Adults and adolescents: assessment of nutritional status in emergency-affected populations
In July last year the ACC/Sub-committee on nutrition published two reports on the assessment of nutritional status in emergencies. One report deals with adults and the other with adolescents3.
This report describes simple techniques suitable for the assessment of the nutritional status of adults aged 20-60 years in emergency-affected populations. The report makes preliminary recommendations stressing that there is no consensus on a definitive method to assess adult undernutrition and that more research is required.
Surveys and population level assessments of chronic undernutrition
The BMI may be used to estimate the prevalence of chronic undernutrition in a population survey using the classification system below
|Classification of chronic underweight categories (Kg/m2)
In order to account for changes in body shape the Cormic Index (sitting height/standing height) must be taken into account and standardised for, when comparing the BMI of different populations.
MUAC may also be used to assess the prevalence of chronic undernutrition at the population level
Screening severely undernourished adults
BMI is inappropriate for this purpose as it is affected by oedema and body shape and difficult to measure in any particular situation. MUAC in combination with clinical signs should therefore be used to screen adult entrance into feeding centres using the following classifications.
For admission to therapeutic feeding centres
- MUAC < 160 mm irrespective of clinical signs
- MUAC 161-185 mm plus one of the following: . bilateral pitting oedema . inability to stand . apparent dehydration
- Famine oedema ( i.e. oedema demonstrable up to the knee) alone as assessed by a clinician to exclude other causes.
Additional social factors can be included in the model. The relative weighting of these must be determined locally; for example whether you need one, two or three additional social factors to tip the balance in favour of therapeutic rather than supplementary care.
For admission to supplementary feeding centres
MUAC 161-185 mm and no relevant clinical signs or few relevant social criteria
These suggested standards should only be used as a starting point and adapted according to the situation specific context.
The current WHO recommendations to compare the BMI of individual adolescents with a reference population made up of adolescents in the US using the 5th centile of this reference as a cut off point to define undernutrition may not be appropriate. Surveys using these recommendations have found unrealistically high levels of adolescent undernutrition.
There are several difficulties with anthropometry in adolescents; for example:
- body proportions, including indices using weight and height measurements change with age, making it necessary to compare an individual to adolescents in a reference population who are of the same age. As a result, age must be collected on persons screened for admission to feeding programmes or measured as survey subjects. Adolescents in many emergency affected populations do not accurately know their ages
- body proportions change with sexual development. The age at which sexual development occurs differs in different populations and complicates the comparison of subjects from one population to adolescents in a reference population
These problems affect all anthropometric indices. The following adjustments may allow better estimates:
- better methods of assessing the age of attainment of key pubertal landmarks may allow adjustment for difference in maturation age between survey and reference populations.
- Cormic Index may to some extent be used to adjust for ethnic differences in body proportions - however this technique has not been studied in adolescents.
- a new international reference consisting of adolescents from 6 countries and a new method of determining cut-off points may alleviate some of the biases from using a reference population for a single country.
- Until better methods can be developed and validated, screening for severe undernutrition in order to determine the need for therapeutic feeding should use clinical criteria.
- In surveys, some correction for different ages of sexual maturation should be carried out if the age of sexual maturation differs substantially between the survey and reference population.
For pre-pubertal adolescents, weight for height could be used as the anthropometric index and compared to revised weight for height tables currently in use.
For post-pubertal adolescents, BMI could be used as the anthropometric index and compared to a new international reference population. Appropriate cut-off points could be used to identify malnourished individuals.
- Regardless of which index is used, cut-off points are age-specific; as a result age should be collected as accurately as possible on all adolescents measured during screening or survey activities.
- The reference population of American adolescents, currently recommended by WHO for use with BMI should not be used.
- Adolescents should not undergo nutritional assessment in isolation. A large discrepancy between the estimated level of undernutrition in adolescents and other population subgroups should stimulate investigation of the validity of the methods and results of the adolescent assessment.
- In order to assess the methods and comparability of surveys, all survey reports should describe in detail the anthropometric index used, how measurements were taken, which reference population was used, how individuals were compared to this reference, and the cut-off points used to define various degrees of undernutrition.
1Adults: Assessment of nutritional status in emergencyaffected populations; July 2000 Collins.S, Duffield.A and Myatt.M
2Adolescents:Assessment of Nutritional Status in Emergency-Affected Populations, July 2000: Bradley. A, Woodruff, and Duffield. A
3Reports available from ACC/Sub-Committee on Nutrition, 20, Avenue Appia, 1211 Geneva 27, Switzerland. Email: email@example.com or online at http://acc.unsystem.org/scn/Publications/RNIS/
Taken from Field Exchange Issue 12, April 2001