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Nutrition Section, Programme Division, UNICEF, New York, NY 10017
2To whom correspondence should be addressed. E-mail: wschultink{at}unicef.org.
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ABSTRACT |
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 TOP ABSTRACT VITAMIN A SUPPLEMENTATIONU5MR AS AN INDICATORLITERATURE CITED |
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KEY WORDS: • vitamin A deficiency • child mortality • vitamin A indicator
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VITAMIN A SUPPLEMENTATION |
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TOPABSTRACTVITAMIN A SUPPLEMENTATIONU5MR AS AN INDICATORLITERATURE CITED |
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,2
). Currently, vitamin A supplementation is the major program approach to reducing VAD. It has proven to be doable and cost-effective, and it has no adverse effects. Indicators for use of vitamin A supplementation programs
Indicators are important for deciding whether a program needs to be initiated, continued, changed or stopped. Vitamin A status of a population can be assessed in different ways (3
). Population surveys can be undertaken for measuring serum retinol concentration to determine the percentage of the population with values below a certain cutoff point (4
). Furthermore, the prevalence of clinical signs of deficiency such as xerophthalmia can be measured (5
,6
). Each of these indicators has its own strengths and weaknesses.
In certain instances, no information about any of the above indicators is available, or the available information is outdated. To collect this information takes time and money. To speed up the decision-making process, and possibly facilitate discussion with policy makers, it may be possible to use a surrogate indicator that would suggest whether a problem is likely and full-scale assessment is necessary.
A good surrogate indicator must have a close association with the vitamin A status of the population (in the nonintervention state), and it should be readily available for all populations/countries at risk so that no time or additional funds are needed to collect information. The Vitamin A Global Initiative report suggests that the under-five mortality rate (U5MR), a rate widely available for most countries, might serve that purpose. The report tentatively suggested that a U5MR >70 indicates that VAD of public health importance is likely (7
). The following points are addressed: does it make sense to use the U5MR as a surrogate indicator, and, if so, is 70 the appropriate cutoff?
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U5MR AS AN INDICATOR |
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TOPABSTRACTVITAMIN A SUPPLEMENTATIONU5MR AS AN INDICATORLITERATURE CITED |
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). Therefore, mortality rates cannot be used to make any judgments on a year-to-year basis. Furthermore, it is clear that mortality rates are influenced by many factors and not just the vitamin A status of the population. Figure 1
shows the distribution of the U5MR for countries where the United Nations Children’s Fund (UNICEF) supports programs. The distribution shows a wide variation, ranging from <10 to >220. Figure 2
shows the U5MR distribution from countries for which vitamin A survey data are available [unpublished data from the World Health Organization (WHO)]. Not all these surveys were representative of the whole population, and they were conducted with different methodologies and sampling methods. Most of the countries did have a VAD problem, as indicated by the survey. Countries in which surveys did not suggest a VAD problem had a U5MR ranging from <10 to a maximum of 40. Nonetheless, 19 of 41 countries with mortality rates of <40 still had a VAD problem. All countries with a mortality rate >40 had a VAD problem. It is clear that a U5MR of >40 indicates that a problem probably exists; however, a problem may exist even if the U5MR is <40.
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presents information about mortality rates of countries classified per region as defined by UNICEF (8
). For each region the following information is presented (numbers in brackets): the number of countries, the number of countries with a mortality rate above 70, the number of countries with a rate above 50, the number of countries with and without a VAD problem and the number of countries where a large-scale vitamin A capsule program is ongoing. Changing the cutoff from 70 to 50 would indicate that the number of countries with possible VAD problems in Sub-Saharan Africa, the Middle East and North Africa, East Asia and the Pacific, Latin America and the Caribbean, and Central and Eastern Europe and the Commonwealth of Independent States would increase by nine countries. Furthermore, it is clear from Table 1
that in the Middle East and North Africa, East Asia and the Pacific and Latin America and the Caribbean the number of countries with an ongoing vitamin A program is larger than the number of countries with a mortality rate above 50. Using the mortality rate above 50 as the indicator, more countries would need to start a vitamin A program in Sub-Saharan Africa, South Asia, and Central and Eastern Europe and the Commonwealth of Independent States. Included in this group are countries such as South Africa, Botswana, Zimbabwe, Kyrgyzstan and Uzbekistan.
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shows sensitivity and specificity calculations by using the U5MR of 70 and 50 as cutoff points compared with the presence of VAD as proven by a survey (based on unpublished WHO data as shown in Fig. 2
). Too little survey data were available for Central and Eastern Europe and the Commonwealth of Independent States; therefore, this region was excluded from the table. For the 40 countries with survey data in Sub-Saharan Africa, for example, changing the mortality rate cutoff from 70 to 50 would increase the sensitivity from 0.93 to 1.0. In other words, in Sub-Saharan Africa, every country with a mortality rate higher than 50 has a VAD problem, whereas two countries have a VAD problem but they have a mortality rate lower than 70 and higher than 50. Changing the mortality cutoff from 70 to 50 improves the sensitivity for every region except South Asia. It should also be noted that the sensitivity in the Middle East and North Africa as well as in Latin America is low because a number of countries with mortality rates lower than 50 still have a VAD problem, as indicated by survey data. The sensitivity in Sub-Saharan Africa, South Asia and to a lesser extent in East Asia and the Pacific is quite good.
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The need for initiation and/or continuation of vitamin A supplementation programs is greatest in Sub-Saharan Africa and South and East Asia. The U5MR relates well to VAD in these parts of the world, and it can be an easy and powerful way to advocate for the need of vitamin A programs. A cutoff of 50 would include all deficient countries. It is proposed that when a country has a U5MR >50, this is a sign that VAD is very likely to be a public health problem that requires immediate or continuing action. These actions include proper, formal assessment of the vitamin A status of the population and, when not ongoing, initiation of vitamin A capsule distribution and other programmatic action initiatives. Countries with a U5MR between 20 and 50 should assume they have a VAD public health problem until surveys prove otherwise.
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FOOTNOTES |
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3 Abbreviations used: CEE, Central and Eastern Europe; CIS, Commonwealth of Independent States; U5MR, under-five mortality rate; UNICEF, United Nations Children’s Fund; VAD, vitamin A deficiency; WHO, World Health Organization.
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LITERATURE CITED |
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TOPABSTRACTVITAMIN A SUPPLEMENTATIONU5MR AS AN INDICATORLITERATURE CITED |
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1. Beaton, G. H., Martorell, R., Aronson, K. J., Edmonston, B., McCabe, G., Ross, A.C. & Harvey, B. (1993) Effectiveness of vitamin A supplementation in the control of young child morbidity and mortality in developing countries. ACC/SCN State of the Art Series: Nutrition Policy Discussion Paper 1993 United Nations, New York, NY. .
2. Fawzi, W. W., Thomas, C. C., Herrera, G. M. & Mosteller, F. (1993) Vitamin A supplementation and child mortality. A meta-analysis. J. Am. Med. Assoc. 269:898-903.
3. WHO (1996) Indicators for assessing vitamin A deficiency and their application in monitoring and evaluating intervention programs 1996 WHO Geneva, Switzerland. .
4. de Pee, S. & Dary, O. (2002) Biochemical indicators of vitamin A deficiency: serum retinol and serum retinol binding protein. J. Nutr. 132:2895S-2901S.
5. Sommer, A. & Davidson, F. R. (2002) Assessment and control of vitamin A deficiency: the Annecy accords. J. Nutr. 132:2845S-2850S.
6. Christian, P. (2002) Recommendations for indicators: night blindness during pregnancy —a simple tool to assess vitamin A deficiency in a population. J. Nutr. 132:2884S-2888S.
7. Vitamin A Global Initiative (1998) A strategy for acceleration of progress in combating vitamin A deficiency: consensus of an informal technical consultation 1998 UNICEF New York, NY. 18–19 December 1997.
8. UNICEF (2001) The State of the World’s Children 2001 2001 UNICEF New York, NY. .
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