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Calculation of MAM children from 6-23 months age group

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Muhammad Khan

District Nutrition Coordinator-Merlin

Normal user

3 May 2015, 19:13

Dears

We are implementing four year CMAM program and through this program we cover 6-23 months age MAM children in SFP. At the start of the year-3 in program, we reached more than 100% children in SFP.
Overall GAM percent for under two years in program is more than 80% (>80% identified GAM cases are in 6-23 months age Group). This trend is similar in two other districts of SINDH Pakistan.
Please can you suggest technically how to calculate GAM beneficiaries for the 6-23 months age group? Is their any study, experience or guideline available on situation?

Thanks in advance for your response...

Mark Myatt

Consultant Epideomiologist

Frequent user

4 May 2015, 07:58

I think you are confused.

You cannot have a coverage of more than 100%. This sort of figure is usually quoted when coverage is estimated using (highly inaccurate) indirect methods which confuse prevalence for incidence.

The fact that > 80% of GAM cases are aged between 6 and 23 months does not mean that the prevalence of GAM in this in this age-group is 80%. You need to have the prevalence. SMART type surveys usually provide age-specific prevalence estimates for this age-group.

Anyway ... The standard approach to your problem is to apply the formula:

  case load = N * P * K * C

where:

N is the size of the population in the program area. An appropriate value for N is usually derived from census data.

P is estimated prevalence. This is usually estimated using a nutritional anthropometry survey (e.g. a SMART survey). It is important that prevalence is estimated for the program's admitting case-definition.

K is a correction factor to account for new (incident cases) over a given time period. This is usually taken to be 2.6 over one year.

C is the expected mean program coverage over a given time period. You have an indirect estimate but this is a clear overestimate. You could correct what you have by divining by K (above). If you have an indirect estimate of coverage of 120% then you might use:

  C = 120 / 2.6 = 46% = 0.46 (as a proportion)

If we assume:
         Population (N) = 10,501
         Prevalence (P) = 8.7% = 0.087 (as a proportion)
         Correction (K) = 2.6
  Expected coverage (C) = 46% = 0.46 (as a proportion)

We get a one-year case-load of:
  case load = N * P * K * C
  case load = 10501 * 0.087 * 2.6 * 0.46
  case-load = 1093

You can use the 95% CI on P to get a nominal 95% CI on the case-load.

I hope this is of some use.

The material presented in response is based on:

Garenne M, Willie D, Maire B, Fontaine O, Eeckels R, Briend A, Van den Broeck J, Incidence and duration of severe wasting in two African populations, Public Health Nutr. 2009 Nov;12(11):1974-82

Anon, WHO, UNICEF, WFP and UNHCR Consultation on the Programmatic Aspects of the Management of Moderate Acute Malnutrition in Children under five years of age 24-26 February 2010, WHO, Geneva, 2010

MacMahon B, Pugh TF, Epidemiology Principles and Methods, Little Brown & Company, Boston, USA, 1970

Miettinen O, Estimability and estimation in case-referent studies, American Journal of Epidemiology, 1976;103(2):226–235

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