The table below gives some hypothetical data on age, height and weight of five boys between 2 and 5 years old.
|Anthropometric data for 5 boys
If you have the WHO Anthro package you can use their anthropometric calculator to calculate Z-scores (and percentiles assuming a normal distribution) with the new WHO reference values. The figure below shows the output of this package for the data on Saddam - the mid-upper arm circumference input in this case was 14 cm.
If you have the EpiInfo package, this gives Z-scores based on the old NCHS/WHO reference values. Note the results are rather different. The new reference values give Saddam a weight-for-height Z-value of − 1.28, whilst the old values give him a Z-value of − 0.91. These differences have caused some consternation amongst aid workers directly involved in assessing malnutrition (see references below), but should perhaps just serve as a warning that all such approaches have a large margin of error!
Results for weight for height, height for age, and weight for age for all five boys using the old NCHS/WHO reference values are given below:
|Anthropometric data and Z-scores
| − 1.48
| − 0.81
| − 1.99
Remember the two key scores to look at are weight for height (for wasting) and height for age (for stunting). Weight for age shows the combined effects of these two processes. Clearly George is suffering from wasting, and Tony from stunting. Saddam is borderline for malnutrition when you consider the combined effects of stunting and wasting.