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Données anthropométriques des enfants 6-24 en provenance d'Afrique utilisant Stata

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Hyun Ju Lee

Normal user

2 Aug 2017, 11:33

Hi,
I am using Stata for analysis my data from Africa focusing on children aged from 6 to 24 months and need to calculate MUAC-for-age z-score and WAZ.

I found there are differences between zscore06 and zanthro. From my understanding of them, zscore06 is only based on WHO child growth standard 2006 and zanthro is based on WHO, UK and other countries. Therefore, I think using zscore06 is better for my study population, but it did not cover calculating MUAC-for-age z-score.

I want to ask if you know exact difference between zanthro and zscore06 and if anyone knows, what do you think what might be better for my population. I also found igrowup from WHO, which might be easier option to use, but I personally do not know how to use them...if you also know how to use them, please let me know.

Thank you so much,
H

Martha

Research scientist

Frequent user

3 Aug 2017, 07:05

Hi ,
If using Stata for analysis i would suggest downloading the stata macros and running your dataset through to generate all Z scores based on 2006 WHO growth references.

http://www.who.int/childgrowth/software/en/

There are options for all statistical softwares (SPSS, R, SAS and stata) plus the read me document which has the instructions.

Martha

Muhammad Asim

University of Sargodha, Sargodha

Normal user

4 Aug 2017, 08:54

Valued Scholars,
I am conducting my PhD research on "Mother-Child Malnutrition:Causes and Health Consequences in Punjab, Pakistan. I have entered the data in SPSS shett. I am confused here, how I will be analyzed my dependent variable i.e. Stunting, wasting and underweight among children and in women through BMI. I want to apply Z score method designed by WHO for assassing the child malnutrition.
I have entered the data of child age, sex. weight in Kg, height in cm and for mothers age, height in cm and weight in Kg.
Now Please suggest the method in SPSS for calculating Z score method of WHO or any other software or method.
Thank you very much for support.

Bradley A. Woodruff

Self-employed

Technical expert

5 Aug 2017, 16:49

Dear Muhammed Asim:
WHO has released programming for SPSS, SAS, Stata, and R which calculates z-scores for weight-for-height, height-for-age, weight-for-age, MUAC-for-age, BMI-for-age, triceps skinfold thickness-for-age, and sub-scapular skinfold thickness-for-age. (See: http://www.who.int/childgrowth/software/en/.) However, I find the SPSS programming quit difficult to use. As an alternative, I often copy and past the necessary data from SPSS to ENA which then calculates the indices automatically. I can then copy and paste these values back into SPSS. I have compared z-scores obtained by this method and those obtained from the SPSS programming, and they are almost identical; a small proportion of subjects have z-scores which differ by only 0.01 standard deviations. But you must be careful to ensure that the data in SPSS and ENA are sorted in exactly the same way or you will end up applying the z-scores calculated in ENA to the wrong subjects in SPSS.

Jay Berkley

Frequent user

7 Aug 2017, 15:12

From the zanthro help file, it does do WHO standards and several other references. The right one needs to be selected as an option:

"The function zanthro() allows transformation of child anthropometric data to z scores using the LMS method and the reference data available from the 2000 CDC Growth Reference, the British 1990 Growth Reference, the WHO Child Growth Standards, the WHO Reference 2007, the UK-WHO Preterm Growth Reference, and the UK-WHO Term Growth Reference.... The function zanthro() allows transformation of child nthropometric data to z scores using the LMS method and the reference data available from the 2000 CDC Growth Reference, the British 1990 Growth Reference, the WHO Child Growth Standards, the WHO Reference 2007, the UK-WHO Preterm Growth Reference, and the UK-WHO Term Growth Reference."

I find zscore06 easier to use than either the WHO macro or zanthro for 0-59 month olds.

Carlos Grijalva-Eternod

UCL Institute for Global Health

Normal user

9 Aug 2017, 08:44

Hi,

There are differences between z-scores calculated using zanthro and zscore06 Stata commands.

I have estimated some examples by hand using excel and zanthro seems to produce accurate results whilst zscore06 does not. Follow this link link to see an excel sheet with examples for WAZ values.

I am not sure how much difference you will see in prevalence estimates or other measures when comparing z-scores derived using the two commands, but I would strongly recommend the use of zanthro rather than zscore06.

Regarding WHO macros in Stata, I purposely avoid using them as they are frustratingly complex to use as syntax, when compare with the alternatives. My understanding is that the macros for Stata were adapted from SAS macros, which might explain the complicated syntax

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