Malnutrition and diarrhea. A longitudinal study among urban Mexican children.

To address the hypothesis that malnutrition is associated with an increased risk of diarrhea, the authors identified a cohort of 284 Mexican children less than two years of age in order to equally represent different degrees of nutritional status. Nutritional status, defined anthropometrically, was measured at baseline and every three months for a total follow-up period of one year. The occurrence of diarrhea was assessed by weekly home visits. Among the combinations of weight and length examined, weight for age was the strongest predictor of subsequent diarrhea during a three-month interval. Among normally nourished children, the incidence of diarrhea was 3.3 episodes per year; among those mildly malnourished, 3.7 episodes per year (relative risk (RR) = 1.1); and among the moderately malnourished, 6.0 episodes per year (RR = 1.8). Adjustment for demographic, seasonal, and socioeconomic variables only slightly reduced this association. Nutritional status was most strongly related to the occurrence of two or more episodes during a three-month follow-up interval, and this effect was most clearly seen among children with diarrhea in the preceding interval. In a multiple logistic analysis that included potentially confounding variables as well as an autoregressive term to account for the nonindependence of repeated observations, the relative risk of two or more episodes of diarrhea during an interval was 1.8 (95% confidence interval 1.1-2.9) for moderately malnourished children compared with those who were normally nourished or mildly malnourished. These data lend support to the hypothesis that malnutrition predisposes to the occurrence of diarrhea among young children.