Assessment of vitamin A status of preschool children in a sub-Saharan African setting: Comparative advantage of modified relative-dose response test

A nationally-representative sample of 2,696 preschool children living in congo was examined during august-september 2003 to determine the rates of vitamin a deficiency. ninety clusters of 30 children,aged six months to six years,were selected,using a randomized two-level cluster-sampling method. vitamin a deficiency was determined by assessing the prevalence of active xerophthalmia (nightblindness and/or bitot spots) in the cross-over sample of 2,696 individuals. a semi-quantitative seven-day dietary questionnaire was concurrently applied to the mothers of children enrolled to estimate the latter's consumption of vitamin a-rich food. vitamin a status was assessed by performing the modified relative dose-response test (mrdr) on dried blood spots (dbs) from a subsample of 207 children aged less than six years and the impression cytology with transfer (ict) test on a subsample of 1,162 children. of the children enrolled,5.2% suffered from nightblindness,8.0% had bitot spots,and 2.5% had other vitamin a deficiency sequellae. fifty-three percent of the ict tests showed the presence of vitamin a deficiency. the biochemical mrdr test showed that the vitamin a status of 30% of the study children was critical. twenty-seven of them had retinol levels of <10 μg/dl [mean±standard deviation (sd) 7.02±2.0 μg/dl],and 50% had retinol levels of 10-20 μg/dl (mean±sd 14.2±2.83 μg/dl). the poor health status and low rates of consumption of vitamin a-rich food are the main factors determining critical status. vitamin a deficiency,reflecting poor nutrition and health,is a serious public-health issue among children aged less than six years in congo. © international centre for diarrhoeal disease research,bangladesh.