To assess the impact on prevalence estimates of zinc, iron and vitamin A deficiencies by different recently proposed approaches to correct for inflammation
Iron deficiency was defined as plasma ferritin concentration <12 µg/L and/or soluble transferrin receptor concentration > 8.3mg; zinc deficiency as plasma zinc less than 65 and 57 µg/dl (collection morning and afternoon, respectively) and Vitamin A deficiency as retinol binding protein levels >0.75 µmol/l. Inflammation was defined as C-reactive protein >5mg/l and alpha 1 acid glycoprotein >1g/l. Five approaches were compared in n=461 preschool children aged between 2-6 years from rural Western Kenya:(a) ignoring inflammation, (b) exclusion of inflamed individuals (c) change of nutrient biomarker cut off values for those with and without elevated APP, (d) four level inflammation correction factors and (e) regression modelling
Prevalence estimates varied for all nutrient biomarkers depending on approach used to correct for inflammation: percent decrease range for zinc and vitamin A deficiency was 2%-10% and 43-78% respectively. Iron deficiency prevalence increased by range 0.6-3.6% by all other approaches except exclusion where it decreased by 10%.
Zinc, iron and vitamin A deficiencies as well as inflammation were high in the Kenyan preschool children assessed. Regardless of the approach used to correct for inflammation in this population, there was no substantial difference in Fe and Zn deficiency prevalence estimates.