Module 7: Measuring Malnutrition

“We pledge our political will and our common and national commitment to achieving food security for all and to an ongoing effort to eradicate hunger in all countries, with an immediate view to reducing the number of undernourished people to half their present level no later than 2015.”(1)

This was the pledge made by all signatories of the Rome Declaration on World Food Security at the World Food Summit in 1996. An international commitment to improving global nutrition and food security was born, and targets for reducing child and maternal malnutrition were set. However, it became evident that monitoring the prevalence and trends of malnutrition among countries was going to be crucial for evaluating the progress towards achieving these goals.

Quantifying regional nutrition status is important for identifying the burden caused by undernutrition and initiating intervention among countries. Nutrition research has many applications. Quality nutrition research can:

Nutrition research can be disseminated to policymakers and key stakeholders (including international donors, academia, and NGOs) in order to advocate for nutrition interventions and policy change.

There is a multitude of research areas in the complex social, political, economic, and behavioral aspects of nutrition and food security. Frequently, the main goals of nutrition research are to quantify and assess the state of undernutrition in a population. This begins with collecting data. Data collection methodologies may use approaches that are quantitative, qualitative, based on survey results or anthropometric indicators, or a mix of all. Indicators of nutrition status can be categorized into biological indicators and social determinants. We review some common indicators used to assess the state of undernutrition and its underlying causes.

Biological Nutrition Indicators

One way to measure malnutrition is to study nutrition-related outcomes, such as growth restriction, weight loss, and the occurrence of deficiency-related disorders. Common indicators recommended by the WHO include anthropometric measurements, biochemical indicators, and clinical signs of malnutrition.(2) Anthropometric indicators are more “sensitive over the full spectrum of malnutrition” than other indicators, though they lack specificity from changes in body measurements that may be the result of other biological or environmental factors.(3) Biochemical and clinical analysis may be less practical “because of the logistical difficulties and because data collection…is expensive and time-consuming.”(4) For all indicators, it is important to standardize measurements and ensure equipment is properly calibrated in order to reduce the margin of error.

Anthropometric Indicators

Anthropometry refers to body measurements. The basic measurements taken from children include age, sex, weight, length, and height, which are then  compared to the sex-specific National Centre for Health Statistics (NCHS) and WHO-guided international reference population as a way to assess the level of undernutrition. Evidence has shown that growth patterns of well-fed, healthy children are the same for all races and ethnicities, so this reference population is used for all areas of the world.(5) 

Common anthropometric indicators combine measurements with age. In particular, stunting represents low height-for-age, wasting represents low weight-for-height, and underweight scores represent low weight-for-age. Stunting provides an indicator of chronic undernutrition since it quantifies growth potential restricted; wasting is an indicator of acute undernutrition since it quantifies weight loss; the degree of underweight is an indicator of both wasting and stunting, combining measures of “the current status of body proportion and linear growth.”(6)(7) 

As a “predictor of newborn health and survival,” low birth weight (LBW) is defined by the WHO as the weight of a baby being less than 2.5 kilograms at birth.(8) Low birth weight is an indicator of the nutritional status of both mother and infant, and mothers with low pre-pregnancy weight have an increased risk of having a LBW baby.(9) A LBW baby, in addition to being at increased risk of mortality, has a higher risk of becoming a stunted child, who, without proper food and care, will grow to become a stunted adult. Stunted women then “[perpetuate] the cycle of malnutrition from generation to generation” with pregnancy.(10) 

A common anthropometric indicator to measure adult malnutrition is body mass index (BMI) (excluding pregnant women and adults with edema). BMI is calculated by dividing a person’s weight in kilograms by their height in meters squared. (11) This value is compared to reference values that can gauge whether a person is healthy or malnourished. A person is deemed undernourished if they have a BMI under 18.5, and is severely undernourished with a BMI under 16.(12)

Previous anthropometric indices of malnutrition have used the mid-upper arm circumference (MUAC). While the advantage of the MUAC has been the simplicity of using only a tape to measure one quantitative dimension, MUAC is difficult to administer accurately and consistently. The tautness with which the tape is pulled can greatly affect the variation in recorded measurements. MUAC also only provides an estimate of acute, not chronic, malnutrition, and is thus limited in utility.(13)

Biochemical Indicators

Micronutrient deficiencies are not easily diagnosable unless they are severe enough to result in visible disorders or illnesses. When disorders are not apparent, diagnostics can be used to test bodily samples (i.e. blood or urine) in order to measure an individual’s micronutrient status. For example, iron deficiency anemia can be diagnosed by measuring the level of hemoglobin in the blood. Low levels of hemoglobin, as compared with age and sex-specific reference values, indicate anemia. In the field, a reliable device that has been implemented to test hemoglobin levels has been a microphotometer, such as the portable HemoCue. Other indicators, such as the WHO’s hemoglobin color scale or the Sahli method, have not proven as effective, being “both highly subjective and therefore less accurate than the more objective HemoCue method.”(14) 

Clinical Indicators

Clinical manifestations of micronutrient deficiencies can be used to identify certain cases of malnutrition. For example, iodine deficiency can be diagnosed based on the presence of a goiter, which is a large protrusion in the neck caused by the swelling of the thyroid gland. Vitamin A deficiency in children can be diagnosed based on the symptoms of night blindness and Bitot’s spots, small spots on the white areas of the eye. The WHO has developed a way to classify night blindness based on four questions:(15)

The clinical manifestations of nutrition deficiencies may only appear in severe cases. Depending on the type of deficiency and the health consequences related to its condition, even clinical indicators may not provide the most well-defined representation of deficiency. For instance, it is important to consider the possibility of confounding factors when conducting nutrition evaluations. One such clinical indicator that actually serves as a confounding factor to true anthropometric measurements is the condition of edema, water retention and extreme swelling that can be diagnosed by pressing on the skin. It is important to note that underweight and wasting cannot be used to measure malnutrition for children with edema. Water retention increases body weight, affecting measurements of weight-for-height and weight-for-age. It has been determined that children who present with edema in both feet should be classified as undernourished, regardless of their wasting and underweight status.(16)

Using clinical indicators requires close inspection. It is necessary to consider the various causes and consequences of deficiency – how nutrition can manifest itself such that any imbalance is visible to or hidden from the eye. When evaluating populational micronutrient deficiency, assessments may also exclude individuals who are moderately malnourished but do not yet express clinical signs. To use clinical indicators appropriately, experts must make a detailed evaluation of the clinical history and status of each individual.

Social Determinants of Undernutrition

Nutrition research can be aimed at identifying the various social, cultural, political, and economic factors of nutrition in order to fully understand the underlying causes of malnutrition. The social determinants of undernutrition can be explored through both qualitative and quantitative research methods. Qualitative methods help develop a more in-depth understanding of social factors of nutrition, but are often time-consuming and impractical for large-scale surveillance. Nevertheless, exploring the issues of food security, dietary diversity, and infant-feeding practices can provide a comprehensive understanding of a population’s nutritional status. 

Food Security

Indicators of household food insecurity measure physical availability of food, proportion of food budget spent on staple food items, dietary diversity, and financial ability to acquire a variety of non-staple food items. Research questions should be designed to identify vulnerable groups, such as the person in the household who is most likely to eat the least when food is scarce. 

Indicators of food insecurity may include:(17)

Since food security often depends on the financial ability of a household to purchase quality food items, it is beneficial to collect information about socioeconomic status and income-earning potential. 

Indicators of household socioeconomic status may include:(18)

Qualitative research methods may be used to identify context-specific aspects of food security in a particular area. For example, in rural Burkina Faso, where people’s livelihoods depend largely upon agriculture, food security has a strong seasonal pattern. During the harvest period of October to April there is ample food available, but from June to September there is less agricultural production and food insecurity becomes more of a threat.(19) The seasonal pattern of food security is an important aspect for rural villages in many developing countries. People living with low socioeconomic status who are not financially stable are most affected by seasonality and its effects on food prices. Therefore, in order to capture the seasonal contrast and attain accurate measurements, it is important to collect data on food security at least twice a year. When conducting research, it is imperative to consider the context in which the study is conducted; with nutrition, harvest seasons are ingrained in this context.  

In the United States, the USDA’s Household Food Security Survey Module has been developed as a qualitative tool for assessing food insecurity and hunger. Some questions ask participants to describe their experiences with food insecurity, perceptions about food insecurity, consequences of low food intake, and other behaviors related to food insecurity.(20) Previous evaluation of the survey method found that food insecurity scores were negatively and significantly correlated with income and food expenditure. The design of the survey has been extensively tested for accuracy and has proven robust.(21) 

In order to address the challenge of measuring food insecurity in developing countries, the USAID’s Food and Nutrition Technical Assistance Project (FANTA) has developed the Household Food Insecurity Access Scale (HFIAS), an adaptation of the survey applied in the United States. The HFIAS includes a set of questions that address anxiety about household food supply, insufficient food quality, insufficient food intake, and the consequences of an inadequate diet. FANTA has published a guide to implementing the HFIAS, giving an overview of the questionnaire, reviewing interview skills related to methods of asking questions and recording responses, and suggesting appropriate adaptations. The guide is meant to serve as a tool for designing food security measurement surveys (the full document can be viewed at http://www.fantaproject.org/publications/hfias_intro.shtml). The HFIAS has been used in many developing countries. For example, in Burkina Faso, the HFIAS, in conjunction with a dietary diversity score, has proven to be a reliable indicator of household food security.(22) 

Dietary Diversity

Investigating dietary diversity helps identify the dietary composition of individuals and households. Individual food intake surveys can provide information about types of food that are regularly purchased and consumed, which can thus determine the variety of non-staple food items available. However, simple inquiry about ‘what people eat on a regular basis’ is subject to reporting error  due to poor recollection over long periods of time. As a result, food intake surveys should ask participants to focus on a specific, shortened timeframe (i.e. up to 24 hours prior to the interview). A checklist that incorporates a variety of food items can also be helpful for information recall, as participants can simply mark which fruits and vegetables, dairy products, meat, fish, or breads and grains were consumed. 

Considerations of dietary diversity include:(23)

Breastfeeding and Complementary Feeding Practices

Infant feeding practices within a household can be assessed by collecting information from the mother, based on her youngest child. Information should include age of the child, birth weight, current weight, and health status (i.e. ailments, morbidity, and disease). Research questions should target whether the child is breastfed exclusively for six months, how and when the child transition to complementary food, and an explanation of common, suboptimal breastfeeding practices in a particular location. 

Example questions about infant feeding practices:(24)

For children over six months:

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Footnotes

(1) FAO (1996). Rome Declaration on World Food Security. Proceedings of the World Food Summit; November 13-17 1996; Rome, Italy. Accessed 8 November 2011.

(2) WHO (2005). Malnutrition: quantifying the health impact at national and local levels. Accessed 31 October 2011.

(3) Ibid.

(4) Setboonsarng, S. (2005). Child Malnutrition as a Poverty Indicator: An evaluation in the context of different development interventions in Indonesia. ADB Institute Discussion Paper No. 21. Accessed 31 October 2011.

(5) Centers for Disease Control and Prevention. (2005). A Manual: Measuring and Interpreting Malnutrition and Mortality. Accessed 31 October 2011.

(6) Marriott, B.P., White, A.J., Hadden, L., Davies, J.C., & Wallingford, J.C. (2009). How well are infant and young child WHO feeding indicators associated with growth outcomes? An example from Cambodia. Maternal and Child Nutrition, 6: 358-737. 

(7) WHO (2005). Malnutrition: quantifying the health impact at national and local levels. Accessed 31 October 2011.

(8) WHO (2008). WHO Statistical Information System – Indicator definitions and metadata, 2008. Accessed 31 October 2011.

(9) Nahar, S., Mascie-Taylor, C.G.N., & Begum, H.A. (2007). Maternal anthropometry as a predictor of birth weight. Public Health Nutrition, 10(7): 965-970.  

(10) Centers for Disease Control and Prevention. (2005). A Manual: Measuring and Interpreting Malnutrition and Mortality. Accessed 31 October 2011.

(11) WHO (2005). Malnutrition: quantifying the health impact at national and local levels. Accessed 31 October 2011.

(12) Centers for Disease Control and Prevention. (2005). A Manual: Measuring and Interpreting Malnutrition and Mortality. Accessed 31 October 2011.

(13) Ibid.

(14) Ibid.

(15) Ibid.

(16) Ibid.

(17) Food Security and Nutrition Surveillance Project. (2010). Questionnaire for Round Data Collection. .

(18) Ibid.

(19) Frongillo, E.A. & Nanama, S. (2006). Development and validation of an experience-based measure of household food insecurity within and across seasons in northern Burkina Faso. American Society for Nutrition, 136: 1409S – 1419S

(20) USAID (2007). Household Food Insecurity Access Scale for Measurement of Food Access: Indicator Guide. Accessed 31 October 2011.

(21) FAO (2003). Measurement and assessment of food deprivation and undernutrition. Proceedings of the International Scientific Symposium; June 26-28 2002; Rome, Italy. Accessed 31 October 2011.

(22) Becquey, E., Martin-Prevel, Y., Traissac, P., Dembele, B., Bambara, A., & Delpeuch, F. (2010). The household food insecurity access scale and an index-member dietary diversity score contribute valid and complementary information on household food insecurity in an urban West-African setting. The Journal of Nutrition, 140(12): 2233-2240.

(23) Food Security and Nutrition Surveillance Project. (2010). Questionnaire for Round Data Collection. 

(24) Ibid.