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The Institute of Nutrition, Mahidol University, Salaya, Phutthamonthon, Nakhon Pathom 73170, Thailand
2To whom correspondence should be addressed. E-mail: numdk{at}mahidol.ac.th.
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONCLINICAL INDICATORSFUNCTIONAL INDICATORSBIOCHEMICAL INDICATORSLITERATURE CITED |
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KEY WORDS: • xerophthalmia • maternal night blindness • pupillary dark adaptation • serum retinol • breast milk retinol
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONCLINICAL INDICATORSFUNCTIONAL INDICATORSBIOCHEMICAL INDICATORSLITERATURE CITED |
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). Among children under 5 years of age, around 3 million have ocular signs of VAD, and 140 million have inadequate vitamin A status and are at increased risk of morbidity and mortality. In recent years, many countries have executed intervention programs to control and prevent VAD. Major interventions include periodic, high dose vitamin A supplementation, food fortification and dietary modification. One of the characteristics of successful community programs was identified as "monitoring, evaluation and management information systems" (2
). Monitoring activity is essential to adjust the direction of the program and frequently involves process indicators. In addition, evaluation of program effectiveness measures the impact on vitamin A status as represented by biological indicators. This article provides recommendations for outcome indicators useful for monitoring and evaluating vitamin A programs. These recommendations are based on the suggestions provided at the International Vitamin A Consultative Group Meeting (IVACG) workshop held 30 October to 2 November 2000 in Annecy, France, and at the pre-XX IVACG meeting on 11 February 2001, in Hanoi, Vietnam.
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CLINICAL INDICATORS |
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TOPABSTRACTINTRODUCTIONCLINICAL INDICATORSFUNCTIONAL INDICATORSBIOCHEMICAL INDICATORSLITERATURE CITED |
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,4
). These eye signs have been widely accepted as clinical criteria to establish the existence of a public health problem among preschool-age children (3
,5
) as well as to initiate vitamin A supplementation programs. In such settings, the effectiveness of the program should be demonstrated by a reduction in the prevalence of xerophthalmia, especially new, incident cases. Impact evaluation of vitamin A capsule distribution programs in Indonesia (6
) and Nepal (7
) showed a reduction in the incidence of new cases of XN and X1B after 1 year. XN tends to be unnoticed in children <2 years of age (8
), and X1B tend to persist, even after improvement in vitamin A status (6
). A reduction in the incidence of new cases is therefore a more meaningful indicator than a lack of change in prevalence, much of which often represents older, established, nonresponsive cases.
Evidence in several countries, particularly in southern Asia (9
,10
), indicates that XN is common among pregnant women, especially in their third trimester, with prevalence rates around 10%. In Nepal, night-blind pregnant women tended to be more vitamin A deficient (11
) and showed an increased risk of mortality from infection (12
). XN during pregnancy (within the past 3 y) also correlates well with other indicators of vitamin A inadequacy in the community such as xerophthalmia, serum retinol, breast milk vitamin A, impression cytology and dark adaptation (11
). Vitamin A supplementation of pregnant women in Nepal significantly reduced XN by 67% (13
). Existing data suggest that a prevalence of maternal XN of >5% can be used to identify a public health problem of VAD in a population (14
). Therefore, in areas where XN occurs, maternal XN is recommended as an outcome indicator to evaluate the impact of intervention programs that target pregnant women or the whole community; they will not respond to interventions that reach only young children.
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FUNCTIONAL INDICATORS |
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TOPABSTRACTINTRODUCTIONCLINICAL INDICATORSFUNCTIONAL INDICATORSBIOCHEMICAL INDICATORSLITERATURE CITED |
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). Abnormal pupillary thresholds correlated strongly in a relative dose-response relationship (15
) with serum retinol concentrations (15
–17
). Vitamin A supplementation improved pupillary scores significantly among young children in Indonesia (15
) and India (16
) as well as in pregnant women in Nepal (17
). Based on existing data, vitamin A programs should be initiated when the average pupillary dark adaptation score of the population is worse than -1.11 log cd/m2. The target populations should include children aged 2–6 years and pregnant women during the second or third trimester. To claim success, a vitamin A program should at least improve pupillary dark adaptation threshold to scores better than -1.24 log cd/m2 (18
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BIOCHEMICAL INDICATORS |
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TOPABSTRACTINTRODUCTIONCLINICAL INDICATORSFUNCTIONAL INDICATORSBIOCHEMICAL INDICATORSLITERATURE CITED |
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). It is reliable at assessing the status of a population, and it is effective in detecting a change in population status over time. A cutoff of >15% of a preschool population with serum retinol below 0.70 µmol is recommended as indicative of VAD (19
) and thus can be used as an indicator of the achievement of an intervention program. Even more sensitive and reliable is the progress in shifting serum retinol distributions. In Guatemala (20
), sugar fortification with vitamin A resulted in a shift of serum retinol distribution toward normal (Fig. 1
). After the program was suspended, the prevalence of low serum retinol increased to 26%; 6 months after fortification was renewed, the prevalence dropped to 10% (21
) and remained at 16% in 1995 (22
). Likewise, in Honduras, fortification of sugar with vitamin A resulted in a marked reduction in the number of children with low serum retinol, from 40% in 1967 (23
) to 13% in 1996 (24
). A similar pattern of improvement was observed in the response to margarine fortification in the Philippines (25
). For more details on food fortification, consult the article by Dary and Arroyave in this volume.
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,26
). Casual milk sampling concentrations of retinol, although listed as a potential criterion at an informal WHO workshop (5
), is generally more difficult to analyze and is considered less reliable except under ideal laboratory conditions. Recent data from a vitamin A supplementation trial in lactating Bangladeshi women indicated that the most responsive indicator was the measurement of breast milk vitamin A per gram of fat in casual milk samples (27
). Breast milk vitamin A was used as one of the evaluation indicators of sugar fortification in Guatemala (20
). The median value of breast milk vitamin A increased from 0.88 µmol at baseline to a peak of 1.40 µmol. Distribution of vitamin A concentrations in milk shifted significantly toward higher values during the program period. The percentage of mothers with a concentration in milk below 0.70 µmol fell from 38% at baseline to 10% after 18 mo of a sugar fortification program. Breast milk vitamin A was also used to evaluate the effect of fortification of monosodium glutamate with vitamin A in Indonesia (28
). A significant increase in the average milk vitamin A concentration was observed in the program areas, whereas no change was reported in the control areas. Similar results were found elsewhere (29
). Indicators are discussed in another chapter. Breast milk was not considered to be as simple and reliable an indicator as serum retinol, although in careful hands it does show a response. In summary, the outcome indicators are important in evaluating vitamin A intervention programs. Such indicators include the following:
Before the outcomes are measurable, program managers can track the progress of their interventions through the shift of mean or median values or the frequency distribution. Timing of program evaluation depends on the type of intervention (e.g., food-based strategies usually take longer than supplementation), the severity of VAD, the age of the target group and whether the programs are single or integrated.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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3 Abbreviations used: VAD, vitamin A deficiency; WHO, World Health Organization. X1B, Bitot’s spots; XN, night blindness.
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LITERATURE CITED |
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TOPABSTRACTINTRODUCTIONCLINICAL INDICATORSFUNCTIONAL INDICATORSBIOCHEMICAL INDICATORSLITERATURE CITED |
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1. World Health Organization (2000) Nutrition for health and development. WHO/NHD/00 6WHO, Geneva, Switzerland.
2. Underwood, B. (1998) Prevention of vitamin A deficiency. Howson, C. P. Kennedy, E. T. Horwitz, A. eds. Prevention of Micronutrient Deficiencies.Tools for Policymakers and Public Health Workers 1998:103-165 National Academy Press Washington, DC. .
3. Sommer, A. (1982) Nutritional Blindness: Xerophthalmia and Keratomalacia 1982 Oxford University Press New York, NY. .
4. Sommer, A. & West, K. P. (1996) Vitamin A Deficiency: Health, Survival and Vision 1996 Oxford University Press New York, NY. .
5. World Health Organization (1996) Indicators for assessing vitamin A deficiency and their application in monitoring and evaluating intervention programmes. WHO/NUT/96 10WHO, Geneva, Switzerland.
6. Djunaedi, E., Sommer, A., Pandji, A., Kusdiono, & Taylor, H. R., Aceh Study Group (1988) Impact of vitamin A supplementation on xerophthalmia: a randomized controlled community trial. Arch. Ophthalmol. 106:218-222.[Abstract]
7. Katz, J., West, K. P., Khatry, S. K., Thapa, M. D., LeClerq, S. C., Pradhan, E. K., Pokhrel, R. P. & Sommer, A. (1995) Impact of vitamin A supplementation on prevalence and incidence of xerophthalmia in Nepal. Invest. Ophthalmol. Vis. Sci. 36:2577-2583.
8. Underwood, B. A. & Olson, J. A. (1988) A brief guide to current methods of assessing vitamin A status. A report of the International Vitamin A Consultative Group (IVACG) 1988 The Nutrition Foundation, Inc Washington, DC. .
9. Katz, J., Khatry, S. K., West, K. P., Humphrey, J. H., LeClerq, S. C., Pradhan, E. K., Pokhrel, R. P. & Sommer, A. (1995) Night blindness is prevalent during pregnancy and lactation in rural Nepal. J. Nutr. 125:2122-2127.
10. Dixit, D. T. (1966) Night blindness in third trimester of pregnancy. Indian J. Med. Res. 54:791-795.
11. Christian, P., West, K. P., Khatry, S. K., Katz, J., Shrestha, R., Pradhan, E. K., LeClerq, S. C. & Pokhrel, R. P. (1998) Night blindness of pregnancy in rural Nepal —nutritional and health risks. Int. J. Epidemiol. 27:231-237.
12. Christian, P., West, K. P., Khatry, S. K., Kimbrough-Pradhan, E., LeClerq, S. C., Katz, J., Shrestha, S. R., Dali, S. M. & Sommer, A. (2000) Night blindness during pregnancy and subsequent mortality among women in Nepal: effects of vitamin A and ß-carotene supplementation. Am. J. Epidemiol. 152:542-547.
13. Christian, P., West, K. P., Khatry, S. K., Katz, J., LeClerq, S., Pradhan, E. K. & Shrestha, S. R. (1998) Vitamin A or beta-carotene supplementation reduces but does not eliminate maternal night blindness in Nepal. J. Nutr. 128:1458-1463.
14. 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.
15. Congdon, N., Sommer, A., Severns, M., Humphrey, J., Friedman, D., Clement, L., Wu, L. S. F. & Natadisastra, G. (1995) Pupillary and visual thresholds in young children as an index of population vitamin A status. Am. J. Clin. Nutr. 61:1076-1082.
16. Sanchez, A., Congdon, N. G., Sommer, A., Rahmathullah, L., Venkataswamy, P. G., Chandravathi, P. S. & Clement, L. (1997) Pupillary threshold as an index of population vitamin A status among children in India. Am. J. Clin. Nutr. 65:61-66.
17. Congdon, N. G., Dreyfuss, M. L., Christian, P., Navitsky, R. C., Sanchez, A. M., Wu, L. S. F., Khatry, S. K., Thapa, M. D., Humphrey, J., Hazelwood, D. & West, K. P., Jr. (2000) Responsiveness of dark adaptation threshold to vitamin A and ß-carotene supplementation in pregnant and lactating women in Nepal. Am. J. Clin. Nutr. 72:1004-1009.
18. Congdon, N. G. & West, K. P., Jr. (2002) Physiologic indicators of vitamin A status. J. Nutr. 132:2889S-2894S.
19. de Pee, S. & Dary, O. (2002) Biochemical indicators of vitamin A deficiency: serum retinol and serum retinol binding protein. J. Nutr. 132:2895S-2901S.
20. Arroyave, G., Aguilar, J. R., Flores, M. & Guzman, M. A. (1979) Evaluation of sugar fortification with vitamin A at the national level 1979:1-82 Pan American Health Organization Publication 384 PAHO, Washington, DC. .
21. Pineda, O. (1993) Fortification of sugar with vitamin A. Nutriview 2:6-7.
22. Ministerio de Salud Publica y Asistencia Social de Guatemala (1996) Encuesta Nacional de Micronutrientes 1996 Guatemala City Guatemala. .
23. Institute of Nutrition of Central America and Panama (INCAP) and the Interdepartmental Committee on Nutrition for National Development (1972) Nutritional evaluation of the population of Central America and Panama, 1965–1967 1972 DHEW Publication (HSM) 72–8120: Department of Health, Education and Welfare Washington, DC. .
24. Secretaria de Salud, Subsecretaria de Riesgos Poblacionales (1997) Encuesta nacional sobre micronutrientes, Hondura, 1996 1997 Tegucigalpa Honduras. .
25. Solon, F. S., Solon, M. S., Mehansho, H., West, K. P., Sarol, J., Perfecto, C., Nano, T., Sanchez, L., Isleta, M., Wasantwisut, E. & Sommer, A. (1996) Evaluation of the effect of vitamin A-fortified margarine on the vitamin A status of preschool Filipino children. Eur. J. Clin. Nutr. 50:720-723.[Medline]
26. Stoltzfus, R. J. & Underwood, B. A. (1995) Breast-milk vitamin A as an indicator of the vitamin A status of women and infants. WHO Bull 73:703-711.
27. Rice, A. L., Stoltzfus, R. J., de Francisco, A. & Kjolhede, C. L. (2000) Evaluation of serum retinol, the modified-relative dose-response ratio, and breast-milk vitamin A as indicators of response to postpartum maternal vitamin A supplementation. Am. J. Clin. Nutr. 71:799-806.
28. Muhilal Permaesih, D., Idjradinata, Y. R. & Muherdiyantiningsih Karyadi, D. (1988) Vitamin A-fortified monosodium glutamate and health, growth and survival of children: a controlled field trial. Am. J. Clin. Nutr. 48:1271-1276.
29. Stoltzfus, R. J., Hakimi, M., Miller, K. W., Rasmussen, K. M., Dawiesah, S., Habicht, J. P. & Dibley, M. J. (1993) High dose vitamin A supplementation of breast-feeding Indonesian mothers: effects on the vitamin A status of mother and infant. J. Nutr. 123:666-675.
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