and BMI underestimated ht. The mean error between
2 measurements of
the BY was 0.11 kg, 0.64 cm and 0.2 for BMI. The sensitivity of the
BY for detecting 'overweight'
children was 100%, with specificity 96%. For detection of the 'at
risk and overweight' group, the
sensitivity was 96.6% and specificity 87.5%. For underweight children,
the sensitivity was 25%
and specificity 100%.
Conclusions
The ht and BMI differences between
the nurses and the BY machine suggest that the current
model of this device is not accurate enough for routine use in
medical facilities or very suitable as a screen for overweight
children in the community setting.
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