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 Au-gust-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 question-naire 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 im-pression 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.